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  • Articles  (162)
  • De Gruyter  (162)
  • 2010-2014  (162)
  • Natural Sciences in General  (162)
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  • Articles  (162)
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  • 1
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    Biohydrology research after Landau 2013 conference (2014)
    De Gruyter
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    Publication Date: 2014-12-01
    Electronic ISSN: 0042-790X
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Natural Sciences in General
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  • 2
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    Tensile and erosive strength of soil macro-aggregates from soils under different management system (2014)
    De Gruyter
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    Publication Date: 2014-12-01
    Description: Reduced soil tillage practices are claimed to improve soil health, fertility and productivity through improved soil structure and higher soil organic matter contents. This study compares soil structure stability of soil aggregates under three different tillage practices: conventional, reduced and no tillage. The erosive strength of soil aggregates has been determined using the abrasion technique with the soil aggregate erosion chambers (SAE). During abrasion soil aggregates have been separated into the exterior, transitional and interior regions. The forces needed to remove the material from the aggregate were calculated as erosive strength and compared with the tensile strength of the aggregates derived from crushing tests. The relationship between aggregate strength and other soil properties such as organic carbon and hydrophobic groups’ content has also been identified. The results show that erosive and tensile strength of soil aggregates is very low in topsoil under conventional and reduced tillage comparing with the subsoil horizons. Negative correlation was found between the content of organic carbon, hydrophobic compounds and erosive aggregate strength which suggests that the stabilising effect of soils organic carbon may be lost with drying. The positive relationship between the tensile strength and erosive strength for aggregates of 8-5 mm size suggests that the total strength of these aggregates is controlled by the sum of strength of all concentric layers
    Electronic ISSN: 0042-790X
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Natural Sciences in General
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  • 3
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    Sink plot for runoff measurements on semi-flat terrains: preliminary data and their potential hydrological and ecological implications (2014)
    De Gruyter
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    Publication Date: 2014-12-01
    Description: In arid and semiarid regions where water is the main limiting factor, water redistribution is regarded as an important hydrological process of great ecological value. By providing additional water to certain loci, moist pockets of great productivity are formed, characterized by high plant biomass and biological activity. These moist pockets are often a result of runon. Yet, although runoff may take place on semi-flat undulating surfaces, runoff measurements are thus far confined to slopes, where a sufficient gradient facilitates downslope water harvesting. On undulating surfaces of mounds and depressions, such as in interdunes, no quantification of the amount of water reaching depressions is feasible due to the fact that no reliable method for measuring the runoff amounts in semi-flat terrains is available. The current paper describes specific runoff plots, designed to measure runoff in depressions (sinks). These plots, termed sink plots (SPs), were operative in the Hallamish dunefield (Negev Desert, Israel). The paper presents measurements of runoff yield that were carried out between January 2013 and January 2014 on SPs and compared them to runoff obtained from crusted slope plots and fine-grained (playa) surfaces. The potential hydrological and ecological implications of water redistribution within semi-flat terrains for this and other arid ecosystems are discussed.
    Electronic ISSN: 0042-790X
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Natural Sciences in General
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  • 4
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    Effects of patterned Artemisia capillaris on overland flow resistance under varied rainfall intensities in the Loess Plateau of China (2014)
    De Gruyter
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    Publication Date: 2014-12-01
    Description: In this paper simulated rainfall experiments in laboratory were conducted to quantify the effects oƒ patchy distributed Artemisia capillaris on spatial and temporal variations oƒ the Darcy-Weisbach friction coefficient (f). Different intensities oƒ 60, 90, 120, and 150 mm h-1 were applied on a bare plot (CK) and four different patched patterns: a checkerboard pattern (CP), a banded pattern perpendicular to slope direction (BP), a single long strip parallel to slope direction (LP), and a pattern with small patches distributed like the letter ‘X’ (XP). Each plot underwent two sets oƒ experiments, intact plant and root plots (the above-ground parts were removed). Results showed that mean ƒ for A. capillaris patterned treatments was 1.25-13.0 times oƒ that for CK. BP, CP, and XP performed more effectively than LP in increasing hydraulic roughness. The removal oƒ grass shoots significantly reduced f. A negative relationship was found between mean ƒ for the bare plot and rainfall intensity, whereas for grass patterned plots fr (mean ƒ in patterned plots divided by that for CK) increased exponentially with rainfall intensity. The ƒ -Re relation was best fitted by a power function. Soil erosion rate can be well described using ƒ by a power-law relationship
    Electronic ISSN: 0042-790X
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Natural Sciences in General
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  • 5
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    Computational investigation of liquid-solid slurry flow through an expansion in a rectangular duct (2014)
    De Gruyter
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    Publication Date: 2014-09-01
    Description: The flow of a mixture of liquid and solid particles at medium and high volume fraction through an expansion in a rectangular duct is considered. In order to improve the modelling of the phenomenon with respect to a previous investigation (Messa and Malavasi, 2013), use is made of a two-fluid model specifically derived for dense flows that we developed and implemented in the PHOENICS code via user-defined subroutines. Due to the lack of experimental data, the two-fluid model was validated in the horizontal pipe case, reporting good agreement with measurements from different authors for fully-suspended flows. A 3D system is simulated in order to account for the effect of side walls. A wider range of the parameters characterizing the mixture (particle size, particle density, and delivered solid volume fraction) is considered. A parametric analysis is performed to investigate the role played by the key physical mechanisms on the development of the two-phase flow for different compositions of the mixture. The main focuses are the distribution of the particles in the system and the pressure recovery
    Electronic ISSN: 0042-790X
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Natural Sciences in General
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  • 6
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    The joint probability distribution of runoff and sediment and its change characteristics with multi-time scales (2014)
    De Gruyter
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    Publication Date: 2014-09-01
    Description: River runoff and sediment transport are two related random hydrologic variables. The traditional statistical analysis method usually requires those two variables to be linearly correlated, and also have an identical marginal distribution. Therefore, it is difficult to know exactly the characteristics of the runoff and sediment in reality. For this reason, copulas are applied to construct the joint probability distribution of runoff and sediment in this article. The risk of synchronous-asynchronous encounter probability of annual rich-poor runoff and sediment is also studied. At last, the characteristics of annual runoff and sediment with multi-time scales in its joint probability distribution space are simulated by empirical mode decomposition method. The results show that the copula function can simulate the joint probability distribution of runoff and sediment of Huaxia hydrological station in Weihe River well, and that such joint probability distribution has very complex change characteristics at time scales.
    Electronic ISSN: 0042-790X
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Natural Sciences in General
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  • 7
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    Application of a technique for scenario prediction of climate change impact on the water balance components of northern river basins (2014)
    De Gruyter
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    Publication Date: 2014-09-01
    Description: The scenario forecasting technique for assessing changes of water balance components of the northern river basins due to possible climate change was developed. Three IPCC global emission scenarios corresponding to different possible scenarios for economic, technological, political and demographic development of the human civilization in the 21st century were chosen for generating climate change projections by an ensemble of 16 General Circulation Models with a high spatial resolution. The projections representing increments of monthly values of meteorological characteristics were used for creating 3-hour meteorological time series up to 2063 for the Northern Dvina River basin, which belongs to the pan-Arctic basin and locates at the north of the European part of Russia. The obtained time series were applied as forcing data to drive the land surface model SWAP to simulate possible changes in the water balance components due to different scenarios of climate change for the Northern Dvina River basin
    Electronic ISSN: 0042-790X
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Natural Sciences in General
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  • 8
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    Modelling soil water content variations under drought stress on soil column cropped with winter wheat (2014)
    De Gruyter
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    Publication Date: 2014-12-01
    Description: Mathematical models are effective tools for evaluating the impact of predicted climate change on agricultural production, but it is difficult to test their applicability to future weather conditions. We applied the SWAP model to assess its applicability to climate conditions, differing from those, for which the model was developed. We used a database obtained from a winter wheat drought stress experiment. Winter wheat was grown in six soil columns, three having optimal water supply (NS), while three were kept under drought-stressed conditions (S). The SWAP model was successfully calibrated against measured values of potential evapotranspiration (PET), potential evaporation (PE) and total amount of water (TSW) in the soil columns. The Nash-Sutcliffe model efficiency coefficient (N-S) for TWS for the stressed columns was 0.92. For the NS treatment, we applied temporally variable soil hydraulic properties because of soil consolidation caused by regular irrigation. This approach improved the N-S values for the wetting-drying cycle from -1.77 to 0.54. We concluded that the model could be used for assessing the effects of climate change on soil water regime. Our results indicate that soil water balance studies should put more focus on the time variability of structuredependent soil properties.
    Electronic ISSN: 0042-790X
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Natural Sciences in General
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  • 9
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    Transpiration and biomass production of the bioenergy crop Giant Knotweed Igniscum under various supplies of water and nutrients (2014)
    De Gruyter
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    Publication Date: 2014-12-01
    Description: Soil water availability, nutrient supply and climatic conditions are key factors for plant production. For a sustainable integration of bioenergy plants into agricultural systems, detailed studies on their water uses and growth performances are needed. The new bioenergy plant Igniscum Candy is a cultivar of the Sakhalin Knotweed (Fallopia sachalinensis), which is characterized by a high annual biomass production. For the determination of transpiration-yield relations at the whole plant level we used wicked lysimeters at multiple irrigation levels associated with the soil water availability (25, 35, 70, 100%) and nitrogen fertilization (0, 50, 100, 150 kg N ha-1). Leaf transpiration and net photosynthesis were determined with a portable minicuvette system. The maximum mean transpiration rate was 10.6 mmol m-2 s-1 for well-watered plants, while the mean net photosynthesis was 9.1 μmol m-2 s-1. The cumulative transpiration of the plants during the growing seasons varied between 49 l (drought stressed) and 141 l (well-watered) per plant. The calculated transpiration coefficient for Fallopia over all of the treatments applied was 485.6 l kg-1. The transpiration-yield relation of Igniscum is comparable to rye and barley. Its growth performance making Fallopia a potentially good second generation bioenergy crop.
    Electronic ISSN: 0042-790X
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Natural Sciences in General
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  • 10
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    An automated microinfiltrometer to measure small-scale soil water infiltration properties (2014)
    De Gruyter
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    Publication Date: 2014-09-01
    Description: We developed an automated miniature constant-head tension infiltrometer that measures very small infiltration rates at millimetre resolution with minimal demands on the operator. The infiltrometer is made of 2.9 mm internal radius glass tube, with an integrated bubbling tower to maintain constant negative head and a porous mesh tip to avoid air-entry. In the bubbling tower, bubble formation and release changes the electrical resistance between two electrodes at the air-inlet. Tests were conducted on repacked sieved sands, sandy loam soil and clay loam soil, packed to a soil bulk density ρd of 1200 kg m-3 or 1400 kg m-3 and tested either air-dried or at a water potential ψ of -50 kPa. The change in water volume in the infiltrometer had a linear relationship with the number of bubbles, allowing bubble rate to be converted to infiltration rate. Sorptivity measured with the infiltrometer was similar between replicates and showed expected differences from soil texture and ρd, varying from 0.15 ± 0.01 (s.e.) mm s-1/2 for 1400 kg m-3 clay loam at ψ = -50 kPa to 0.65 ± 0.06 mm s-1/2 for 1200 kg m-3 air dry sandy loam soil. An array of infiltrometers is currently being developed so many measurements can be taken simultaneously.
    Electronic ISSN: 0042-790X
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Natural Sciences in General
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