ALBERT

Description: 〈h3〉Abstract〈/h3〉 〈p〉An assessment of the influence and significance of different topographic and morphometric parameters of glacier catchments such as size, average slope, median elevation, and aspect upon the spatio-temporally changing characteristics of glaciers belonging to different size classes in Tista river basin of Sikkim Himalaya has been performed. The reference years of 2000 and 2018 were considered and different morphometric techniques showed recessive nature and shape change of the observed main glaciers along with some of the tributary glaciers. Pearson’s correlation coefficient and Student’s 〈em〉t〈/em〉 test were applied to measure the correlation and statistical significance of used parameters to understand the varying morphometric and topographic conditions of the glaciers. LANDSAT TM (thematic mapper), LANDSAT 7 ETM + (enhanced thematic mapper), and LANDSAT 8 (OLI) (operational land imager) imageries and shuttle radar topographic mission (SRTM) digital elevation model (DEM) and different automated and semi-automated techniques indicated overall loss of 19.78% over the years 2000 to 2018 of the glaciated area investigated and such decrease in respective years of reference was 2.06% for the year 2000 and 1.65% for the year 2018, respectively, of the total geographic area of Sikkim. TanDem-X DEM (90 m) was useful in inferring glacier surface elevation change.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉One of the most crucial design steps to guarantee the long life and the sustainability of artificial recharge of groundwater projects is to find the best locations. The present study focuses on identifying potential zones of groundwater artificial recharge in Shabestar region, northwest of Iran. For this purpose, random forest (RF) model, a learning method based on ensemble decision trees, was proposed for locating groundwater artificial recharge. Important factors, including slope and slope aspect, soil texture, erosion, land use, groundwater quality, permeability and geological lithology were integrated in a geographic information science (GIS). According to RF model, permeability and unsaturated zone thickness were identified as the most effective parameters for locating groundwater artificial recharge sites. Based on the proposed model, it was found that 14% of the region is located in suitable site for groundwater artificial recharge projects. The accuracy of the model was evaluated with receiver-operating characteristic (ROC) curve and the mean squared error (MSE). Low MSE and ROC curve of the model with the highest area under curve equal to 0.947, indicated high accuracy of random forest in locating groundwater artificial recharge.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Loktak Lake is the largest natural freshwater lake of Northeastern India, characteristic by floating islands, known as 〈em〉Phumdis〈/em〉. The lake supports rich biodiversity including some globally threatened species, hence declared as a Ramsar Site. The lake facilitates hydropower, irrigation and provides a livelihood to the local villagers in the form of fishing and agriculture. Loktak Lake is deteriorating in recent years due to rapid urbanization, increased settlement and other anthropogenic activities. A study was, therefore, undertaken to assess the water quality and its trends for this important lake. The water quality of Loktak Lake was assessed in monthly intervals for a period of 3 years, using multiple water quality indices. Temporal distribution functions of the individual water quality parameters and indices were developed to assess the water quality trend of the lake. Overall water quality of this lake was found to be good throughout the year with slight deterioration during winter. However, the water of this lake was a little turbid and contained significant organic load.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this study, the effect of sulfation due to air pollution in the portals of the Ince Minareli Madrasa built of pyroclastic rocks and the Karatay Madrasas (Konya, Turkey) built of marble was investigated. Since the sulfur element in sulfate salts is represented as sulfate, the sulfur contour maps (SCM), obtained by transferring the portable X-ray fluorescence measurements onto the orthophotographs, also show the sulfated crust formation, distribution and anomaly regions on the portal surfaces. Additionally, the anomaly regions originating from the difference in thermal conduction between the sulfated crusts and portal surfaces on thermal camera images were determined, and they were observed to be compatible with the anomaly regions on SCM. However, the size of this correlation depends on the chemistry of the building stone and the thickness of the sulfated crusts. Then, it was determined that the anomaly regions on SCM were distributed in relation to the washing out of sulfated crusts by rainfall and capillary moisture content. Accordingly, portal surfaces were divided into three as the sheltered, washing and capillary regions. Consequently, it was demonstrated that the sulfation effect due to air pollution on historical building surfaces which have appropriate rock chemistry can be determined by non-destructive testing methods like using the SCM supported by infrared thermography. The fact that the method is simple and repeatable and is easily applicable to other buildings was considered as the most important success of the method.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Previous basalt carbonation studies under hydrothermal-like conditions suggested high amount of calcite formation in a shorter period which is related to the andesine dissolution. However, CO〈sub〉2〈/sub〉 capture-induced structural changes in neo-formed minerals have not been studied in detail. To understand these changes, Rietveld refinement and crystallographic characterization were performed for andesine and calcite residue obtained after basalt–water–CO〈sub〉2〈/sub〉 interaction experiments. These results indicate large spontaneous strain within calcite which led to contraction along the 〈em〉c〈/em〉-axis and expansion along 〈em〉a〈/em〉-axis. Thus, contraction/expansion along the 〈em〉c〈/em〉-axes is inversely proportional to 〈em〉a〈/em〉-axis of the calcite and andesine, respectively. Interatomic Ca–O and C–O bond lengths show changes with the experimental run time, signifying mutually inverse relationship. Observed crystal structure distortion is due to variation in the O–M–O bond angle. Ionic bond length between Ca and O atoms decreased after 70 h of experiment run that enabled Ca–O ligand to enter in the phyllosilicates. The Ca–O bond length weakening along 〈em〉c〈/em〉-axis caused shrinkage of calcite crystals. Increased bond length together with the weakened covalent bond between C and O atoms led to calcite degeneration after 80 h of experiments; therefore, no calcite persisted in the system. Thus, basalt carbonation is time-dependent process, where, 〈em〉p〈/em〉CO〈sub〉2〈/sub〉 plays sub-ordinate role, but, at a constant temperature.〈/p〉

Description: 〈p〉The authors would like to correct errors in the original publication as detailed below.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The application of salt–bentonite (Salt–Bent) grouting for the design and construction of grout curtain to form vertical barriers (VB) to serve as seepage remediation measures has been investigated. Recent experiences on the high cost of grout injection materials when conducting a grouting campaign have necessitated the authors to consider the use of clay of the montmorillonite (Mt) type (Wyoming bentonite), which is less expensive; readily available naturally occurring; yet very effective and environmentally friendly grouting material for the construction of grout curtain. Grout curtain is formed by injecting grout slurry into a series of boreholes, drilled through the weathered zone of the subsurface, to form VB. Vertical barriers play a significant role in geo-environmental engineering for the control of horizontal groundwater flow and contaminant spread into the unsaturated–saturated zone of the subsurface. The design and construction of effective grout curtain is key to the overall performance of the barrier and this is dependent on the accurate determination of a design parameter, the critical hydraulic gradient (CHG). A laboratory investigation of the CHG was conducted through grout injection into fractures of aperture sizes 100–60 µm and river sand compacted to different porosities (0.33 ≤ 〈em〉n〈/em〉 ≤ 0.40), to determine the safety thickness of a bentonite-grout curtain to withstand a given hydraulic gradient without failure. The study finds that, the CHG due to the fractured and porous media ranges between 30 and 35; and 180 and 200, respectively. The resulting permeability values obtained from the grouted samples were in the order of 10〈sup〉−7〈/sup〉cm/s or less. It can be inferred from the results that, bentonite-grouting can provide the required permeability for an effective barrier. The results also suggest that, accurate determination of the safety thickness of the barrier is of great importance for sustainable barrier system.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The transport and fate of hexavalent chromium Cr(VI) in slag–soil system, which remain poorly understood, are of great importance for environmental risk assessment and pollution control of Cr(VI) in soil and groundwater. Based on the migration behavior of Cr(VI) in the chromium-containing slag under the effects of rainfall, the transport and fate of Cr(VI) in soil were investigated. Batch and column experiments were undertaken to clarify the Cr(VI) adsorption and transport behavior of aqueous Cr(VI) in soil, respectively. Findings from a combination of experimental and model results clearly suggest that the adsorption of Cr(VI) onto soil is a spontaneous chemical adsorption process. For chromium-soil transport system, the constructed HYDRUS-1D dynamics model is a good simulation for Cr(VI) migration in soil, as the modeling yielded adequate fit for simulated and measured values of Cr(VI) concentration in soil (correlation coefficient 〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.99). The transport modeling then was utilized to assess the transport of Cr(VI) in slag–soil system. Up to the year of 2018, the concentration levels of Cr(VI) in the soil-leaching solution attained 905 mg/L. Due to the thin layer of soil and the high mobility of Cr(VI) in soil, it is no doubt that the Cr(VI) leaching will engender serious pollution of soil and groundwater in the presence of precipitation. The applications and limitations of the HYDRUS-1D were also discussed, such as bacteria transport, more elaborate biogeochemical processes, coupling of vadose zone processes with existing larger scale groundwater flow models.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Influenced by the uncertainties and differences of the variations of precipitation abundance, the water source area of a water transfer project is different from the water receiving area, which will lead to risks for the operation of the water transfer project. In this article, expressions for the exceedance probabilities of wet vs. dry conditions were constructed on the basis of the copula joint distribution function. The flood season, non-flood season, and annual precipitation data from the Jvxian and Rizhao stations of the Shuhe to Futuan Water Transfer Project (SFWTP) were used for the analysis of synchronous and asynchronous exceedance probabilities. The computed results demonstrate that synchronous exceedance probabilities were greater than asynchronous exceedance probabilities via the analysis of the flood season, non-flood season, and annual precipitation, and the favorable probability is largest during the flood season. In order to maximize the SFWTP benefit, it is essential to increase urban water supply in the non-flood season, and transport water in the flood season to Rizhao reservoir. To further analyze the impacts of climate change on exceedance probability, the precipitation data were divided into two sub-periods by Pettitt test. In last sub-period, favorable probabilities increased with the decrease of synchronous exceedance probability in all timescales, which suggests that there are positive impacts of climate change on the exceedance probabilities.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉To investigate the effects of flow rate variation on solute transport in a karst conduit, three pipe structures of a constant diameter pipe, the pipe connected to a symmetrical pool and an asymmetrical pool respectively were chosen, and several tracer experiments were conducted separately in each of the three pipe structures at nine flow rates. Experimental results show that the peak of the breakthrough curve (BTC) increased and the tailing decreased with increasing discharge. Three models, the advection–dispersion equation (ADE), the two-region nonequilibrium model (TRNM) and the transient storage model (TSM), were used to simulate BTCs and explore the change of transport parameters with increasing flow rate. Simulations show that ADE was capable of replicating the almost symmetrical BTCs of the single pipe but incapable of fitting the appreciable BTC tails for the pools. Nevertheless, TRNM and TSM can reproduce all BTCs of single pipe and pipe with a pool very well. The research demonstrates the significant effect of the pool on solute transport. The parameters in the two models (TRNM and TSM) exhibited similar trends with increasing discharge in either pool. In the TRNM, a clear positive correlation with discharge emerged for the partition coefficient and mass transfer coefficient. Meanwhile, the main channel cross-sectional area and exchange coefficient in TSM increased gradually with discharge. The storage zone area decreased generally with increasing flow rate. The relationship between solute transport and the flow rate is more complex in the asymmetrical pool than in the symmetrical pool.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The optimal operation of an interbasin water transfer multireservoir system (IWTMS) is more complicated than a general one-basin multireservoir system because water release and water transfer occur simultaneously. Previous studies primarily employed reservoir zoning and rule curves to deal with the relationship between reservoir water release and water transfer, and the operating priorities for water release and water transfer are established by decision-makers. However, these priorities may be somewhat subjective and result in suboptimal operation of the entire system. To overcome this shortcoming, a genetic algorithm (GA)-based optimization model was developed to endeavor to get the optimal operation of an IWTMS. The optimization model consists of a GA and a simulation process based on water balance equation, and was applied to a typical IWTMS in Rizhao City, Shandong Province, China. The results showed that the GA was effective and efficient on solving the optimization problem of IWTMSs, and the reliability of the system’s water supply increased from 70.6 to 88.4% due to water transfer and could increase further to 96.4% by implementing optimization.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Humans are daily exposed to the natural radioactivity present in rocks, soils, and water. The distribution of these elements in the surface is not uniform, being influenced by the variation of the physical, geological, and meteorological parameters. The concentration activities of natural radionuclides 〈sup〉238〈/sup〉U, 〈sup〉226〈/sup〉Ra, 〈sup〉228〈/sup〉Ra, and 〈sup〉222〈/sup〉Rn were determined in the groundwater supplying the Salutaris Mineral Waters Park, in Paraíba do Sul, in the state of Rio de Janeiro. The concentrations of 〈sup〉238〈/sup〉U varied from 0.95 to 2.70 μg L〈sup〉−1〈/sup〉 with a mean concentration of 1.96 μg L〈sup〉−1〈/sup〉, 〈sup〉226〈/sup〉Ra ranged from 1.50 to 12.6 mBq L〈sup〉−1〈/sup〉 with an average of 5.03 mBq L〈sup〉−1〈/sup〉, 〈sup〉228〈/sup〉Ra presented levels between 1.80 and 2.80 mBq L〈sup〉−1〈/sup〉, with an average of 2.40 mBq L〈sup〉−1〈/sup〉, and 〈sup〉222〈/sup〉Rn, with levels of 5.90–1.94 × 10〈sup〉4〈/sup〉 mBq L〈sup〉−1〈/sup〉 with an average concentration of 7.50 Bq L〈sup〉−1〈/sup〉. The contribution of the consumption of these radionuclides dissolved in the water distributed in the Park to the effective annual dose ranged from 0.03 to 0.10 mSv year〈sup〉−1〈/sup〉, with an average of 0.08 mSv year〈sup〉−1〈/sup〉. The results showed that all effective annual dose values per ingestion of these mineral waters were below the individual dose limit of 0.10 mSv year〈sup〉−1〈/sup〉 recommended by the World Health Organization (WHO).〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉An attempt to understand the structural and sedimentation framework in the Benin Basin is made herein. Unlike in its contiguous basins in the Gulf of Guinea Province, no significant oil and gas discovery has been reported in the basin. The aim here is to provide a chronostratigraphic framework of sediments build-up as a guide to hydrocarbon prospectivity in the basin. Existing biostratigraphic and sedimentologic data as well as few proprietary reports were integrated to establish a chronostratigraphic correlation in six directions within the Nigerian portion of the Benin Basin. Isopach maps of the chronostratigraphic subdivision of the sequences in the basin were also made. Sedimentation in restricted grabens started in the western part of the basin. Only Ise-2 well penetrated the oldest Cretaceous (Neocomian to Albian) sediments in the area of study with a thickness reaching up to 869 m. During the Miocene the focus of sedimentation predominantly shifted towards the offshore in the basin. Significantly a missing Eocene/Oligocene section was observed both on the seismic section and the stratigraphic record of the basin. Only Epiya-1 shows gas occurrence in the Miocene. Based on this work and locations of hydrocarbons recovery in the other part of the basin, exploration effort should target the Cretaceous sediments in the Nigerian portion of the basin.〈/p〉

Description: 〈p〉Unfortunately the online version of the original article contains several citations of Jannis et al. 2018, where the first and last name was accidently mix up.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Floodwater resource utilization, a new term or concept was proposed in the early 21st century in China, and has been practiced over the past 20 years in order to adapt to the uncertain effects of climate change on regional droughts and water scarcity. The applications shown that the effect was good and necessary to alleviate the regional water shortage. This special thematic issue collected 14 articles covering three continents—Asia, America and Europe in term of research area, which come down to basic concepts, evaluation methods, utilization models and usable patterns and so on. Through this thematic issue, the lessons, experiences, and achievements on floodwater resources utilization achieved mainly in China can be shared with world audiences, especially to regions affected by the monsoon climate, with similar hydrologic characteristics and water resource needs as in China.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The microcrack propagation-coalescence mechanism and stress–strain constitutive model of brittle rock is of great significance for prediction of mechanical properties. To establish a more applicable constitutive model of brittle rock, the crack model based on fracture mechanics was introduced. First, based on the crack slip model and maximum circumferential stress theory, a theoretical equation for crack propagation length was established. The microcrack propagation-coalescence mechanism of brittle rock material under loading was studied. On this basis, a macro-coalescence zone model was proposed. Through the relationship between the deformation characteristics of stress–strain curves at different crack growth stages and the behavior of microcracks, a complete stress–strain constitutive model of brittle rock based on the crack model was theoretically deduced. The constitutive model was verified by the results of a coupling hydro-mechanical test of granite carried out after different heat treatment temperatures. The advanced intelligent algorithm, genetic algorithm, was adopted to simulate experimental data. The research results showed that: (1) The derived stress–strain constitutive model of brittle rock is not only high in accuracy of stress–strain simulation, but also can simulate both the axial and circumferential stress–strain curves. Moreover, the dilatancy and crack initiation stresses can be obtained directly. (2) The parameters of the stress–strain constitutive model not only have clear physical meaning, but the mechanisms of rock mechanical properties, such as dilatancy, acoustic emission, and stress fluctuation, can be explained.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The GlobalTreeSearch database provides the names of all tree species known to science and the countries where these trees grow. TreeeX is a visual exploration system that supports multifaceted analyses of the GlobalTreeSearch data. Investigating research questions on biodiversity and conservation on a global or national scale are visually supported by interactive choropleth maps that color countries according to frequency, diversity or uniqueness of prevalent tree species. By combining the GlobalTreeSearch and ThreatSearch data sets, additional information on the conservation status of trees can be visualized globally and nationally through TreeeX. Similarities and differences in tree diversity, endemism and conservation status to other countries can be analyzed in detail. Several examples outline the system’s capability of delivering insights concerning the geographical diversity of tree species. 〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Numerous groynes had been constructed on the Dwarkeswar River to improve bank protection. Among them, groynes adjacent to the village Rautara of Khandaghosh Block, West Bengal have been studied which were constructed in the year of 2009. This study investigates the alteration of channel morphology, sedimentology and flow characteristics influenced by emerged groynes through micro-level field study. An extensive field survey has been made with a dumpy level and fifty-nine sediment samples were collected from the field. Different channel parameters such as degradation aggradation ratio, braided index, channel instability and bar occupied area indices have been used from 2003 to 2018. The simulation of channel flow has been done using HEC RAS. It has been found that width/depth (w/d) ratio, bankfull channel width, channel area and sand-bed length of the river decrease due to groyne construction. On the other hand, channel maximum bankfull channel depth, depositional rate, the difference between average depth, maximum depth and braided index drastically increased. Increasing flow velocity, flow deflection with coarse and poorly sorted multimodal sediments near the tip of the groynes as well as decreasing flow velocity, curve flow path, accelerated sedimentation with elevating river bed have been observed. Altogether result indicates that the emerged groynes are effective in protecting the river banks at the cost of channel degradation.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Gatifloxacin (GAT), a new generation fluoroquinolone antibiotic, is widely used in the world but its environmental behavior has been rarely studied. In this study, the adsorption and desorption characteristics of GAT interacting with goethite and hematite at pH 6.0 ± 0.1 were investigated by batch experiments combining with attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The results indicated that the total desorption ratio of GAT from goethite (70.8–84.8%) after three desorption steps was far higher than that from hematite (7.8–39.4%). In GAT adsorption onto goethite and hematite, a strong dependence on ionic strength was only observed for goethite. These all suggested that outer-sphere complexation was the main mechanism of GAT adsorption onto goethite while inner-sphere complexation dominated the adsorption onto hematite. No evidence for inner-sphere coordination was found at the goethite surface in this study under our conditions. Due to the difference in adsorption mechanisms, the pH at point of zero charge (pH〈sub〉pzc〈/sub〉) of hematite increased by about 1.0 unit after adsorption in relation to the pristine hematite, but the increase of goethite pH〈sub〉pzc〈/sub〉 was less than 0.3 unit. ATR-FTIR observations indicated that the surface hydration-shared ion pairs involving in strong hydrogen-bond interactions were predominant in GAT adsorption onto goethite. However, a bridging bidentate surface complex with hematite was most likely formed. Our results are helpful to advance understanding of the importance of comparatively strong ionic hydrogen-bonding interactions for adsorption processes of fluoroquinolones at the goethite/water interface. The findings of this study suggest that soils with goethite as the main mineral compositions may have very limited retention ability for GAT under field conditions.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Intensive use of fertilizers in the agricultural lands and a swift-flying of coal and allied industries in Korba district, India in an unprecedented manner has led to groundwater contamination. Accordingly, an integrated modified DRASTIC and risk index model combined with other statistical techniques are applied to evaluate groundwater susceptibility and pollution risk in the region. The ArcGIS based spatial distribution map of the DRASTIC vulnerability index (DVI) reveals that the high (63%) and very high (23.61%) vulnerable zones identified in DVI map are reduced to that of 57.86% and 17.74%, respectively, when compared with pollution risk map. Results of sensitivity analysis, i.e., map removal sensitivity analysis and single parameter sensitivity analysis confirms that amongst seven DRASTIC parameters the net recharge parameter is the most influencing parameter in view of the groundwater contamination. The linear correlation coefficient (〈em〉r〈/em〉 = 0.89) obtained between risk index values and NO〈sub〉3〈/sub〉 concentrations alongside nearly 75% of the study area comprises of agricultural lands and forest/tree clad area corresponds to high to very high risk contamination zones reveal the model validation in the light of the influence of anthropogenic contamination factor in these zones. Furthermore, elevated iron concentration also supports the certain influence of geogenic contamination within the study area. In essence, this study can be effectively utilized in the planning and management of precious groundwater resources in high to very high vulnerable and risk zones of the study area, for its overall sustainable development.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Radium isotopes, 〈sup〉223〈/sup〉Ra and 〈sup〉224〈/sup〉Ra, and salinity measurements were used to assess submarine groundwater discharge from a karstic aquifer system into a coastal lagoon located at Oualidia (Morocco), on the Atlantic shoreline. The Oualidia lagoon is classified as a Ramsar area owing to its ecological significance. Groundwater discharge to the lagoon occurs as intertidal springs, submarine springs and probably diffuse leakage. Groundwater sources and discharge fluxes were determined using mass balance calculations following single and multi-box approaches. Calculated flow rates varied from 0.2 ± 0.2 to 1.2 ± 0.6 m〈sup〉3〈/sup〉 s〈sup〉−1〈/sup〉. The single-box model can be considered representative enough of water cycling and mixing within the Oualidia lagoon. However, a certain complexity of the hydrological processes should be taken into account as the discharge varies from low to high tide periods. The discharge amount suggests that the Oualidia lagoon may contribute significantly to the regional karstic discharge. Both the regional geological structure and the piezometric map indicate a convergence of groundwater to the area of the lagoon which is located in the bottom of a large geological depression. It is deduced that a close relationship exists between the karst development and the lagoon.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Sarchinar, Bestansur, and Tabin springs are large springs in Sulaymaniyah Governorate, Iraqi Kurdistan Region, which are considered for use as public supply. To evaluate the hydrochemical properties and heavy metals content of the selected springs, 80 water samples were collected continuously beginning on 24th Oct. 2015 through 24th July 2016. The results show that the water is odorless, colorless, contains a low value of total dissolved salts, predominant ions are calcium and bicarbonate, and all the water samples are not polluted with Cd〈sup〉2+〈/sup〉, Pb〈sup〉2+〈/sup〉, Cu〈sup〉2+〈/sup〉, Ni〈sup〉2+〈/sup〉 ions. The vulnerability of the selected springs is assessed using EPIK (epikarst, protective cover, infiltration condition, and karst network development) method. Vulnerability maps are counted as starting a new step for a better determination of springs’ water protection areas especially in the karst environment as the maps are generated based on different attributes as specified by adopted methods. Delineating springs’ protection zones are proposed depending on vulnerability assessment and recession curve analysis. Based on the EPIK vulnerability map, protection zones for all selected springs are defined using the equivalent relationship between the groundwater protection areas S and the protection factor 〈em〉F〈/em〉〈sub〉p〈/sub〉. Therefore, three protection areas for selected springs are recognized and based on recession curve analysis; two vulnerability scenarios are defined with an assessment of the proper dimensions of the protection zones for selected springs. The delineated protection zones around the tapped springs consist of three zones (immediate, inner, and outer protection zones).〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The availability of safe drinking water is imperative for healthy life but access to safe drinking water has become a major problem around the world, especially in developing countries such as Pakistan. The present study aimed to: assess the suitability of groundwater for potable use in Gujranwala district, Pakistan; examine the spatial distribution patterns of water quality parameters; and to identify the prevalence of waterborne diseases among locals and health risks to humans due to the consumption of groundwater. Eighty drinking water samples were collected from different areas of Gujranwala and analyzed following Standard American Public Health Association methods. A questionnaire survey related to the incidence of waterborne diseases in the area was also carried out. The averaged water quality index (AWQI) was computed using ArcGIS 10.3 model builder. The AWQI map indicated that the water quality was generally suitable for potable use with regard to its physiochemical parameters. However, 97.5% water samples were found to be bacteriologically contaminated. The mean concentration of metals in drinking water showed a decreasing trend in the order Cr 〉 Cu 〉 Zn 〉 As 〉 Co 〉 Ni 〉 Cd. Health risk index (HRI) was also calculated for exposure to metal concentration. For Cd, one sample showed an HRI value 〉 1 i.e. 1.59 and 1.36 for child and adult, respectively, while HRI for As showed values 〉 1 varying between 0.5 and 11 for child, and 0.4 and 9.6 for adults. For other metals HRIs was less than 1 (considered to be safe for the consumers). The study concludes that groundwater quality of study areas of Gujranwala has mostly deteriorated.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Groundwater quality assessment is important for potability and for industrial and agricultural uses of water. Groundwater quality is a measure of contamination by chemicals, biological organisms, sediments, and heat. Reductions of groundwater quality in some areas due to high rates of consumption have prompted the identification of regions in which extraction will be focused. In this study, geographic information systems (GIS)-based analytical network process (ANP) and analytical hierarchical process (AHP) multiple-criteria decision-making techniques using a fuzzy-quantifier algorithm were devised to model groundwater quality in northern Fars Province, Iran. Groundwater quality was assessed by measuring calcium (Ca), chlorine (Cl), magnesium (Mg), thorium (Th), sodium (Na), sulfate (SO〈sub〉4〈/sub〉), electrical conductivity (EC), and total dissolved solids (TDS). A membership function based on World Health Organization (WHO) groundwater quality standards was used to create a fuzzy map of each parameter in ArcGIS. Fuzzy maps were generated for each layer using a trapezoidal membership function. The AHP and ANP methods provided weights for each layer to generate groundwater quality maps. Using a feature-selection algorithm, the relative importance of the factors that affect groundwater quality was determined. The results show that, according to the AUC values, ANP generates higher accuracy than fuzzy-AHP (0.954 in comparison to 0.845). The feature-selection algorithm indicates that Ca, Cl, EC, and Na had the greatest impact on groundwater quality conditions. Using ANP and selecting the most important factors can be an economical way, in terms of time and money, to produce highly accurate information that can be used to predict local groundwater quality.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The stability of natural and man-made rock slopes has always been of great concern for engineering geology studies. To ensure a safe and functional design of excavated slopes, the first and most crucial step is to use reliable input parameters while searching for possible failure modes at the preliminary design stage. It is highly important for practicing engineers to determine the best material property for a chosen failure criterion. This study aims to analyze the stability condition of a case road cut from different aspects. For this purpose, two well-known failure criteria proposed for rock masses and rock joints were applied in the study depending on the scale of the problem in the slope face. The Hoek–Brown failure criterion was used to obtain input data required for modeling intact rock and rock mass behavior, and the Barton-Bandis shear strength criterion to determine the input data necessary for the modeling of rock joint behavior. 〈em〉SMRTool〈/em〉 and 〈em〉Dips 7.0〈/em〉 programs were utilized to analyze the structurally controlled instabilities due to discontinuities in the cut slope. 〈em〉Slide 2018〈/em〉 and 〈em〉RS2 9.0〈/em〉 programs were executed to examine the stability condition of cut slope subjected to circular and non-circular failures, respectively. According to the results of numerical and limit equilibrium methods, no stability problem occurred in the case of slope due to non-sliding circular or non-circular slip failures. However, according to the results of empirical and kinematical analyses, some structurally controlled sliding failure modes of planar, wedge, and toppling were expected on the slope face. The result of this study clearly shows that to reach a final decision, different analysis methods should be used to evaluate the stability of cut slopes by considering various conditions of jointed rock masses.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Riverine organic carbon export plays a major role in the global carbon cycle. The biodegradability of riverine dissolved organic carbon (DOC) determines both greenhouse gas emissions and the amount of refractory DOC. However, seasonal changes in organic carbon and factors controlling DOC biodegradation are still not well understood in large rivers. Here, we examined the monthly changes in concentrations of particulate organic carbon (POC) and DOC in a large subtropical river (Changjiang River, Nantong Section, China) in 2017. We also measured biodegradable DOC (BDOC), specific UV absorbance (SUVA〈sub〉254〈/sub〉), neutral sugar concentrations and their compositions. The results showed that POC had no significant relationship with water temperature, precipitation, and discharge. DOC concentrations were significantly negatively correlated with all these parameters, and water temperature explained 61% of the variance in DOC. BDOC concentrations varied between 0 and 14.01 ± 1.22 mg C/L and were closely associated with DOC (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.85, 〈em〉p〈/em〉 〈 0.001). The negative correlation between BDOC% and SUVA〈sub〉254〈/sub〉 (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.63, 〈em〉p〈/em〉 〈 0.01) suggested that high aromaticity was associated with low bioavailability. Water temperature was positively correlated with total neutral sugar yield (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.43, 〈em〉p〈/em〉 〈 0.001), which was mainly composed of glucose and deoxysugars in the warm season; thus, neutral sugar composition is a useful indicator of DOC decomposition. Taken together, our study showed that POC has no clear seasonal change, while DOC exhibits a strong seasonal change, and high water temperature leads to low BDOC in a large subtropical river.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Soft computing methods are increasingly being used as substitutes for traditional statistical analysis tools to predict uniaxial compressive strength (UCS) and elastic modulus (〈em〉E〈/em〉). In this paper, multiple regression (MR) analysis and fuzzy inference system (FIS) were used to estimate UCS and 〈em〉E〈/em〉 of migmatites in the Sanandaj–Sirjan zone in Iran. A series of rock index properties including porosity (〈em〉n〈/em〉), cylinderical punch index (CPI), block punch index (BPI), Brazilian tensile strength (BTS), point load index (IS〈sub〉(50)〈/sub〉), and P-wave velocity (〈em〉V〈/em〉〈sub〉P〈/sub〉) were measured and employed to develop six prediction models. Amongst the rock indices, IS〈sub〉(50)〈/sub〉 and 〈em〉V〈/em〉〈sub〉p〈/sub〉 had the best correlations with UCS and 〈em〉E〈/em〉, respectively. Performance evaluation indicated that FIS is a more reliable tool for predicting UCS and 〈em〉E〈/em〉 of migmatites, due to its ability in managing uncertainties in the test results with clarity and precision. The results indicated that FIS model 2 which employs 〈em〉n〈/em〉, CPI, BTS, and 〈em〉V〈/em〉〈sub〉P〈/sub〉 as input variables and FIS model 3 which employs 〈em〉n〈/em〉, CPI, IS〈sub〉(50)〈/sub〉, and 〈em〉V〈/em〉〈sub〉P〈/sub〉, performed better than other models in predicting UCS, while, FIS model 2 also produced the best results for predicting 〈em〉E〈/em〉. The results of performance evaluation demonstrate that the developed models are highly efficient for prediction and the input parameters have notable influence on UCS and 〈em〉E〈/em〉.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉A surface drainage system (SDS) controls catchment hydrology and acts as an indicator of geomorphologic processes. In this study, a field-based and GIS-integrated approach enabling reconstruction of a surface drainage system, which operates during heavy rainfall in small flysch catchments, has been proposed. The reconstruction is based on the ALS-LIDAR data. The reconstruction of the SDS gave the opportunity for analysis of the changes between the river system and the SDS operating during heavy rainfalls. Results have revealed that the SDS operating during heavy rainfalls is several times better developed than the river system. The density has increased from c.a. 1.5 to 13.7 km·km〈sup〉− 2〈/sup〉. Moreover, the structure of the SDS has changed, what was confirmed by the parameters of the Hortonian type of the analyses. The most significant changes were related to the first- and second-order streams. These streams were, the most frequently, the man-origin incisions and natural-origin incisions/concavities on the hillslopes conditioned by micro-relief. The man-origin sub-system reached up to 35% of the SDS functioning during heavy rainfalls, whereas the sub-system composed of incisions/concavities conditioned by micro-relief reached up to 24% of this SDS. Smaller lateral valleys included to the SDS during heavy rainfalls constitute up to 37% of the SDS. The permanent streams constitute the remaining part of the SDS. Changes in the SDS have the influence on the drainage pattern, hydrological response of a catchment, and intensity of geomorphological processes; therefore, the changes in the SDS and their consequences have been discussed.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The Mediterranean mountains of Morocco (“Rif”) show an intense sensitivity to hydro-climatic hazards. Hydrologic achievements are thwarted by a series of constraints that request strategic consolidation. The acceleration of socioeconomic activities is causing an increasing pressure on water resources that are already facing insufficiency and degradation problems. This paper aims at geophysical characterization of the most important intramountainous alluvial aquifer on the Rif, Ghis–Nekor. Its electrical and hydrogeological properties are investigated through a correlation of 2D electrical resistivity tomography (ERT), vertical electrical sounding (VES) and borehole data. The results have shown that this monolayer coastal aquifer is constituted of large coarse sand, gravel and pebble deposits that overlay substrata of different hydrogeological and electrical types. A geoenvironmental survey was also carried out in the coastal zone and near the uncontrolled waste landfill of Beni Bouayach. The 2D ERT profiles indicate an increase of marine water intrusion (over 2 km) particularly on the eastern bank of the Nekor river. They also show a spread of the landfill leachate flow path beyond 1 km in the direction of the groundwater flow (to the North), towards an area of hydrogeological interest located east of the city of Imzouren. These results imply a socioeconomic and environmental vulnerability that evokes an immediate intervention to restore weakened equilibrium.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Water temperature impacts many processes in rivers, and it is determined by various environmental factors. This study proposed an extreme learning machine (ELM)-based model to predict daily water temperature for rivers. Air temperature (〈em〉T〈/em〉〈sub〉a〈/sub〉), discharge (〈em〉Q〈/em〉) and the day of the year (DOY) were used as predictors. Three rivers characterized by different hydrological conditions were investigated to test the modeling performances and the model results were compared with multilayer perceptron neural network (MLPNN) and simple multiple linear regression (MLR) models. Results showed that inclusion of three inputs as predictors (〈em〉T〈/em〉〈sub〉a〈/sub〉, 〈em〉Q〈/em〉 and the DOY) yielded the best modeling accuracy for all the developed models. It was also found that 〈em〉Q〈/em〉 played a minor role and 〈em〉T〈/em〉〈sub〉a〈/sub〉 and DOY are the most important explanatory variables for river water temperature predictions. Additionally, sigmoidal and radial basis activation functions within the ELM model performed the best for river water temperature forecasting. ELM and MLPNN models outperformed MLR model, and ELM model with sigmoidal and radial basis activation functions performed comparably to MLPNN model. Overall, results indicated that the ELM model developed in this study can be effectively used for river water temperature predictions.〈/p〉

Description: 〈p〉In the original publication the title of the article was published wrongly as “Geotechnical aspects and associated problems of Al-Shuaiba Lagoon soil, Red Sea c, Saudi Arabia”.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Chemical stabilization is extensively used to improve the physical and engineering properties of problematic soils. This research was carried out to investigate the strength and microstructural properties of organic soil treated with a biomass silica stabilizer, named SH-85. The SH-85 content studied was varied at 3, 6, 9, 12, and 15% based on the organic soil weight. Compaction and unconfined compression strength tests were carried out to ascertain the strength improvement of the stabilized organic soil. The field-emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectrometry (EDAX) were carried out to examine the growth of cementation products. The cementation products filled large and small pores and welded soil particles, which results in strong interparticle forces. Therefore, the strength of treated soil is 5–20 times higher than that of the untreated soil.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Mercury (Hg) was used during 1929–1950 as a catalyst to produce rayon acetate at the former DuPont plant in Waynesboro, Virginia, and released into the South River. Though the use of Hg ceased in the 1970s, the affected ecosystem is still a matter of concern. Here, high total mercury (THg) and total organomercury, stated as methylmercury (MeHg) are reported in historically contaminated floodplain soils and shallow groundwater from five locations sited 5.6 km downstream from the plant of one river edge site. In soils, THg ranged from 0.1 to 1201.5 mg/kg exceeding the health-based screening Hg levels for residential and industrial soils while MeHg varied between 0.1 and 54 µg/kg. Concentrations decreased sharply with depth indicating the stratification of legacy industrial Hg-rich soils underlain by the pre-industrial soils with minor Hg. Strong linear correlation between THg and MeHg was observed. Highest soil MeHg was associated with total carbon, poorly crystalline and amorphous Fe and/or Mn oxyhydroxides. Sequential extraction analyses indicated that Hg was present mostly in relatively recalcitrant forms, as determined with procedures that targeted β-HgS, HgS, HgSe, HgAu, thiol-bound Hg, Hg〈sup〉0〈/sup〉, and some organo-complexed Hg, Hg〈sub〉2〈/sub〉Cl〈sub〉2〈/sub〉 phases. High Cu (≤ 404.3 mg/kg), Zn (≤ 151.3 mg/kg), Cr (≤ 123.9 mg/kg) were also identified. In shallow groundwater, THg ranged from 28 to 538 ng/L and MeHg varied between 1.2 and 137 ng/L. During the intermittent precipitation, the highest MeHg was linked to the highest Fe〈sup〉2+〈/sup〉, Mn, SO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉, total alkalinity, and conductivity, which could be due to either the potential leaching and dissolution of soil minerals and/or the saturation of the vadose zone. A sharp increase in the soil moisture at the top 40–70 cm of the Hg-rich soils after rainfall and overbank flooding was followed by redox gradients from oxidizing (≈ + 600 mV) to reducing (≈ − 300 mV) and a reverse response in a transmissive gravel zone at the base of the bank (≈ − 400  to + 200 mV) with a defined lag with depth. These dynamic seasonal fluctuations at the South River might be crucial for solubilization of Hg, Fe, and Mn redox-sensitive minerals triggering the anoxic response for new MeHg production.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The method is proposed for assessing water consumption in the transboundary basin under the scarce available data on exploitation of water resources. The method is based on analysis of the dynamic rain–flow relationship which confirms the consistent flow decline during subsequent sub-periods as a result of the increased water consumption. The proposed method was applied to the Yarmouk River Basin up to the Maqaren Station. The study area (6058 km〈sup〉2〈/sup〉) includes Syrian (more 80%) and Jordanian territories. The present study provided complete information on consumption from the Yarmouk River in Syria (1971–2009) and confirmed its significant impact on flow reaching Jordan (downstream area) and on aquifer discharge through springs. During 1997–2009 the total water consumption was estimated as 76% of the Yarmouk Natural Flow vs. 24% for the measured flow at Maqaren Station. Similar estimates for surface water and for groundwater are 82% and 67% vs. 18% and 23%, respectively. In 2006–2009, annual consumption (total, SW and GW) critically increased and reached to 95–100% of the Natural Flow. The perennial base flow of the Yarmouk River at Maqaren Station is caused by outflow of springs in the outlet section of the Hreer tributary, which represents the local aquifer discharge. Its mean annual value was assessed as 120 MCM (40% of the Yarmouk natural flow) but it decreased to almost complete dry-out in 2006–2009 under conditions of the decline in the water level of the basin aquifer and the depletion and drying of the springs as the result of the unrestrained increased pumping of groundwater. These results are useful for water balance estimation as well as for assessment and management of the water resources in Syria and Jordan. The method can be adapted to real-time monitoring of the water consumption from the Yarmouk River (Syria). The proposed method can be applied to other areas with problems of the transboundary water relations under scarce water resources and limited data on the water use.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This study aims to quantify soil organic C density (SOCD) in tropical semiarid mangroves and to compare these results to SOCD under the main tropical semiarid vegetation units (VU), aiming to better understand the role of semiarid mangroves in C sequestration, as well as to provide a basis for a better quantification of human impacts on this ecosystem. SOCD was quantified in two sets of calculations: at a 40-cm soil depth and considering the same soil mass (equivalent SOC). Mangroves can be considered the main organic C sink in the tropical semiarid environment, storing twice as much organic C per area as semiarid VUs, when considering the upper 40-cm soil layer and almost 6 times as much organic C per area when considering the same soil mass. Anthropogenic impacts (disposal of nutrients and vegetation removal) on the studied mangroves decreased SOCD and resulted in a 4.94 ± 0.74 Tg CO〈sub〉2〈/sub〉 emission, equivalent to 5.2% of the Brazilian annual CO〈sub〉2〈/sub〉 emission by fossil fuels. Compared to mangroves from tropical humid regions, SOCD in tropical semiarid mangroves is considerably lower.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Understanding the mechanisms and processes of groundwater recharge and evolution is critical for sustainable water resources management to meet human and agriculture needs under climate change, because groundwater is the primary water source in semiarid and arid regions, where the surface water resources are usually highly unstable and scarce. However, few studies investigated the recharge and evolution processes of groundwater combining with isotopic geochemistry and radiocarbon data, especially focused on the interactions among precipitation, surface water, groundwater, and rock. This study examined the recharge and evolution processes of groundwater in the Wuwei Basin based on stable isotopes, chemical indicators, and radiocarbon data. Our results showed that the Na〈sup〉+〈/sup〉 (sodium ion) and K〈sup〉+〈/sup〉 (potassium ion) concentrations of the groundwater were controlled by the dissolution of sylvite and halite origin from sediments, whereas the increase of Na〈sup〉+〈/sup〉 and Cl〈sup〉−〈/sup〉 (chloride ion) concentrations were not in accordance with a ratio of 1:1, indicating that the Na〈sup〉+〈/sup〉 and K〈sup〉+〈/sup〉 concentrations in groundwater were barely affected by the dissolution of halite and sylvite. Meanwhile, we also found that bicarbonate ion (HCO〈sub〉3〈/sub〉〈sup〉−〈/sup〉) was the dominant ion with a decreased ratio in the groundwater. The SO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉/Cl〈sup〉−〈/sup〉 (sulfate ion/chloride ion) ratio decreased with the sample profile from Southwest to Northeast due mainly to the increases of Cl〈sup〉−〈/sup〉 concentration. The Ca〈sup〉2+〈/sup〉/Cl〈sup〉−〈/sup〉 (calcium ion/chloride ion) ratio decreased with the enhancement of Cl〈sup〉−〈/sup〉 in the hydrodynamic sluggish belt. In addition, the δ〈sup〉18〈/sup〉O (oxygen isotope) and δ〈sup〉2〈/sup〉H (hydrogen isotope) values of groundwater gradually increased from Southwest to Northeast along the flow path. The heavy isotopic values were more strongly depleted than the isotopic values of precipitation in the ground water samples, suggesting that the recharge of ground water in the plain region was very limited from precipitation. Moreover, the groundwater in the phreatic aquifer was younger water with 〈sup〉3〈/sup〉H (tritium isotope) values from 47 to 71 a.BP (before present), while the groundwater age in the confined aquifer was 1000–5800 BP evidenced by the 〈sup〉14〈/sup〉C (carbon isotope) values between 48 and 88 pmc (percentage modern carbon content). Overall, these results suggested that the unconfined groundwater enriched along the overall groundwater flow path from the southwest to northeast of the Wuwei Basin and the melt water from the Qilian Mountains may determine the water isotopic composition and contributed to the steady long-term runoff of the Shiyang River. Our findings may have important implications for inter-basin water allocation programmes and groundwater management in the Wuwei Basin.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Organochlorinated pesticide (OCP) concentrations were evaluated in sediment, soil and surface water of the Msunduzi River as well as the influent, effluent and biosolids from the Darvill wastewater treatment plant (WWTP) of Pietermaritzburg, South Africa. Samples were extracted with dichloromethane using an ultra-sonication method, and cleaned up using multilayered silica gel and analysed using gas chromatography-mass spectrometry. The results showed that all 13 selected OCPs were detected in all the environmental media as well as in the wastewater treatment plant samples. The results revealed that the OCP concentrations along the sites varied based on the anthropogenic activities of the area. The influent of the Darvill WWTP and Du Toit (DUT) site were found to be the most polluted sites. The results from the winter sampling showed highest concentrations of OCPs compared to the spring season. Sediment was found to contain significant amounts of all the selected OCPs with water samples containing the lowest concentrations for both winter and spring seasons. Among the OCPs evaluated, dichlorodiphenyltrichloroethane (DDT) and its metabolites were predominant in all.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The work presented in this article is a part of the international European Commission FORGE project which studied the behaviour of repository gases in the context of radioactive waste disposal. Experimental work is essential to understand the main transport mechanisms for gas and to determine the main geophysical parameters. However, while laboratory and rock experiments can help to investigate the short- and partly the middle-term behaviour of gas in a rock formation, long-term predictions have to be based on numerical simulations. Numerical simulation of long-term gas behaviour in a deep geological repository was one of the aims in the FORGE project. The objectives of the FORGE modelling were to describe the state-of-the-art consideration of gas in performance assessment, and to propose an updated treatment of gas issues in long-term safety assessments for high-level radioactive waste and spent nuclear fuel. Three benchmark exercises for a hypothetical geological repository in clay host rock ranging in scale from a single disposal cell to the whole repository were defined. To provide added value to this benchmark, a feature not yet well represented in typical gas simulations was introduced: the explicit representation of the interfaces between the excavation disturbed zone and the engineered elements within the excavation, such as waste canisters, bentonite plugs, and access drifts. In order to assess gas transport behaviour at the whole repository scale, models were developed with ‘mathematical’ or ‘numerical’ upscaling techniques for small-scale features. The assessment across different modelling scales revealed the main long-term gas migration pathways and led to the conclusion that the explicit representation of interfaces is not important.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Obtaining groundwater of a suitable quality for irrigating crops can be difficult in semi-arid regions in low-income countries like Iran, particularly under conditions where annual rainfall may be declining due to the effects of climate change. Due to substantial difference in the melon production of two important groundwater basins in the Jim-Abad and Torbate-Jam areas in northeastern Iran, groundwater was sampled from 23 wells from these basins and chemically analyzed for physicochemical parameters appropriate for irrigation. These data were used to determine sodium adsorption ratio (SAR), salinity hazard (SH) and irrigation water quality index (IWQI) values and were subjected to statistical assessment to determine the key factors that influence the chemical composition of groundwater in the area. The results of the IWQI survey indicated that 67% of groundwater samples from the Jim-Abad plain and all but one of the samples from the Torbate-Jam plain had a severe limitation for irrigation use. A Piper plot indicated that groundwater quality in the two basins was dominated by sodium and chloride ions. A Gibbs plot suggests that evaporation is the dominant control on groundwater quality in the two basins, although there appears to a significant influence of water–rock reactions in the Torbate-Jam basin. An assessment of the data using cluster analysis and principal component analysis suggests that carbonate dissolution under the influence of the common ion effect also has a significant effect on the quality of groundwater in the region.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The positions distribution of the regional variables in space have irregular or sometimes random scatter. In such a case, their study can be rather difficult and sometimes impossible by means of differential equations. Although variogram or semi-variogram (SV) methodology in the literature is employed to model the regional variable, in this paper, the use of the point cumulative SV (PCSV) procedure application is suggested for the 〈sup〉137〈/sup〉Cs data, which is one of the most important radioactive nuclei not only for radioactive contamination of the environment after the Fukushima Dai-Ichi Nuclear Power Plant, but any nuclear accident whatsoever. As a result of the PCSV models, the categorical description of the 〈sup〉137〈/sup〉Cs concentrations spatial distribution and transport characteristics are determined and interpreted. Prior to the application of the model, log-transformation is performed to fit the 〈sup〉137〈/sup〉Cs data to the classical normal probability distribution and the normality of data is tested by Kolmogorov–Smirnov test. According to the PCSV models, five different categories describe whole spatial distribution and transport properties of 〈sup〉137〈/sup〉Cs concentrations and also iso-radioactivity map is obtained for 〈sup〉137〈/sup〉Cs.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The studied area is part of the sandy plain of the South of Córdoba (Argentina). The objective of this work was to better understand the controls on groundwater geochemistry in the unconfined aquifer, especially in relation to arsenic occurrence and mobilization in groundwater, to provide baseline information for water managers. The aquifer shows a varied spatial geochemical pattern with fresh-to-salty water (0.4–10.0 g/L) and sodium bicarbonate-to-sodium chloride geochemical types, in some places of mixed anionic type. The groundwater dynamics and the geochemical features are influenced by changes in lithology and by large changes in relief at both a regional and a local scale. Numerical modeling suggested that the dissolution of carbonate minerals, cation exchange, and mineral hydrolysis are the main geochemical processes that support the chemical groundwater composition. Although the variation in As concentrations does not follow clear trends associated with major ion chemistry, laboratory batch tests, and geochemical modelingσ supported by statistical analysis indicated, As solubility is favored under alkaline and high pH conditions. Thus, the As values would be closely related to the desorption from the surfaces of oxides and hydroxides, due to the change in their net surface charge from positive to negative as the pH increases. The Eh–pH conditions show that the main species in solution are HAsO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉. The results suggest a need to carry out epidemiological and toxicological studies which are scarce or even absent in the South of Córdoba province.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Although groundwater and surface water are often treated as individual water compartments in hydrological cycle studies, they essentially originate from one source. Such a split approach restricts the optimal usages of these water resources in several water management applications. The present study aims to shed light on the complex interaction of surface–groundwater interactions in terms of groundwater recharge from drainage network towards the adjacent aquafer and conversely, groundwater discharge from the aquifer towards the drainage network in the Gharehsoo River Basin (GRB), with the enclosed Ardabil aquifer, located in northwest Iran. To that end, the Soil and Water Assessment Tool (SWAT), as the surface hydrological model was fully coupled with the latest version of the Modular Three-Dimensional Finite-Difference Groundwater Flow (MODFLOW-NWT) (Newton–Raphson Technique to improve the solutions of unconfined groundwater-flow problems). The total study period, i.e. 1978–2012 was split into two intervals for calibration (1988–2012) and validation (1978–1987). To facilitate and expedite the calibration of the coupled model, first we calibrated SWAT and MODFLOW-NWT independently against the observed streamflow and groundwater head time series, respectively. Afterwards, we recalibrated the coupled model SWAT-MODFLOW. To link these two models, the surface and sub-surface water flow components are exchanged between the Disaggregated Hydrological Response Units (DHRUs) of SWAT with the MODFLOW-NWT’ grid cells. In addition, three more flow components are sequentially exchanged: the deep percolation from SWAT to MODFLOW-NWT, baseflow/groundwater discharge from MODFLOW-NWT to SWAT, and the river heads from SWAT to MODFLOW-NWT. The results of the application show that the coupled model satisfactorily, quantified by 〈em〉R〈/em〉〈sup〉2〈/sup〉 ≥ 0.5, simulates streamflow and particularly, groundwater heads. In fact, both observations and simulations indicate that, owing to an ongoing overexploitation of the aquifer, heads have been decreased steadily over the studied period which has led to a parallel decline of the groundwater storage. Moreover, the analysis of the stream–aquifer exchange flows indicates that groundwater discharge towards the stream-network (effluent conditions) is orders of magnitude higher than the opposite process (influent conditions). In addition, findings reveal that many of the tributaries across the GRB have shifted from a perennial regime to ephemeral/intermittent system over the past decades. The provided and well-tested coupled model would be a viable asset to assess a wide range of plausible scenarios to identify most effective and practical water resource management schemes to recover the severely depleted surface water and groundwater resources of the GRB.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The mechanical properties of coal are important parameters for coalbed methane (CBM) extraction and gas outburst control. However, the effect of adsorbed gas on strength cannot be evaluated quantitatively yet. To better understand the weakening mechanisms of free and adsorbed gas on the strength of coal, normal coal, and deformed coal are chosen to test their mechanical properties of CH〈sub〉4〈/sub〉-saturated and non-gas-saturated specimens under different conditions. Under the same effective stresses, the peaks of strength of CH〈sub〉4〈/sub〉-saturated specimens with high-pressure gas are lower than those with low-pressure gas, implying that the adsorbed gas can also weaken the peak strength of coal. Then, a new model for the weakening values of strength induced by free and adsorbed gas was developed, and the effects of free gas and adsorbed gas on the strength of coal were assessed by our model. The results show that the free gas and adsorbed gas can weaken the strength of coal for different weakening mechanisms. The ratio of weakening value of strength due to free gas to that of adsorbed gas of the normal coal is 1.3–3.4, and that of the deformed coal is 8.4–19.8. These results can help us to better understand why the weakening effect of adsorbed CH〈sub〉4〈/sub〉 in the laboratory is ignored in earlier studies.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Deep injection disposal of liquid hazardous waste into aquifers confined from top and bottom by low permeable rock layers is examined. The injected waste represents aqueous solutions which are more dense than the reservoir water. Since the aquifer is not strictly horizontal, heterogeneity of the groundwater density causes a resultant buoyancy force which is directed down the dip of the aquifer. We considered a mathematical model of the contaminant plume movement taking into account both topography-driven (regional) and buoyancy induced components of the groundwater flow. Boussinesq’s approximation is used. A simple analytical solution, which is obtained by general functions theory, permits to determine conditions when the buoyancy forces suppress the regional flow what can substantially increase safety of the injection disposal. The obtained result is applied to analysis of contaminant plume movement at injection disposal site of liquid radioactive waste from Siberian Chemical Plant in Tomsk region. A numerical modeling of plume movement at the injection site is carried out. Heterogeneity of water transmissivity of the reservoir bed is taken into account as well as heterogeneous relief of its upper and lower boundaries. We showed on the basis of the analytical solution that buoyancy forces caused by elevated salinity of the injected waste and slope of the reservoir bed at the injection site exert a substantial influence on direction of the contaminant plume movement. Numerical modeling of contaminant plume movement is in good agreement with the analytical estimation of the buoyancy forces influence. Velocity of the regional groundwater flow is directed to the southwest of the injection site. However only dilute solutions are carried southwest by the regional flow. Dense solutions move westward because the buoyancy forces hamper southern component of the regional flow. This leads to an increase in travel time of a substantial part of the radionuclides to the river what increases safety of the injection site.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Estimating the lake level dynamics accurately on a daily or finer timescale is important for a better understanding of ecosystems, especially the lakes in Badain Jaran Desert, China. In this study, lake level dynamics of Sumu Barun Jaran are simulated and predicted on a 2-h timescale using the deep learning (DL) model, which is structured for the first time in this area by considering critical environmental factors. Two machine learning methods, namely multiple linear regression (MLR) and the three-layered back-propagation artificial neural network (ANN), are also adopted for the prediction purpose. The performances of these models are evaluated by comparing the values of average relative error, the mean squared error, and the coefficient of determination. The result shows that the DL model performs better than MLR and ANN on these three criteria, and this DL model is beneficial for exploring the mechanism of lake level dynamics in Badain Jaran Desert.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Seismic refraction has been utilized widely in the past to characterize shallow aquifers and subsurface layers. This study applies the method on a water-shed scale to get information on the regional groundwater flow system. Furthermore, the application of seismic refraction for groundwater and hydrogeologic studies has not been done before in Brunei Darussalam. The country of Brunei Darussalam, located in the North of Borneo, uses more than 99% of surface water resources for its industry and public consumption, with the remaining groundwater resources currently unexplored. However, the ever-increasing population and national industrialisation are putting more pressure on Brunei’s water resources. In view of finding new groundwater reserves, we incorporate seismic refraction methods to characterize the local subsurface layers and to delineate the groundwater levels at the Berakas Forest Reserve, located in the North-East of Brunei. The site is chosen based on its surface geological suitability for groundwater reservoirs as well as the occurrence of springs and ephemeral streams in the area. Initial investigations indicate that the near-surface lithology of the study area has good aquifer potential, with the occurrence of conglomerate and sand deposits formed by braided and meandering rivers during late Miocene to Pliocene. We carried out four seismic surveys at strategic locations with different elevations and distances to the sea. The interpreted water table elevations from the velocity-depth profiles are compared with the actual ground elevations of observed springs as well as an ephemeral stream. The interpretations from the velocity profiles were verified using 1D multichannel analysis of surface waves at selected locations. In addition, seismic tomography was used to investigate the capillary fringe zone, indicating the presence of clayey and silty sediments in the saturated and vadose zone. Our interpretations show that the water table varies with topographic elevation and distance from the South China Sea, as the overall flow direction is towards the sea. The hydraulic gradient is calculated to be 0.04. Water samples collected from springs indicate fresh water based on density of 1.00 g/cm〈sup〉3〈/sup〉 and chloride content below 150 ppm. However, the shallow aquifer is impacted by low pH values and high sulphate concentrations likely due to local acid sulphate soils present in the study area. No saltwater intrusion is expected which is investigated using the Ghyben–Herzberg relationship.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Rocky desertification is a severe ecological issue threatening and constraining regional sustainable development in karst mountainous areas like Houzhai River Basin in southwestern China. The results indicate that slope gradient and altitude are closely associated with occurrence of rocky desertification in the study region and there are some significant correlations between rock outcrop and slope gradient (〈em〉r〈/em〉 = 0.363, 〈em〉p〈/em〉 〈 0.001) and between rock outcrop and altitude (〈em〉r〈/em〉 = 0.0.336, 〈em〉p〈/em〉 〈 0.001). Slope gradient and altitude are key factors contributing to rocky desertification in the studied basin. Therefore, special attention should be paid to sloping lands that have greater slope gradients or altitudes to prevent and control the rocky desertification in a karst mountainous basin as the Houzhai River Basin. Furthermore, it might be possible to predict the occurrence of rocky desertification using neural networks on the basis of geographical characteristics and human disturbance. The correlation coefficients between observed values and predicted values ranged from 0.728 to 0.905, with a mean value of 0.851 (ten times repeats). The present study also indicates that human disturbance has little effect on rocky desertification. However, further studies should be conducted to interpret the effects of agricultural activities on the occurrence of rocky desertification.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The hydrologic characteristics of the Oak Openings Region in northwest Ohio, USA, a globally rare ecosystem are not well understood. Currently, the Oak Openings supports globally rare oak savanna and wet prairie habitats. The wet prairies in the region have been drained by ditches and encroached by invasive plants, which have altered the natural flow making it an unusually variable and artificial system. A shallow groundwater model was implemented using the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) software to simulate continuous, long-term groundwater and surface water interaction in a small subwatershed in the Oak Openings Region. The implemented GSSHA model simulates physical processes such as infiltration, evapotranspiration, snowmelt, overland flow, and interaction of groundwater with ditches. The model was calibrated using a time series of water table elevations collected in the field. Although the model tends to slightly underestimate water table elevations (mean and standard deviation percent differences of less than 1%), statistical analysis indicate a good fit between observed and simulated water table elevations (Nash Sutcliffe Efficiency Index of 0.78). The model would be a useful tool for the preservation of natural areas such as wet prairies.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The main topic of this research was to evaluate the effect in the performance of stochastic landslide susceptibility models, produced by differences between the triggering events of the calibration and validation datasets. In the Caldera Ilopango area (El Salvador), MARS (multivariate adaptive regression splines)-based susceptibility modeling was applied using a set of physical–environmental predictors and two remotely recognized landslide inventories: one dated at 2003 (1503 landslides), which was the result of a normal rainfall season, and one which was produced by the combined effect of the Ida hurricane and the 96E tropical depression in 2009 (2237 landslides). Both the event inventories included shallow debris—flow or slide landslides, which involved the weathered mantle of the pyroclastic rocks that largely outcrop in the study area. To this aim, different model building and validation strategies were applied (self-validation, forward and backward chrono-validations), and their performances evaluated both through cutoff-dependent and -independent metrics. All of the tested models produced largely acceptable 〈em〉AUC〈/em〉 (area under curve) values, albeit a loss in the predictive performance from self-validation to chrono-validation was observed. Besides, in terms of positive/negative predictions, some critical differences arose: using the 2009 extreme landslide inventory for calibration resulted in higher sensitivity but lower specificity; conversely, using the 2003 normal trigger landslide calibration inventory led to higher specificity but lower sensitivity, with relevant increase in type-II errors. These results suggest the need for investigating the extent of such effects, taking multitrigger intensities inventories as a standard procedure for susceptibility assessment in areas where extreme events potentially occur.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Heavy metals in industrial wastes do worldwide significantly influence surface waters, soils, and human health. The relationships between geochemical stream sediment composition and industrial pollution by phosphate mud flood were examined to assess the severity level of the heavy metal contamination due to the mining activities in the Gafsa-Metlaoui basin (Tunisia). A statistical approach based on linear correlations and principal components analysis of 8 metal contents was used in stream sediment, which was applied to 21 samples of surveyed Metlaoui stream. Within the final model, four Eigen factors did explain almost 90% of the total variance matrix (〈em〉F〈/em〉1: 42.25%, 〈em〉F〈/em〉2: 19.60%, 〈em〉F〈/em〉3: 15.50 and 〈em〉F〈/em〉4: 10.15%). Three main metal associations were found in the Metlaoui stream sediment. The first was concerned with Titanium (Ti) and Zirconium (Zr) as conservative elements. The second related to the important role of Manganese (Mn) with Iron (Fe) hydroxides in fixing metals. Finally, the third one consisting of Zinc (Zn), Nickel (Ni), Copper (Cu) and Molybdenum (Mo) is all known to be linked to local mining activities sources. The overall degree of contamination was in the following order (high to low): Ti 〉 Zr 〉 Zn 〉 Mo 〉 Mn 〉 Ni 〉 Fe 〉 Cu, but the extent of the contamination did decrease downstream from the mining activity. Phosphate mining activity, especially washing phosphate, leads to an unwanted heavy metals contamination in the nearby surrounding environment.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This paper deals with impact of geomorphic responses such as thalweg shifting, sandbar instability, pool-riffle alteration, river bank erosion, channel incision river bed lowering and river bank erosion on riverine land cover dynamics arises by instream and floodplain sand mining in an alluvial reach as Kangsabati River from Mukutmonipur dam to Rajnagar confluence (193 km) during 2002–2016. Four segments i.e. Lalgarh, Mohanpur, Kapastikri and Rajnagar share as 554,656 m ton/year sand from 141 mining sites whereas others segment as Khatra, Raipur, Dherua and Panskura share only 33,497 m ton/year sand from 50 mining sites in the entire channel. Several maps were prepared to identify consequences of morphological responses with the help of field study and GIS technique. Friend and Sinha’s method (Geol Soc Lond 75(1):105–111, 1993) was used to detect planform change with geomorphic responses throughout the course. Pearson correlation matrix is used to establish the relation between geomorphic responses and land cover dynamics incorporates with mining intensity. The result shows that higher value of geomorphic responses decrease sandchar, riparian area but increases channel, mining, pits and clay cover in mining prone segments as Lalgarh, Mohanpur, Kapastikri, and Rajnagar. The lower value of geomorphic responses increase sandchar, riparian area but decreases channel, mining, pit sites and clay cover in sandchar segments as Khatra, Raipur, Dherua and Panskura, respectively. Therefore, sand mining greatly impact on riverine land covers dynamic following instable geomorphic responses. Moreover, this study reveals that sustainable sand mining incorporates with stable geomorphic responses maintain fluvial dynamics controlling of erosion and deposition process.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The occurrence of landslide has correlations with the atmospheric temperature change. Assessing the influence of changes in atmospheric temperature on landslides is helpful for the landslide treatment. This study simulates rainfall infiltration in a homogeneous soil slope under varying atmospheric temperatures based on water–air two–phase flow theory and the heat transfer equation. The safety factor of a slide slip is calculated using the residual thrust method under different atmospheric temperatures. The results show that changes in atmospheric temperature affect the seepage field of a slope, possibly affecting the slope stability. Under the same initial and rainfall conditions, the higher the atmospheric temperature is, the higher the rainfall infiltration rate; the deeper the infiltration depth is, the higher the air pressure in the slope and the lower the slope safety factor. Numerical simulations show apparent correlations between atmospheric temperature changes and the safety factor of a slope. Thus, the higher the atmospheric temperature is, the lower the safety factor of a slope. Under certain conditions, changes in atmospheric temperature may trigger landslides.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The Earth’s atmosphere and oceans are largely determined by periodic patterns of solar radiation, from daily and seasonal, to orbital variations over thousands of years. Dynamical processes alter these cycles with feedbacks and delays, so that the observed climate response is a combination of cyclical features and sudden regime changes. A primary example is the shift from a glacial (ice age) state to interglacial, which is driven by a 100-thousand year orbital cycle, while the transition occurs over a period of hundreds of years. Traditional methods of statistical analysis such as Fourier and wavelet transforms are very good at describing cyclical behavior, but lack any characterization of singular events and regime changes. More recently, researchers have tested techniques in the statistical discipline of change point detection. This paper explores the unique advantages of a piecewise linear regression change point detection algorithm to identify events, regime shifts, and the direction of cyclical trends in geophysical data. It evaluates the reasons for choosing this particular change detection algorithm over other techniques by applying the technique to both observational and model data sets. A comparison of the proposed change detection algorithm to the more established statistical techniques shows the benefits and drawbacks of each method.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Groundwater in a shallow aquifer used for potable supply in Qingdao, China, has been contaminated by nitrate by the excessive use of chemical fertilisers for vegetable production in the area. In this study, a representative site was selected to construct a non-continuous permeable reactive barrier (PRB) back-filled with a mixed reactive medium containing of zero-valent iron, activated carbon and medium- to coarse-grained sand. The PRB consists of alternate well and pillars and was constructed to provide a funnel and gate treatment system for two pumping wells. Groundwater monitoring during a trial of the system indicated that the concentrations of nitrate in monitoring wells within the treatment system rapidly declined (within a day) from about 120 mg/L to 20 mg/L. Reductions in nitrate concentrations were also observed in the pumping wells and downgradient monitoring wells, but changes in nitrate concentrations were moderated by mixing with contaminated groundwater. The PRB construction technique of using alternative wells and pillars combined with jet grouting was found to be effective for nitrate removal from groundwater at a small scale.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Hydrogeological and thermogeological properties of the shallow subsurface in the Dinaric karst area of Croatia were investigated in the context of its utilization for ground- and water-source heat pumps (GSHPs and WSHPs). The research encompassed four 100 m deep boreholes with GSHP installations in both coastal and inland Dinaric karst (different limestones and evaporitic rocks at one location), and a set of six exploratory boreholes, abstraction and reinjection wells for WSHP heating and cooling using seawater on the coast (fractured and karstified limestones). It was determined that rock thermal conductivities are favourable for GSHP utilization, but dependent on the wider rock mass characteristics which are hard to predict (size of karst voids and their saturation status). In addition, wells with high enough yield and stabile seawater or groundwater temperatures for WSHP utilization can be designed in appropriate structural settings (tensional fractures and fracture set intersections). Advantages and disadvantages of the utilized methodology have been pointed out, as well as methods which should prove useful in the future, especially if larger systems are planned. Hydrogeological, geotechnical, and thermal risks expected during the drilling, installation, and operational phases have also been identified. Presented case studies have given the insight into heat pump installation options and conditions in Croatian part of the Dinarides, but can be useful to other researchers and engineers both in the Dinarides and in similar karst regions.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Natural and human-induced groundwater dynamics in hyper-arid aquifers play a crucial role in the evolution of the landscape. The area overlying the Saq Aquifer, in particular the Al-Qassim area within the central part of the Kingdom of Saudi Arabia, has witnessed numerous land deformation (land subsidence and fissures) events throughout the last two decades. An integrated remote sensing and hydrogeologic approach is adapted to identify areas affected by the land deformation and also to better understand the role of human-induced groundwater dynamics in the formation of these deformation features. A fourfold approach was implemented including: (1) conducting field surveys to collect observations and validate the reported deformation features, (2) applying a spatial correlation in a GIS environment for the reported damaged locations together with surface and subsurface geological features and groundwater extraction. (3) extracting the subsidence rates using SBAS radar interferometric technique using ENVISAT data sets, and (4) correlating these subsidence rates spatially and temporally with GRACE mass variations data. The results show that high subsidence rates of − 5 to − 12 mm/year along a northwest–southeast direction coincident with areas witnessing a significant drawdown in the fossil groundwater levels (up to 150 m) and a depletion (−10.1 ± 1.2 mm/year) in GRACE-derived terrestrial water storage. Findings from the present study draw attention to the quick responses of landscapes to human-induced groundwater dynamics under hyper-arid conditions.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The instability of rock slope in the freeze–thaw mountains has abrupt and uncertain characteristics, and its prediction accuracy often is very low. How to accurately estimate the stability of this kind of rock slope is an urgent problem to be solved. In this paper, we presented the evaluation method of rock slope stability in the freeze–thaw mountains coupling the hierarchy analysis, the rough-set theory and the genetic algorithm. Fifty highway rock slopes in Taishun county of Zhejiang province, China, were selected as the examples in the study. The main factors influencing rock slope stability were obtained using the analytic hierarchy process (AHP), and their corresponding weights were given. The evaluation rules were extracted from rock slope instability examples using the hierarchy analysis, the rough-set theory and the genetic algorithm. Then the approximate reasoning method was proposed using the method of inexact reasoning and default inference. The proposed method takes inexact reasoning and default reasoning to deal with incomplete match or absence of information. The results show as follows: it is reasonable and feasible to evaluate rock slope stability using the proposed method; using the proposed method, we can grasp the key factors influencing on rock slope stability, and the reasoning is flexible; the presented method can improve the intelligent prediction accuracy of rock slope instability in the freeze–thaw mountains. It remains to be further studied whether the method presented in this paper is suitable for the stability evaluation of other rock slopes.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉We present the seismic site characterization study using joint modelling of Horizontal-to-Vertical Spectral-Ratio (HVSR) and Rayleigh wave-phase velocity-dispersion curves obtained from Multi-channel Simulation with One Receiver (MSOR) in a part of Dhanbad, Jharkhand, India. The joint analysis of these two different but complementary datasets puts stronger constraints on the model parameter search space than one dataset and may help us in finding more unique shear-wave velocity model. The microtremor data from 12 observation points were utilized to iteratively search 1D shear-wave velocity profiles in a predefined model search space. These 1D shear-wave velocity models were interpolated to generate a 2D shear-wave velocity profile of the site using the cubic spline method. Our results show that the high peak amplitude value of HVSR is associated with low peak-period values of HVSR at a distance of ~ 60 m from the southern end of the profile; which may indicate the presence of the Basin Edge Effect. We identified four layers based on significant changes in the shear wave velocities to a depth of ~ 60 m. The major impedance contrasts are located at average depths of ~ 13 m, ~ 40 m and ~ 55 m, respectively. These layers from the surface may indicate the presence of soil, highly weathered rock mass, moderately weathered rock and bedrock, respectively. The depth of engineering solid bedrock (〈em〉V〈/em〉〈sub〉s〈/sub〉 〉 600 m/s) is found at the depth of 55 m in the south which gradually decreases to a depth of 40 m in the northern end of the profile. The shear-wave velocity (〈em〉V〈/em〉〈sub〉s〈/sub〉 30) for this area varies between 293 and 357 m/s; which can be classified as “D-type site”. For validation and comparison of our results, the Electrical Resistivity Tomography (ERT) data were also recorded along the same traverse using Wenner and Schlumberger configurations. Our results show a significant amount of correlation between the 2D shear-wave velocity and resistivity profiles obtained from joint analysis of tremor and ERT data.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Large-scale mining of coal seams gives rise to the leakage of phreatic water and further deteriorates the ecological environment of arid and semiarid mining areas in Northern Shaanxi Province. The height of the water-conducting fractured zone (WCFZ) in coal mining is the key to evaluating the presence of phreatic water leakage. This paper adopts the running water quantity of boreholes monitoring and distributed optical fiber sensing (DOFS) technology to conduct in situ measurements of the WCFZ height in soil–rock composite structure overburdens. Twenty groups of data were used to analyze the factors which influence the development height of the WCFZ and several equations are proposed to estimate the WCFZ characteristics. As indicated by the study results, the DOFS technology effectively ascertains the height of water-conducting fractures in soil and the soil layer had an obvious inhibitory effect on the height of WCFZ, with an inhibiting factor of about 0.5. The maximum relative error between predicted values and measured values was 5.34% and the relative error between predicted values and numerical simulation results was within 1.5%, verifying the accuracy of the prediction equations. The study results will help avoid water inrush hazards in mining areas and protect mining areas against ecological damages.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The groundwater recharge potential in the West Liaohe Plain in northeast China was assessed using a modified chloride mass balance method to estimate the vertical infiltration of water through typical soil profiles at two study sites in the region: the Horqin Left Middle Banner (KZ) site and the Kailu County (KL) site. Samples of precipitation, groundwater, and soil water were collected at the KZ and KL sites to determine the effects of irrigation and soil texture on water infiltration in soil profiles. The results showed that the water infiltration rate at the KZ site is approximately 6–11 mm/a beneath farmland, with similar infiltration rates for mulched drip irrigation and flood irrigation methods, but the infiltration coefficient with a mulch cover was slightly higher than that of soils without a mulch cover. The infiltration rate in soils at the KL site was determined to be 25–41 mm/a beneath farmland and in this area the infiltration rate and infiltration coefficient in soils with a mulch cover were much higher than in soils without a mulch cover. Additionally, the infiltration rate and infiltration coefficient in sandy-textured soils at the KL site were higher than in clayey soils at the KZ site. The infiltration rate in bare land at the KL site with a similar soil texture to that of the farmland was determined to be approximately 16 mm/a, or approximately one-half the infiltration rate measured beneath the farmland. Water infiltration rates in cultivated soils were higher than those beneath non-cultivated areas; however, this does not mean that the actual groundwater recharge rate increased. The amount of irrigation water used is lower using mulched drip irrigation than in fields irrigated using flood irrigation, but the infiltration coefficient actually increased. This suggests that the mulched drip irrigation method can increase groundwater recharge in semi-arid regions such as the study area.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The mining activity in Peru is of long standing and its existence begins with the times and cultures pre Incas, Inca, colonial and the own Republic. This is due to the existence of deposits and important mineral resources distributed throughout the Peruvian territory. This paper reports a study focusing sediment profiles (LKS-1, LKS-2 and LKS-3) and water samples collected in Ramis River that is located in Ananea District, Puno Department, in southern Peru at the northern section of Titicaca slope. The CF:CS 〈sup〉210〈/sup〉Pb chronological model allowed determine sedimentation rates useful for evaluating the history of the heavy metals contamination over the past 150 years in that mountainous area of the Peruvian Altiplano. The maximum concentration of As, Cr, Cu and Zn was, respectively, 400, 93, 93 and 20 ppm (LKS-1); 120, 95, 98 and 20 ppm (LKS-2); 98, 98, 87 and 40 ppm (LKS-3). Two linear sedimentation rates were identified in each profile along Ramis River: 0.14 and 0.15 cm/year (LKS-1); 0.33 and 0.21 cm/year (LKS-2); 0.31 and 0.24 cm/year (LKS-3). The respective deposition times were: LKS-1 = 76 and 177 years; LKS-2 = 85 and 130 years; LKS-3 = 86 and 144 years. Possible events related to the different rates would be the degradation of the native forest by anthropic actions, characterized by the activities of overturning and burning to carry out forest plantations, as well active processes taking place in the region like the urban growth.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In Brazil, alkaline intrusions are source rocks for several commodities (bauxite, phosphate, niobium and barite, to mention a few), including mineral water. The present study aims to understand by means of chemical and stable isotope analyses, the residence time, circulation and hydrochemical facies of the groundwater systems from the alkaline–carbonatitic complex of Barreiro (State of Minas Gerais, Brazil). This Mesozoic alkaline complex is located in the Brazilian tropical region characterized by weathered soils and fractured rocks, which play an important role in the groundwater dynamics. To assess this influence, groundwater samples from 12 points and water samples from 3 artificial lakes were collected for the determination of chemical element and natural isotope (〈sup〉18〈/sup〉O, deuterium and 〈sup〉13〈/sup〉C) concentrations and 〈sup〉14〈/sup〉C and tritium dating. Two main groundwater categories were revealed: (a) a local, acidic and sub-modern groundwater system developed in thick, poorly mineralized weathered soil from the inner part of ACCB, and (b) a basic, hypothermal, ca. 40-ky-old fractured aquifer developed in mineralized fenitized quartzites. The younger and shallower groundwater circulation is controlled by the present intrusion relief and is prone to environmental impacts. The older, hypothermal groundwater system indicates existing geothermal residual heat provided by the Mesozoic alkaline intrusion.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Measurements were made at the destroyed nuclear reactor IRT-5000 (14-Tammuz research nuclear reactor at AL-Tuwaitha Nuclear Center in Iraq) to provide a basic comprehensive radiological characterization and to assess risk and dose for the workers in the workplace. Samples were collected from the site and analyzed, as well as using a portable survey meter to determine the external exposure dose rates. The quantity and quality of radionuclides were determined using gamma spectrometry techniques. The dose rate measured within the reactor core body ranged from 55 to 1250 mSv/h. The maximum dose was recorded in the middle of the corner near the horizontal experimental channel number seven, with activity concentration of 19.97 GBq estimated from Co-60 isotope. Most samples were contaminated with Cs-137, Co-60, and Eu-152 isotopes. The highest activity concentration of Cs-137 is 14772.41 ± 99.91 Bq/L and Co-60 is 7642.22 ± 40.02 Bq/kg, were found in slag from reactor tank. Two scenarios were developed based on the water level of the reactor tank. Assuming there are three locations for workers on the reactor surface. The annual dose of workers on the surface of the reactor (when the reactor tank is empty) ranges from 116 to 153 mSv, which is higher than the annual dose limit for workers. Therefore, workers will be subjected to the principle of As Low As Reasonable Achievable (ALARA) during all phases of dismantling nuclear reactor IRT-5000 (14-Tammuz) as recommended by International Atomic Energy Agency (IAEA).〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this study, we developed a parameter estimation method of a reservoir conservation model that was developed by the World Bank for efficient sediment flushing operation in dam reservoirs. The parameters for sediment flushing operation are flushing discharge, duration, frequency, and necessary reservoir drawdown. The parameter estimation method was applied to Shahpur Dam in Pakistan, in which sediment balance ratio and long-term capacity ratio were used as indicators of flushing efficiency. For efficient flushing of Shahpur Dam, we recommended that bottom outlets at the dam be retrofitted to achieve a flushing discharge of 7.5 m〈sup〉3〈/sup〉/s. The reservoir water elevation should be drawn to a minimum level of 430 m, and the flushing operation should be performed annually over a 15-day span. Flushing using these parameters would result in 100% sediment balance, with 69% of original dam capacity recovered in the long term. We also assessed constraints on dam site for successful flushing. The drawdown ratio was 0.72, sediment balance ratio at full drawdown was 1.58, flushing width ratio was 0.88, and top width ratio was 1.23. For every increment of 0.5 m〈sup〉3〈/sup〉/s in flushing discharge, the amount of sediment flushed increased by 0.020–0.025 million tonnes. This method can provide guidelines for implementation of sediment flushing operations for reservoir sediment management.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉During urbanization, different dimensions of the expansion of construction land causes different degrees of surface deformation. Based on the C-band ENVISAT ASAR data (December 2004 to September 2010) and Sentinel-1A data (March 2015 to April 2017), the small baseline subset interferometric synthetic aperture radar (SBAS InSAR) method was used to monitor the spatial and temporal variations of surface deformation in Shanghai, China. The results showed that widespread uneven subsidence occurred in Shanghai from December 2004 to April 2017. A transition from urban areas toward the suburbs appeared in the spatial distribution, in which the cumulative deformation in the urban areas has the characteristics of seasonal fluctuation, which shows the alternation of subsidence and rebound. In addition, the deformation characteristics of different types of construction land with the same geological conditions were compared, which showed that residential land had the least cumulative subsidence and clear seasonal fluctuations, industrial land had the greatest cumulative subsidence, and transportation land had greater subsidence during the construction period but tended to become stable after being put into use. This suggests that the deformation characteristics of Shanghai are changing, and the type of construction land is also an important factor in the deformation process.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The decrease of fresh water supply from connected rivers induces the reverse of gravity flow from Bizert Lagoon which increases the salinity and the total suspended matter (TSM). Therefore, multi-date 〈em〉MODIS〈/em〉 images were analyzed by GIS to calculate and identify the spatial distribution of WTI, TSM indicator. Then, the relationship between wind conditions and TSM’s resuspension in Ichkeul Lake was clarified. After that, the cluster analysis and the temporal fluctuation of daily wind speed; rainfall, and the 〈em〉Potamogeton pectinatus〈/em〉 phenology were used to interpret the seasonal distribution of the turbid water. Consequently, the linear correlation between WTI and observed data was found (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.66; 〈em〉r〈/em〉 = 0.809) and proved by ANOVA test, where 〈em〉P〈/em〉 = 0.00143 (〈 〈em〉α〈/em〉 = 0.05). Besides, the prevailing effects of winds on turbidity were detected, where the daily mean value of WTI was positively correlated with daily wind speed with 〈em〉r〈/em〉 = 0.63 and 〈em〉r〈/em〉 = 0.65, respectively, for P1 and P2. Thus, the turbidity increases with the increase of wind velocity. Subsequently, wind speed threshold was chosen to be 2.8 m/s. Moreover, the frequent wind with velocity varied between 5 and 7 m/s and may exceed the 9 m/s blew from the WNW direction. Added to this, the seasonal distribution of WTI revealed that the most and moderate turbid days were detected frequently in summer season. Following the prevailing wind direction, the TSM was distributed from the center of the SSE part of Ichkeul Lake.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Liquid carbon dioxide has an excellent ability of endothermic cooling and inhibition on coal fire, which was an effective coal spontaneous combustion prevention technology. To analyze the oxidation characteristics and variation of apparent activation energies, a carboniferous–permian coal sample was investigated in O〈sub〉2〈/sub〉/N〈sub〉2〈/sub〉 and O〈sub〉2〈/sub〉/CO〈sub〉2〈/sub〉 atmospheres by the coal spontaneous combustion oxidation and the Fourier transform infrared spectroscopy experiments. The results indicated that with temperature, carbon monoxide (CO) concentration and oxygen (O〈sub〉2〈/sub〉) consumption rate increased. While O〈sub〉2〈/sub〉 concentration decreased, CO concentration and oxygen consumption rate reduced. At the same O〈sub〉2〈/sub〉 concentration, the oxygen consumption rate and CO concentration on the O〈sub〉2〈/sub〉/CO〈sub〉2〈/sub〉 atmospheres were less than on the O〈sub〉2〈/sub〉/N〈sub〉2〈/sub〉 atmospheres. Therefore, O〈sub〉2〈/sub〉 concentration reduced, or added CO〈sub〉2〈/sub〉 significantly inhibited coal oxidation. As the temperature elevated, the apparent activation energy gradually increased. Furthermore, the apparent activation energy increased when the oxygen concentration reduced in the physical–chemical adsorption stage and the slow oxidation stage. In the rapid oxidation stage, the apparent activation energy lessened with increase in oxygen concentration. Through correlation analysis, the key functional groups in the physical–chemical adsorption stage were hydroxyl, C–O, –COO–, and aliphatic hydrocarbons. During the slow oxidation, the key functional groups were –COO– and aliphatic hydrocarbons. The key functional groups in the rapid oxidation stage were hydroxyl and C–O.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Desertification has been listed as the top of ten major problems affecting global environmental changes, and represents one of the important reasons of semi-arid grassland degradation. It is therefore crucial to understand ecological environment of semi-arid grasslands and temporal and spatial changes in real time for regional and local environmental protection and management. At present, remote sensing technology is being widely used in monitoring and evaluation of land desertification due to its wide observation range, large amount of information, fast data updating and high accuracy. It represents an advanced method for remote sensing monitoring of desertification by extracting various indicators and constructing feature space. Based on this, this study used Landsat images and field survey data to establish a desertification index (SASDI) model based on the albedo-MSAVI (Modified Soil Adjusted Vegetation Index) feature space and analyze the relationship between desertification and surface quantitative parameters in semi-arid grassland area. Results show that the SASDI model has a high correlation (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.7585) with the organic matter in the soil surface and makes full use of multi-dimensional remote sensing information. The index reflects the surface cover, water, and heat combination as well as changes of the desertification land, with a clear biophysical significance. Moreover, the index is simple and easy to obtain, facilitating to quantitative analysis and continuous monitoring of desertification in semi-arid grasslands.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In the last few decades, with the development of computers and geographic information system (GIS), a wide range of landslide susceptibility zonation (LSZ) techniques were orchestrated by various researchers around the globe. Among them, the artificial intelligence (AI) have been distinctly regarded as the most effective and suitable approach to part with GIS for LSZ. Though, suitability of AI for LSZ is well addressed in the landslide literature, noises of processing data, choice of causative factors and landslide density of study area are the number of hindrances that cause quandary over preference of ideal AI technique among many. The current study intends to analyse and compare the predictive performance of two entirely different AI techniques, fuzzy expert system (FES), a bivariate statistical technique, and extreme learning machine (ELM), a multivariate statistical technique for GIS based LSZ. The Mussoorie Township, a famous tourist destination in the Indian State of Uttarakhand was taken as the study area. Thematic layers of relevant causative factors and landslide inventory were prepared for the study area through field survey, remote sensing, and GIS. The resultant landslide susceptibility maps (LSM) of the study area, LSM-I of FES and LSM-II of ELM were critically evaluated and compared with the aid of landslide inventory of the study area.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In the study, a self-developed Split Hopkinson pressure bar apparatus with triaxial confining pressure was used to examine the dynamic compression property of salt rock under confining pressures of 5, 15, and 25 MPa. To examine the dynamic properties of salt rock, Yingcheng salt rock from Hubei province in China was considered. Dynamic stress–strain curves of salt rock under different confining pressures and strain rates were obtained. The results indicated that the peak stress and ductility of salt rock increased with increase in the strain rate although the strain rate strengthening effect of the salt rock was not evident with increase in the confining pressure. The dynamic properties and disintegration characteristics were investigated on the basis of the energy dissipation principle. The energy delivery and transformation in the entire experimental process were analyzed in detail. Under the same confining pressure, the hardening effect of the salt rock was more evident with increase in the incident energy, and this can be explained by the decrease in the energy transmission/absorption rate when the reflectance rate increased. Contrary to the plastic damage characteristics under quasi-static triaxial compression, the salt rock exhibited evident brittle fracture characteristics under dynamic compressive loading. The peak stress of the salt rock revealed different trends with the increase in energy absorption under different confining pressures. Increased energy absorption and higher peak stress were observed under low confining pressure. However, the peak stress significantly decreased with increase in the energy absorption under high confining pressure.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Future climate change and the temporal variability of water availability may cause the deterioration of groundwater quality and increase depths to water tables. In this study, groundwater quality data of 347 monitoring sites from 2003 to 2016 from a region in Pakistan were used to analyze the spatiotemporal variability in different water quality parameters using the Mann–Kendall and Sen’s slope estimator tests. The results indicated a significant increasing trend (SIT) at 23% sites in pre-SAR (sodium adsorption ratio during the pre-monsoon season) and at 22% sites in pre-EC (electrical conductivity during the pre-monsoon season) over the entire study period. The spatial distribution modeling of groundwater quality trends indicated that a significant increasing trend was observed in EC at most of the monitoring sites during the pre-monsoon season (〈em〉α〈/em〉 = 0.05). The area with significant increasing trend of groundwater EC and SAR values increased during the pre-monsoon season and decreased during the post-monsoon season. A continuous significant increasing trend in EC and SAR was observed in the northern part of the study area during the period 2003–2016. This trend indicates that excessive groundwater abstraction in the area is causing adverse impacts on groundwater quality, and that management measures need to be urgently implemented to limit further degradation of groundwater quality.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉With the increase of water consumption and deterioration of water quality in the arid region of China, attention has been raised on issues such as the selection of water sources, water resources protection and water source protection. Based on the surface water samples of Xiying River Basin in the upper reaches of Shiyang River from June 2015 to May 2016, the sampling period is once a month for 1 year. At the same time, combined with the same-day runoff and precipitation data of Nine Ridges Hydrological Station at Xiying River outlet, the influence of runoff process on Hydrochemistry in Xiying River upstream was analyzed using Piper triangle diagram, Gibbs diagram and PCA. The results show that: (1) The surface water is generally weak alkaline, mainly enriched with Ca〈sup〉2+〈/sup〉 and 〈span〉 〈span〉\({\text{HCO}}_{3}^{ - }\)〈/span〉 〈/span〉, and the water type is generally Ca–HCO〈sub〉3〈/sub〉. (2) The seasonal variation of inorganic ion concentration is very obvious. Ion concentration is high in winter and spring, but low in summer and autumn. (3) Because erosion and transport of rock weathering by runoff process are the main source of runoff ion, the ion concentration in watershed water varies significantly in space, gradually enriched with altitude from high to low, especially Ca〈sup〉2+〈/sup〉, 〈span〉 〈span〉\({\text{HCO}}_{3}^{ - }\)〈/span〉 〈/span〉. (4) Ion concentration is positively correlated with precipitation and negatively correlated with runoff in the same period.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The Jinan spring area is one of the fastest developing and most water-stressed regions of China. Because of rapid urban expansion, groundwater recharge has been greatly influenced by land-use/cover change (LUCC). To gain an improved understanding of how the groundwater recharge affected by LUCC from 1960 to 2015, normal years, including 1985, 2000, and 2015, were selected using the Pearson-III distribution. Land-cover types of the normal years were classified using Thematic Mapper images. A loose coupling of an urban expansion model and a hydrological model was used to quantify the impact of LUCC on groundwater recharge. The results showed that land converted to built-up land was mainly mixed forest and arable land. The proportion of land-use types that remained unchanged was generally less than 50%, except for built-up land. In 2030, the area of built-up land will continue to increase, while the area of arable land and mixed forest will decrease correspondingly. The mean annual groundwater recharge was 88.32, 87.95, 73.31, and 76.17 mm for 1985, 2000, 2015, and 2030, respectively, which accounts for 14.01, 12.90, 12.20, and 11.98%, respectively, of the annual precipitation. In the water balance of the study area, only a small fraction (11.98–14.01%) of precipitation recharges the groundwater, and the remainder is lost by evapotranspiration (81.41–82.05%) and to a lesser extent by surface runoff (4.15–6.83%). The amount of groundwater recharge is mainly controlled by precipitation and potential evapotranspiration. Recharge is negatively correlated with the drought index. The ratio of groundwater recharge to precipitation decreased at a rate of − 0.06% from 1985 to 2015. The recharge/precipitation ratio is expected to decrease by a further 0.22% by 2030. The decrease in the ratio is primarily the result of an increase in built-up land areas, and a decrease in mixed forest and arable land areas.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉South Gujarat, a part of the northwestern Deccan Volcanic Province of India has been experiencing episodic swarm activity with reports of sounds, whose association remains unclear. After the Indian monsoon period, during the month of September 2016, a swarm activity occurred around the Keliya dam in the Navsari district of South Gujarat and nearby villages in the Dadra and Nagar Haveli (DNH), which continued for about 4 months. Again, the swarm activity recurred during the month of August 2017 and continued for about 5 months till January 2018. Many of these events were accompanied by audible sounds, like blasting, that caused severe panic among local occupants. A local network of four stations was installed to monitor the swarm activity, in addition to the Gujarat state seismic network. A total of 1048 earthquakes were located around the Keliya dam and 229 events in the DNH region from September 2016 to June 2018. In the present study, we performed a spectrogram analysis of the events with associated sounds. The analysis revealed significant energy at frequencies ≥ 20 Hz, in the audible frequency range. The relocated earthquake distribution shows that seismicity in the Navsari district follows a ~ NW–SE trend, confined to an area of 13 km × 2 km with a depth extent of 3 km. The trend is similar in the DNH region, confined to an area of 15 km × 2 km, down to a depth of 6 km. The determined focal mechanism in DNH region shows strike-slip faulting. The seismicity patterns seem to corroborate with the trends of the lineaments/dykes in the region. In general, the swarm-type earthquake sequences seem to occur when the annual rainfall exceeds the mean annual rainfall. We speculate that the present swarm activity, noticed with some delay after the Indian summer monsoon season, may be due to the phenomenon of hydro-seismicity.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The time series analysis approach has the ability to recognize the characteristics of a karst aquifer by analyzing the response of the discharge from rainfall in a karst area. The karst aquifer is considered to be a system that influences the response to the conduit, fissure, and diffuse flow. This research was conducted in Mudal, Kiskendo, and Anjani Springs located in the Jonggrangan Karst, Java Island, Indonesia. The objective of this study was to determine the differences in the response of karst aquifers in releasing the flow in these three springs. The data used in this study are paired data of discharge and rainfall, which were obtained from January to November 2018 (〈em〉N〈/em〉 data = 31,408). Discharge data were obtained by installing an automatic water level logger, while rainfall data were obtained by installing automatic rain gauges in each spring. The time series analysis methods that were used are cross-correlation, auto-correlation, cross-amplitude, spectral density, phase functions, and gain functions. The master recession curve (MRC) calculation was performed to confirm the results from the time series analysis. The study reveals that each spring has a different response in releasing the flow components. Anjani Spring has the fastest response to conduit and fissure flows. However, this spring has the longest release duration of the diffuse flow component, indicating that a well-developed karst aquifer can also have high system memory and large storage capacity. Kiskendo Spring has a faster conduit and diffuse flow response than Mudal Spring but has the slowest fissure flow response, reflecting the void fissure that dominates in this site. In addition, MRC confirmed the results of the time series analysis calculation. This MRC analysis also shows that the study sites were categorized as a high sensitivity degree of karst aquifer. The karst aquifer’s characterization in this study can be used as basic data in the water resources management in the Jonggrangan Karst.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉A multiparameter geochemical-isotopic fingerprinting approach was used to differentiate anthropogenic and natural signatures of uranium contamination near the Homestake uranium mill site (Site), near Milan, New Mexico, USA. The Site consists of two tailings piles from milling operations and groundwater contamination from these tailings has been noted. The Site lies within the lower San Mateo Creek Basin and has multiple regional sources of uranium contamination from mining and mill operations. The Site is underlain by a heterogeneous alluvial aquifer, which is in turn underlain by basement rock of the Chinle Group aquifer and the underlying San Andres-Glorieta Formation aquifer. To help decipher signatures, several statistical approaches were used including principal component analysis, non-metric multidimensional scaling, and cluster analysis. Piper diagrams indicate two end-member water types at the Site, sulfate–Na–K generally in the Chinle Group aquifer and sulfate–Ca generally in the alluvial aquifer. There are wells from both aquifers that plot between the two end members. Uranium concentrations from the Site fall into three broad categories: less than the drinking water standard of 30 µg/L (〈em〉n〈/em〉 = 3), from 30 to 100 µg/L (〈em〉n〈/em〉 = 9), and greater than 100 µg/L (〈em〉n〈/em〉 = 8). Component loadings in a principal component analysis are highest for uranium isotopes, uranium, molybdenum, chloride, sodium, 〈sup〉228〈/sup〉radium, and gross alpha–beta, which affect the similarities or differences among wells sampled. Results suggest that several alluvial wells north of the Site have groundwater with anthropogenic fingerprints from regional sources related to upgradient mining. Well water with higher uranium concentrations has uranium activity ratios close to 1, which is indicative of mining or milling signatures. These same wells have elevated radon activities. This information can be used to inform Site managers regarding the source of water related to uranium at the Site and provide an approach for geochemical fingerprinting.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This study describes the removal of Cr〈sup〉3+〈/sup〉 ions from aqueous solutions by magnesium oxide (MgO) and montmorillonite nanoparticles (NPs). Optimum values of contact time, adsorbent dosage, temperature, and pH as well as adsorption isotherms, were obtained using concentrations of the metal ions. A scanning electron microscopy-energy dispersive X-ray (SEM–EDX) technique was used to determine adsorbents characteristics. The results showed the maximum uptake values of solutions, by the final point of isotherm experiments were 1033.8 and 3.6 mg/g for MgO nanoparticles (MgO-NPs) and montmorillonite, respectively. The adsorption process followed pseudo-second order kinetic model. Langmuir adsorption isotherm model fitted better to montmorillonite data (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.9769), and Freundlich isotherm was in a good agreement with MgO experimental data (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.9948). Also, thermodynamic studies were carried out to determine the nature of the process. Thermodynamic results revealed the nature of sorption in MgO-NPs was spontaneous, and in montmorillonite NPs was unspontaneous. Based on the results and by considering the economic aspects of examinations, the MgO-NPs can potentially be used as efficient sorbents for Cr〈sup〉3+〈/sup〉 ion removal from aqueous solutions in different conditions.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The Cretaceous Nubia sandstone aquifer is the main aquifer in East El-Oweinat area along the Egyptian–Sudanese borders and in NE Africa. East El-Oweinat project has been recently considered one of the main agricultural projects in the southwest of the Egyptian Western Desert. So, the hydrogeological assessment for the Nubia aquifer in East El-Oweinat area has been done through studying and characterising the hydraulic parameters and step-drawdown test. The well and aquifer losses coefficients (〈em〉C〈/em〉 and 〈em〉B〈/em〉, respectively), the specific capacity, and the well efficiency as well as the aquifer and aquitard thickness have been estimated and traced through a total of 46 wells that have been distributed through the study area in two sectors, southern and northern. For the purpose of further exploration, the effective porosity (〈em〉∅〈/em〉), hydraulic conductivity (〈em〉K〈/em〉), and transmissivity (〈em〉T〈/em〉) have been estimated for the wells in the northern sector. In addition, an aquifer assessment quality index has been introduced to assess and to rank the studied aquifer. Therefore, it is concluded that the hydraulic and the step-draw down parameters as well as the aquifer and aquitard thicknesses are prospective for further exploration to the north and the east of the northern sector in the study area. The well efficiency is mostly affected by the studied parameters, particularly the well loss coefficient, the hydraulic parameters and the well design as well. GIS approach and ArcGIS software have been applied to delineate the spatial distribution of the well performance characteristics, in order to compare between the studied groundwater wells and to integrate the different-acquired data. A set of isocontour maps have been introduced to match the lateral variation of the studied parameters and the aquifer potential to refer to the best direction for further underground water exploration.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Urmia Lake is one of the greatest salt lakes in the world and is located in the uppermost northwestern regions of Iran. In this study, in addition to trace elements, activity concentration of natural (〈sup〉238〈/sup〉U, 〈sup〉232〈/sup〉Th and 〈sup〉40〈/sup〉K) and artificial (〈sup〉137〈/sup〉Cs) radioisotopes are determined in soil and sediment specimens collected from the Urmia Lake shore by adopting gamma ray spectrometry method. The samples are analyzed for trace elements including heavy metals using atomic absorption and ICP-MS techniques. The activity concentration levels were determined for 〈sup〉238〈/sup〉U (from 8 to 48 Bq kg〈sup〉−1〈/sup〉), 〈sup〉232〈/sup〉Th (from 7 to 64 Bq kg〈sup〉−1〈/sup〉), 〈sup〉40〈/sup〉K (from ≤ MDA to 631 Bq kg〈sup〉−1〈/sup〉) and 〈sup〉137〈/sup〉Cs (from ≤ MDA to 22 Bq kg〈sup〉−1〈/sup〉) with the minimum detectable activity (MDA) of 5, 4, 63 and 4 Bq kg〈sup〉−1〈/sup〉, respectively. It seems that except for the cadmium, all of the elements belong to uncontaminated to low contaminated soils group. The least correlation between 〈sup〉137〈/sup〉Cs and other elements distribution in the area, confirms its anthropogenic man made source. Based on the cluster and factor analysis methods of data processing, 〈sup〉238〈/sup〉U, 〈sup〉232〈/sup〉Th and 〈sup〉40〈/sup〉K belong to a similar group which in addition to their low geo-accumulation indexes can point to their geogenic sources, related to potassic volcanic rocks. Rare earth elements studies revealed that the main geochemical features of the sediment samples of the lake are affected by the intermediate to felsic Cenozoic volcano-plutonic rocks of the region.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This paper introduces the designed calculation course of improvement of the mixed turbine impeller by applying computational aided design/computational fluid dynamics method for hydraulic machinery. Taking the HL220 turbine impeller as an example, the cavitation characteristic of the impeller inlet flow under the large flow was analyzed. Then, some approaches are presented to improve the performance of impeller inlet flow and cavitation by reshaping the blade. In addition, the method to determine the blade form for better cavitation characteristic and the relevant geometric parameter are also presented in this paper.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This study evaluated groundwater pollution from a molybdenum mining site in Jilin province, China. First, groundwater pollution in the study area was evaluated using set pair analysis (SPA), which addresses the uncertainties of the evaluation factors and the complex nonlinear relationship among them. Second, groundwater pollution after 3 years was predicted. In this process, the influence of parameter uncertainty on simulation results was analyzed using Monte Carlo simulation, and the results of the analysis were explained from the perspective of pollution risk assessment. Monte Carlo simulation requires repeated invocation of a simulation model, which creates a large computational load. To solve this problem while ensuring high simulation accuracy, sensitivity analysis was used to select the more sensitive model parameters as random variables, and establish a surrogate model based on the Kriging method, thus facilitating the Monte Carlo simulation. We found that: (1) according to the SPA evaluation results, areas of extremely serious pollution were distributed downstream of the tailings and spoil bank. The groundwater in the study area was mainly affected by the tailings reservoir leakage and the spoil bank leachate. (2) Based on the uncertainty analysis, the serious pollution risks for observation wells 1, 2, 3, 4, 5, 6 and 7 were 100%, 100%, 64%, 79%, 52%, 100% and 23%, respectively. Groundwater in the southeast and northwest of the study area had a higher risk of pollution. In addition, pollution risk in the area near the spoil bank and tailings was higher than that of other areas. (3) The surrogate model established using the Kriging method not only had high accuracy and could fully approximate the input–output relationships of the simulation model, but also significantly reduced computing load and computation time. The results can provide a scientific basis for the prevention and control of groundwater pollution.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Freeze–thaw cycles alter soil properties markedly and cause a subsequent change in soil erosion, however previous studies about freeze–thaw cycles’ influence on soil physical properties were restricted to simulating runoff and soil loss on cropping slopes in cold regions and failed to invoke responses of soils under different degraded conditions to freeze–thaw cycles. This study was designed to compare and quantify the responses of different degraded soils to freeze–thaw cycles in laboratory setting. The soil conditions were divided into five types: original profile, degraded profile, parent profile, deposited profile and compacted surface. Samples were collected from the black soil region in Northeast China and were frozen (− 12 °C for 12 h) and then thawed (8 °C for 12 h) for certain times. Samples without freeze–thaw cycles were treated as control group. Porosity, aggregate mean weight diameter, saturated hydraulic conductivity and water retention curves were tested for control and experimental samples. Results showed that porosity and saturated hydraulic conductivity significantly increased (maximum for degraded profile), while mean weight diameter decreased (maximum for compacted surface) compared with control group. After 30 freeze–thaw cycles, remaining water contents increased in deposited and original profiles, while decreased in compacted surface. Generally, well-structured soils are more difficult to be broken by repeated FTCs. The first freeze–thaw cycle displayed evident influence on soil physical properties under original profile, and at least one threshold of cycle time (between 5 and 20) existed. These findings may help improve understanding the functional mechanism of freeze–thaw cycles on soil erosion processes.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This paper presents an investigation on the effect of grouting into multi-bed-separation to control mining-induced surface subsidence. In the overburden without obvious thick-and-hard strata for generating large-scale bed separation, overburden grouting is carried out by increasing the number of boreholes and grouting strata. The scale model test, numerical simulation, and field measurements are used to study distribution and process of bed separation and to compare the overburden failure with surface subsidence due to pre- and post-overburden grouting, with a case study of the Qi’nan Coal Mine, Anhui Province, China. The scale model test and numerical simulation results of the overburden grouting process are in close agreement with those obtained from the field measurements. Filling masses with different diffusion radii are commonly formed in the different bed separation, which are overlaid to control the surface subsidence. It is proven that overburden grouting can successfully mitigate overburden failure and subsidence without obvious hard strata and bed separations. This provides an effective and cost-efficient approach for addressing the surface subsidence and overburden deformation problems due to mining.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Fractured carbonate gas reservoirs feature high heterogeneity and difficulty in development, and the invasion of edge and bottom water intensifies the complexity of exploitation of such gas reservoirs. In this study, reservoir cores with a permeability of 0.001 mD, 0.1 mD, and 10 mD were selected by analyzing the fracture characteristics of the Longwangmiao gas reservoir, and water invasion in fractured carbonate gas reservoirs with edge and bottom water was simulated using an experimental system to investigate the effects of different parameters on gas reservoir exploitation. The results show that the larger the water volume ratio, the more serious the water invasion and the lower the recovery factor. But water aquifer did not strongly affect the recovery factor once the water aquifer exceeded a critical value. The higher the gas production rate, the faster the water invasion and the smaller the recovery factor. The recovery factor peaked when the gas production rate was equivalent to the gas supply capacity of the matrix to the fractures. For gas reservoirs with the overall permeability, the higher the matrix permeability, the higher the recovery factor. Although an appropriate fracturing scale was able to enhance the recovery factor when its matrix permeability was low, an excessive fracturing scale would cause water to flow along the fractures at a rapid rate, which further caused a sharp decline in the recovery factor. With the increase of matrix permeability, fractures exerted a decreasing effect on gas reservoirs. These results can provide insights into a better understanding of water invasion and the effects of reservoir properties so as to optimize gas production in fractured carbonate gas reservoirs.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Groundwater samples were collected from 105 wells in the Jiroft aquifer in southeastern Iran in 2017 to assess the suitability of the groundwater for potable use using water quality indices including the Canadian Council of Ministers of the Environment water quality index (CCMEWQI) and the modified drinking water quality index (MDWQI). Groundwater quality was also assessed by a number of statistical methods and the use of piper diagrams. The assessment of the groundwater quality using the CCMEWQI indicated that 79% of the groundwater samples fell in the “excellent” class for drinking usage. The results of the assessment with the MDWQI indicated that all samples could be categorized as having an “excellent” quality for potable use. An assessment of the groundwater data with principal component analysis produced two principal components that accounted for 86.88% of the variance of the data. Factor 1 had strong positive loadings for Na〈sup〉+〈/sup〉, Ca〈sup〉2+〈/sup〉, Cl〈sup〉−〈/sup〉, SO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉, TH and TDS. This factor is likely to be linked to the combined effects of aquifer mineral–groundwater reactions and the result of evaporative concentration. Factor 2 had a strong positive loading for HCO〈sub〉3〈/sub〉〈sup〉−〈/sup〉. HCO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 is likely to have originated from carbonate dissolution and the microbial respiration of organic carbon in the soil profile. About of 80% of the water wells that were categorized in cluster 1 were found to be suitable for drinking water usage. A piper diagram indicated that Ca〈sup〉2+〈/sup〉, Na〈sup〉+〈/sup〉, HCO〈sub〉3〈/sub〉〈sup〉−〈/sup〉+CO〈sub〉3〈/sub〉〈sup〉2−〈/sup〉 and SO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉 were the dominant ions in samples that were categorized as belonging to cluster 1. In cluster 2, Na〈sup〉+〈/sup〉, SO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉 and Cl〈sup〉−〈/sup〉 were the dominant ions.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The water-blocking property of clay at the bottom of the Cenozoic overburden is an important factor for mining safety and protecting underground latent water resources in thin bedrock coal seam mining. The failure mechanism of such a clay is studied based on the actual engineering background of the SanYuan Coal Mine. The failure of the overlying clay layer is due to the reduction in the supporting space of the clay layer with the progression of coal mining, and the overlying clay layer will subside due to the self-weight load. Therefore, the vertical stress, horizontal stress and shear stress of the soil change during subsidence, and the change in these stresses determine whether the clay layer fails. Then, the failure criterion of soil expressed by the vertical stress, horizontal stress and shear stress is derived based on Mohr–Coulomb shear failure theory. Next, the function relating the stress and subsidence magnitudes are established by fit analysis. Finally, a failure criterion expressed in terms of soil subsidence amount is presented. Based on the failure criterion expressed by soil subsidence amount, a method for soil failure discriminant is proposed, in which only the subsidence amount is necessary to judge the soil failure state. This method is applied to the engineering of the SanYuan Coal Mine to get the failure subsidence amount curve of clay layer I. The results show that the failure subsidence amount curve plots below the subsidence amount curves of clay layer I at any advancing distance; that is, the clay layer did not fail. An investigation of the source and amount of water inflow to the 3301 working face also verifies that the clay layer does not fail, and the failure discriminant method used to judge the failure state of the soil is appropriate and convenient for use in engineering applications.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉To understand the characteristics such as the pollutants and the sources of heavy metals in the Hunchun basin farmland soil, soil samples were collected and the contents of As, Hg, Cu, Pb, Zn, Cr, Ni, and Cd were measured. The enrichment factor (EF) was calculated. Multiple statistical analyses including correlation analysis and principal component analysis was executed. The results show that the mean contents of As Hg, Cu, Pb, Zn, Cr, Ni, and Cd were 9.09 mg kg〈sup〉−1〈/sup〉, 0.06 mg kg〈sup〉−1〈/sup〉, 20.17 mg kg〈sup〉−1〈/sup〉, 23.34 mg kg〈sup〉−1〈/sup〉, 68.25 mg kg〈sup〉−1〈/sup〉, 65.02 mg kg〈sup〉−1〈/sup〉, 22.91 mg kg〈sup〉−1〈/sup〉, and 0.12 mg kg〈sup〉−1〈/sup〉, respectively in the Hunchun basin. The values of the mean content were not above the criterion of the China Standard of Soil Environmental Quality (GB15618-1995, CSSEQ). The contents of Pb and Zn were lower than the background values of Jilin province. However, the contents of the other heavy metals exceeded the background values, particularly for Hg. More than 20% of the samples were significantly polluted by Hg, according to the EF, and less than 10% by other elements. The main sources of mercury in the Hunchun basin are artificial activity such as the lighting of coal fires by power stations and loose residents, dusts arising from coal transport, pesticides, and fertilizers. The other heavy metals reach along with the parent material in the whole area. However, in the high enrichment area, the sources of Cu, Zn, and Cd were farming, communications, and transportation; the sources of As are sewage irrigation, pesticides, and fertilizers; the sources of Pb are communication and transportation; the sources of Cr are dusts from the mining, transport, and burning of coal.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In order to understand the interaction between groundwater, surface water and sediments, there is a need for speciation analysis of trace elements in the mentioned matrices. This could be done experimentally or by calculation with e.g. thermodynamic codes. This article will give a short overview of methods with some examples and results. Speciation in water could be determined by thermodynamic calculations with e.g. PHREEQC or Visual MINTEQ. Experimental speciation in water could be done by ultrafiltration or dialysis in situ. If applicable, in situ dialysis in the field is simple with little need of equipment. Speciation of trace elements in drinking water is of special interest to assess possible health effects. Speciation of trace elements in sediments and soils can be done by any one of the numerous selective extractions. Which speciation approach depends on which trace elements are of interest. A common need is to get information about plant uptake of specific elements.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In mining areas, fresh groundwater plays an essential role in meeting the water needs for coal production, agriculture, animal husbandry, and human consumption. The objective of this study is to obtain a deeper understanding of the groundwater evolution processes, and to assess the groundwater quality and its suitability for domestic and irrigation purposes in Chenqi coalfield, located in the Hulunbuir grassland of Inner Mongolia, China. 21 groundwater samples were collected from three different landforms (high plain, plain, and river valley) for major ions and trace metals analyses. General hydrochemistry, correlation, and hierarchical cluster analysis methods were employed. The results show that the groundwater is predominantly of the HCO〈sub〉3〈/sub〉–Na·Ca type and HCO〈sub〉3〈/sub〉–Ca·Na in the plain and river valley areas, and of the Cl·(HCO〈sub〉3〈/sub〉·SO〈sub〉4〈/sub〉)–Na·Ca in the high plain area. The groundwater circulation is regulated by natural processes: in the plain and river valley areas, rock weathering, dissolution of silicates (especially plagioclase), and reverse cation exchange are the major hydrogeochemical processes occurring, whereas, in the high plain area, evaporation and dissolution of halite, silicates, and gypsum are the main hydrogeochemical processes. Besides, mining activities have a certain impact on groundwater quality due to the change of groundwater circulation conditions. Groundwater in the plain and river valley areas is suitable for drinking and irrigation purposes, with low concentrations of all parameters. However, in the high plain area, total hardness (TH), high total dissolved solids (TDS), and Cl〈sup〉−〈/sup〉 and SO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉 concentrations limit the suitability of the groundwater for drinking purposes, while high EC and Na concentration makes it unsuitable for irrigation. These results aid in sustainable management of water resources in the study area, and provide a reference for the sustainable utilization of water resources and the rational exploitation of natural resources in other coal mining areas of the world.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The Zagros Mountains are one of the key water sources for Iran and recession of the snow line would have an impact on regional water resources. In this study, we used Moderate Resolution Imaging Spectro radiometer (MODIS) data obtained from 2000 to 2016 to investigate the upward retreat of the Temporary Snow Line Elevation (TSLE) for the months with the greatest snowfall and highest snow lines (December, January, and February) in the Oshtorankooh region. In addition, to gain a better insight into the impact of recent climate change on the snow cover in Oshtorankooh and its TSLE variations, the Mann–Kendall and TSA non-parametric tests were used for the time period 2000–2016. The results showed an upward retreat of the TSLE. The ground surface temperature observations analyzed using the MODIS data show a temperature increase of 0.52–0.99 °C (Aqua MODIS) and 0.82–1.12 °C (Terra MODIS) in the same time period. According to the Mann–Kendall and TSA methods, climatic parameters have changed during recent years in most of the studied stations and climate change is responsible for Oshtorankooh TSLE variation, so that the TSLE during the studied statistical period demonstrated an upward movement in four orientations (North, South, East, West).The largest variation between December and the other months (January and February) was observed between 2004 and 2016 247.18 km〈sup〉2〈/sup〉, 76.05 km〈sup〉2〈/sup〉, and 249.64 km〈sup〉2〈/sup〉, respectively.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This study presents a novel ensemble group method of data handling (EGMDH) model based on classification for the prediction of liquefaction potential of soils. Liquefaction is one of the most complex problems in geotechnical earthquake engineering. The database used in this study consists of 212 CPT-based field records from eight major earthquakes. The input parameters are selected as cone tip resistance, total and effective stress, penetration depth, max peak horizontal acceleration and earthquake magnitude for the prediction models. The proposed EGMDH model results were also compared to the other classifier models, particularly the results of the group method of data handling (GMDH) model. The results of this study indicated that the proposed EGMDH model has achieved more successful results on the prediction of the liquefaction potential of soils compared to the other classifier models by improving the prediction performance of the GMDH model.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The study was conducted with an aim to provide practical solution for the groundwater management in three villages namely Singhola, Ghoga and Dhirpur of the North-West Delhi, India. LANDSAT remote-sensing datasets for the last four decades (1977–2018) were assessed to determine changes in vegetation cover at the selected sites. The Google Earth Engine was used to determine how values of the Normalized Difference Vegetation Index (NDVI) were found to have varied spatially and over time for the selected sites. Strong correlations were found between the NDVI values of surface features including waterbodies, forest land, agricultural land and urban areas in Singhola, Ghoga and Dhirpur, respectively. The relative infiltration capacity of soils was highest (92.9%) and lowest (57%) for Singhola and Dhirpur, respectively, due to spatial differences in soil texture. In each village, locations exhibiting a higher soil infiltration capacity could be used for implementing managed aquifer recharge schemes using rainwater harvested from rooftops in the villages. This assessment indicated that the village of Ghoga has the highest potential (3,76,98,013.08 m〈sup〉3〈/sup〉) for aquifer recharge through rooftop rainwater harvesting as compared to the other two villages.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The unified strength theory is one of the most suitable theories to study the influence of the intermediate principle stress, of which the influence could be considered using a parameter 〈em〉b〈/em〉. A physical model experiment and numerical simulation were conducted to comparatively study such influences for a loess foundation supporting a strip footing, and the proper value of 〈em〉b〈/em〉 for the foundation was determined. The value of 〈em〉b〈/em〉 has a significant influence on the calculation of the stress distribution, bearing capacity, and failure characteristics of the foundation. The calculated bearing capacity increased linearly with increasing 〈em〉b〈/em〉, and an improvement factor of 60–100% could be obtained by using 〈em〉b 〈/em〉= 1.0 over using 〈em〉b 〈/em〉= 0.0. Based on the comparison, the authors found that 〈em〉b 〈/em〉= 0.17–0.20 resulted in a valid fit for the studied loess foundation, which provided an improvement in the bearing capacity of 15–18% over what was calculated using the Mohr–Coulomb failure law.〈/p〉