ALBERT

Description: Few studies have focused on the relationship between the various causes of groundwater level fluctuations and the seawater intrusion process, due to the complexity of this relationship, being the aim of this paper. Piezometric fluctuations in coastal aquifers are determined by a number of processes and their characterization depends on the complexity of the aquifer stratigraphy, as well as many other hydrodynamic factors. The precipitation regime, tides, wave setup and storm surges, as well as atmospheric pressure are the most relevant of these processes. By means of a series of observations made at an experimental site in south-eastern Spain, this study demonstrates the complexity of water table fluctuations in coastal zones. The study employed two piezometers situated very close to the shoreline, excavated in detritic deposits with highly variable hydraulic conductivity (semi-confined aquifer). Continuous measurements were taken of hydraulic head, tide height, electrical conductivity and water temperature. The study concludes that precipitation has the greatest effect on piezometric level, followed by atmospheric pressure and wave action, while the semi-diurnal and fortnightly tidal cycles caused variations of smaller amplitude in the piezometric logs. All these oscillations affect the position of the fresh water-seawater interface. The attenuation of the tidal amplitude observed at the two monitoring points was lower than the value calculated using analytical solutions, and this is due to the semi-confined nature of the aquifer. The calculated tidal efficiency is around 0.4-0.5, giving a t lag of about 3 h, with a 10–15 min delay between monitoring boreholes, P-II and PI. We also identified that the response of water conductivity and temperature to tidal cycles is not synchronized with the variations in the piezometric level influenced by tidal fluctuations.

Description: The authors propose a measurement method that divides the depth of the soil sample in discrete regions to investigate soil water propagation dynamics using soil impedance measurements. Experiments were conducted on a cylindrical phantom using a clay loam soil sample (60 % clay, 21 % loam and 19 % sand). The resulting impedance changes represent the wetting front (WF) propagation process at the different measurement depths. The measured impedance data is used to A) show graphically the wetting front propagation process, obtain B) a 1st order model, C) an ARX1821 model of the impedance change as a function of the irrigation volume applied and D) estimating changes in water content using a neural network. The results indicate that the proposed measurement technique can be used to detect and predict the movement of liquid trough the soil sample. The neural network permits inferring the water content from impedance and soil-water mixture temperature values. Changes in soil impedance in each segment, due to the water propagating downwards through the soil sample, can be used to study the dynamics of the wetting front, irrigation scheduling and model improvement from physical data.

Description: The paper presents an approach to the modelling of watercourses or their sections according to and in order to determine their suitability for hydropower water use on a large scale. The method is based on a multi-criteria analysis approach which in addition to existing guidelines defines and describes in detail the main stages for model establishment and hydropower suitability analysis. Since hydropower planning stands in direct conflict with other ecological water-related objectives, evaluation of suitability is based on two main criteria, which are supported with the belonging criteria. The first main criterion is based on evaluation of watercourses by their attractiveness for hydropower water use; the second one on evaluation of watercourses according to their ecological state or value. To support proper determination of unknown model parameters (e.g. weights of selected criteria) the paper also presents an upgrade of general multi-criteria analysis process with a calibration stage, which can efficiently upgrade in cases when calibration data is available. The proposed method was tested and discussed on a real case study with three dislocated Slovenian Alpine watercourses, where weights of preselected criteria and some thresholds of performance functions were selected as model variables and calibrated.

Description: Various scientific and technological based solutions such as virtual water trading, desalination, groundwater extraction and wastewater reuse have been proposed and implemented in many parts of Asia and Africa to relieve water scarcity. This paper applies SWOT (strengths, weaknesses, opportunities and threats) analysis to examine the suitability of these alternative water solutions to alleviate water scarcity. SWOT analysis proves to be a useful decision making tool as it provides a qualitative approach to simplify multilayer and interdisciplinary problems. The main input for the SWOT analysis consists of knowledge gathered from seven experts in the field of water and environmental sciences. The results show that compared to other solutions, wastewater reuse offers the most desirable qualities as a viable water solution for sustainable water management in Asia and Africa.

Description: Groundwater withdrawals can reduce aquifer-to-stream flow and induce stream-to-aquifer flow. These effects involve potential threats over surface water and groundwater quantity and quality. As a result, the description of stream-aquifer flow in space and time is of high interest for water managers. In this study, the EauDyssée platform, an integrated groundwater/surface water model is extended to provide the distribution of stream-aquifer flow at the regional scale. The methodology is implemented over long periods (17 years) in the Seine river basin (76 375 km 2 , France) with a 6 481 km long simulated river network. The study scale is compatible with the scale of interest of water authorities, which is often larger than study scales of research projects. Net and gross stream-aquifer exchange flow are computed at the daily time step over the whole river network at a resolution of 1 km. Simulation results highlight that a major proportion of the main stream network (82 %) is supplied by groundwater. Groundwater withdrawals induce a reduction of net aquifer-to-stream flow (−19 %) at the basin scale and flow reversals in the vicinity of pumping locations. Such an integrated model provided at the appropriate regional scale is an essential tool provided to water managers for the implementation of the EU Water Framework Directive.

Description: This paper presents the comparison of two hybrid methodologies for the two-objective (cost and resilience) design of water distribution systems. The first method is a low-level hybrid algorithm (LLHA), in which a main controller (the non-dominated sorting genetic algorithm II, NSGA-II) coordinates various subordinate algorithms. The second method is a high-level hybrid algorithm (HLHA), in which various sub-algorithms collaborate in parallel. Applications to four case studies of increasing complexity enable the performances of the hybrid algorithms to be compared with each other and with the performance of the NSGA-II. In the case study featuring low/intermediate complexity, the hybrid algorithms (especially the HLHA) successfully capture a more diversified Pareto front, although the NSGA-II shows the best convergence. When network complexity increases, instead, the hybrid algorithms (especially the LLHA) turn out to be superior in terms of both convergence and diversity. With respect to both the HLHA and the NSGA-II, the LLHA is capable of detecting the final front in a single run with a lower computation burden. In contrast, the HLHA and the NSGA-II, which are more affected by the initial random seed, require numerous runs with an attempt to reach the definitive Pareto front. On the other hand, a drawback of the LLHA lies in its reduced ability to deal with general problem formulations, i.e., those not relating to water distribution optimal design.

Description: Intensification of heavy precipitation as discussed in climate change studies has become a public concern, but it has not yet been examined well with observed data, particularly with data at short temporal scale like hourly and sub-hourly data. The original data set was retrieved by using an automated recovery approach. We chose four stations, namely, Vercelli (since 1927), Bra (since 1933), Lombriasco (since 1939) and Pallanza (since 1950) which are located in the northwest of Italy. We assessed trends for durations from 5 min to 12 h in seasonal, annual maxima, and number and magnitude of exceedances of the 95th percentile. Split sample tests have been undertaken to assess differences in quantile estimates derived using a Generalised Pareto distribution fitted to Peaks-Over-Threshold series. The statistical analyses performed include parametric and non-parametric tests. Mostly, we cannot reject the trend stationarity hypothesis. There is no uniform trend on extreme events in the whole area. However, some trends are evident and significant for specific stations and specific indices. Specifically, it is obvious that extreme rainfall events have risen in the last 20 years only for short durations.

Description: A novel quantitative risk assessment for residential properties at risk of pluvial flooding in Eindhoven, The Netherlands, is presented. A hydraulic model belonging to Eindhoven was forced with low return period rainfall events (2, 5 and 10-year design rainfalls). Three scenarios were analysed for each event: a baseline and two risk-reduction scenarios. GIS analysis identified areas where risk-reduction measures had the greatest impact. Financial loss calculations were carried out using fixed-threshold and probabilistic approaches. Under fixed-threshold assessment, per-event Expected Annual Damage (EAD) reached €38.2 m, with reductions of up to €454,000 resulting from risk-reduction measures. Present costs of flooding reach €1.43bn when calculated over a 50-year period. All net-present value figures for the risk-reduction measures are negative. Probabilistic assessment yielded EAD values up to more than double those of the fixed-threshold analysis which suggested positive net-present value. To the best of our knowledge, the probabilistic method based on the distribution of doorstep heights has never before been introduced for pluvial flood risk assessment. Although this work suggests poor net-present value of risk-reduction measures, indirect impacts of flooding, damage to infrastructure and the potential impacts of climate change were omitted. This work represents a useful first step in helping Eindhoven prepare for future pluvial flooding. The analysis is based on software and tools already available at the municipality, eliminating the need for software upgrading or training. The approach is generally applicable to similar cities.

Description: The use of inverse modeling techniques has greatly increased during the past several years because the advances in numerical modeling and increased computing power. Most of these methods require an a priori definition of the stochastic structure of conductivity ( K ) fields that is inferred only from K measurements. Therefore, the additional conditioning data, that implicitly integrate information not captured by K data, might lead to changes in the a priori model. Different inverse methods allow different degrees of structure adaptation to the whole set of data during the conditioning procedure. This paper illustrates the application of a powerful stochastic inverse method, the Gradual Conditioning (GC) method, to two different sets of data, both non-multiGaussian. One is based on a 2D synthetic aquifer and another on a real-complex case study, the Macrodispersion Experiment (MADE-2), site on Columbus Air Force Base in Mississippi (USA). We have analyzed how additional data change the a priori model on account of the perturbations performed when constraining stochastic simulations to data. Results show how the GC method tends to honour the a priori model in the synthetic case, showing fluctuations around it for the different simulated fields. However, in the 3D real case study, it is shown how the a priori structure is slightly modified not obeying just to fluctuations but possibly to the effect of the additional information on K, implicit in piezometric and concentration data. We conclude that implementing inversion methods able to yield a posteriori structure that incorporate more data might be of great importance in real cases in order to reduce uncertainty and to deal with risk assessment projects.

Description: Desalination has proven to be a reliable and efficient water supply option in many countries, especially in times of water scarcity. However, high desalination costs and high prices for desalinated water (twice or three times higher than those from traditional water sources) have been hindering an uptake and the development of desalination in many countries. Applied desalination technology, capital and operational costs, production capacity, water salinity are just a few factors determining the final cost of desalinated water that varies considerably between $1.7–9.5/kgal ($0.45–2.51/m 3 ). The final prices for desalinated water and the related costs for local municipalities are among the most crucial determinants of the overall short- and long-term effectiveness of desalination processes. This paper provides an in-depth analysis on economics of desalination with country specific examples. It depicts a comprehensive picture of cost variability of desalinated water and points out challenges for cost-effective desalination in the future.

Description: Drought situations can have significant impacts, affecting large areas and imposing relevant restrictions on multiple economic activities. The severity of those impacts is, normally, assessed through meteorological, agricultural and/or hydrological indices or even through estimation of water deficits or reduction of production yields (for agriculture). However, those assessments usually do not represent the socioeconomic importance of the impacts and the results are not comparable for different types of impacts or distinct regions. In this context, the present work enunciates the main principles to be considered and a methodological approach for socioeconomic evaluation of drought effects, regarding the main supply and demand characteristics of a region (water sources and associated uses), and the hydrological interlinked effects of drought situations. Moreover it describes the methodology process application to Portuguese reality and existing data as the basis of drought’s severity assessment, focusing on two drought prone areas in Portugal: the Guadiana and the Ribeiras do Algarve river basin case studies. Regarding the main specificities of the referred case studies, the economic activities (and water dependent sectors) considered for this methodology were the agricultural and the urban water supply sectors. For each of those sectors, specific assessment procedures where developed in order to estimate the respective economic impacts caused by the drought situation in the area of analysis. A global assessment of the socioeconomic relevance of drought impacts in a region is ensured through comparison of the estimated total economic impacts to the region’s annual average of the Gross Domestic Product (GDP), that enabling the comparison of results for different regions of analysis. The methodology may be applicable to any region with common hydrological and water use data and was developed to be of support for drought management and application on a drought early warning system.

Description: As more and more large reservoirs been built, competitive impoundment problem of cascade reservoirs becomes a serious matter in the flood recession. Combining the impounding principle with K value discriminant method, a novel impounding strategy of cascade reservoirs is proposed for determining the impoundment sequence and opportunity of each reservoir in premise of the flood control safety. At the same time, the impounding water level control lines of different frequency runoff are drawn according to the flood routing simulation, and then the Impounding Operation Chart (IOC) is manufactured. On this basis, a model of impoundment dispatching in advance based on the IOC is developed. Then the proposed method can be obviously accelerated by using Self-adaptive Electromagnetism-like Mechanism algorithm (SEM). Compared with the original design of impounding scheme, the result indicates that the optimal scheme can improve the fill storage ratio of cascade reservoirs and ease the contradiction between supply and demand of water resources as well with guaranteeing the safety of flood control in the watershed.

Description: The ability of water managers to maintain adequate supplies in coming decades depends, in part, on future weather conditions, as climate change has the potential to alter river flows from their current values, possibly rendering them unable to meet demand. Reliable climate projections are therefore critical to predicting the future water supply for the United States, but the resolution of the global climate models (GCMs) often used for climate forecasting is too coarse to resolve the changes that can affect hydrology, and hence water supply, at regional to local scales. We therefore apply a statistical downscaling technique that involves a correction of the cumulative distribution functions of the GCM-derived temperature and precipitation for the 20th century, and the application of the same correction to 21st century GCM projections. This is done for three meteorological stations located within the Coosa River basin in northern Georgia, and is used with a surface hydrology model to calculate future river flow statistics for the upper Coosa River. Results are compared to historical Coosa River flow and to flows calculated with the original, unscaled GCM results to determine the impact of potential changes in meteorology on future flows.

Description: Applications of the Soil and Water Assessment Tool (SWAT) require a large amount of input data to perform model simulations. Consequently, uncertainty in input data tends to influence the accuracy of SWAT hydrologic and water quality outputs. It has been shown that input uncertainty can be quantified explicitly during model calibration with latent variables. In this study, latent variables were explored to examine their sensitivity to SWAT outputs and further the potential impact of input uncertainty to model predictions. Results show that the increases in the range of latent variables pose a significant influence to streamflow and ammonia predictions while the impact was less significant in sediment responses. The performance of SWAT in predicting streamflow and ammonia declined with wider ranges of latent variables. In addition, the increase in the range of latent variables did not present noticeable effect on the corresponding predictive uncertainty in sediment predictions. In this study, the calibration results did not improve significantly with the applications of wider ranges of latent variables which are different from the findings in previous research work. The use of latent variables to incorporate input uncertainty may not be the proper alternative choice in terms of generating better results and should be carefully evaluated in the implementations of complex watershed simulation models.

Description: In this study, an iterative framework for robust reclaimed wastewater allocation (IFRWA) was developed to consider multiple climate change scenarios using multi-criteria decision making (MCDM) methods. Each iteration begins with the assumption that an additional unit of water quantity is allocated to reclaimed wastewater (RWW) sites. Based on these allocation conditions, hydrologic simulations are performed and evaluated using the incremental alternative evaluation index (IAEI) to rank the best sites for each unit water quantity. The minimax regret strategy is employed to consider the uncertainty inherent in the climate change scenarios. The consequent robust ranking of the IAEIs is applied to determine the final allocation of the unit water quantity in a given iteration. This iteration continues until the total allocated water quantity satisfies the maximum available capacity of RWW for use in the studied watershed. Our results show that this incremental and robust framework can be used to determine the reasonable capacities of RWW at multiple sites within the watershed by considering various aspects of RWW use, including the water quantity and the socio-economic aspects of decision making. A choice and concentration strategy based on IAEIs should be employed to achieve the maximum utility considering the physical constraints (capacity and cost). If economic considerations, such as the cost of construction and management, are included, this framework can be applied to real problems.

Description: The problem of allocation of limited water resources for multiple and diverse activities with growing demand calls for the need to develop appropriate tools for water valorization. This work develops a methodology to estimate the economic value of water in a basin with large hydropower production and a growing demand for rice irrigation, based on a coupled hydrological and electric system modelling approach. Inflow deficits to the hydroelectric system induced by the irrigation reservoirs within the basin are simulated under different irrigation scenarios. The simulated inflow deficits are integrated to an existing model of the interconnected electric system to evaluate the associated increase in generation costs under different energy scenarios. The impact of inflow deficits in turbinated and spilled flow and generation costs are comprehensively explored. Both annual mean and interannual variability of overcosts increase with increasing irrigation demand. However, if normalized by yearly varying rice planted area, the distribution of additional costs does not change substantially. Moreover, the distribution of normalized overcosts per unit irrigated area is also invariant to energy scenarios, although the relative impact in total costs decreases as the proportion of hydroelectric generation diminishes.

Description: In this study, several hydrogeological catchments of Central Italy have been characterized focusing the attention on the presence of areas in which, over the last two decades, the hydrological equilibrium between recharge and discharge (phenomena of marked reduction of spring discharge and progressive drawdown of groundwater levels) has been compromised by overexploitation of groundwater resources. A GIS system has been used in order to develop the study and the homogenous distribution of the hydrological knowledge and of the existing imbalances has been performed. Characterizing elements of the research are: a) the definition of the hydrogeological units; b) the hydrogeological survey of around a thousand water-points; c) the monthly analysis of climatic data of numerous survey stations; d) the census and the recording of water concessions; e) the evaluation of agriculture hydro-exigency derived from the analysis of the use of soil; f) the withdrawals defined by a statistic analysis of data. These elements have allowed to define the Distributed Hydrogeological Budget which is a useful instrument to evaluate critical areas.

Description: Uneven distribution of domestic water in space and time is a major concern in many fast growing cities due to improper planning and lack of scientific approach. This problem is much severe where the maximum domestic water requirements are met from the groundwater resources. Optimising a single groundwater pumping scheme may be an easy task using simple linear programming technique but, if the number of pumping schemes and constraints are more, solutions for identifying such groundwater schemes are more difficult and laborious using conventional methods as the constraints varies in space and time. In this paper, a new technique was developed to identify new groundwater pumping schemes to meet the present and future domestic water requirements in space and time by integrating spatial optimisation technique with the groundwater model. The approach considers the possible optimum rate of groundwater pumping, minimising the cost of water supply scheme and having minimum impact on the downstream side groundwater table using high resolution satellite data (IKONOS), Geographical Information System (GIS) tools and optimisation techniques. Dehradun, which is one of the fast growing cities in India, was considered as a study area to demonstrate the proposed new technique. Domestic water demand for next two decades (up to 2,031) was forecasted and compared with the existing supplies. Nearly 48 additional groundwater pumping schemes were identified to cater the present and future demands. Its impact on the groundwater table was also studied using groundwater modelling technique.

Description: The aim of this study is to determine whether dam reoperation (the adjustment of reservoir operating rules) is an effective adaptation strategy to reduce the potential impacts of climate change and regional socio-economic developments. The Xinanjiang-Fuchunjiang reservoir cascade, located in Hangzhou Region (China), is selected as case study. We use a scenario-based approach to explore the effects of various likely degrees of water stress for the future period between 2011 and 2040, which are compared to the control period from 1971 to 2000. The scenario impacts are simulated with the WEAP water allocation model, which is interlinked with the NSGA-II metaheuristic algorithm in order to derive optimal operating rules adapted to each scenario. Reservoir performance is measured with the Shortage Index (SI) and Mean Annual Energy Production (MAEP). For the investigated scenarios, adapted operating rules on average reduce the SI with 84 % and increase the MAEP with 6.4 % (compared to the projected future performance of conventional operation). Based on the optimization results, we conclude that for the studied case dam reoperation is an effective adaptation strategy to reduce the impact of changing patterns of water supply and demand, even though it is insufficient to completely restore system performance to that of the control period.

Description: The design of a water quality monitoring network is of critical importance to watershed management. By employing both a single criterion analysis and a multiple criteria analysis, this study assessed and compared water quality monitoring designs for a river system in the Taipei Water Resource Domain (TWRD), a major water resource protected area in northern Taiwan. The case area for this work was divided into 22 sub-basins; and each sub-basin was generally based upon a river network. With a single criterion analysis, inputting different individual variables produced significantly different results. Thus, the sub-basins seen to have a greater need for a water quality monitoring system varied greatly. This study, further, observed that a multiple criteria analysis is more objective than a single criterion analysis. When considering multiple factors, this report utilized seven criteria, the top five sub-basins with a greater necessity for improved water quality monitoring records are, in order, Sub-basins 2, 5, 21, 20, and 7. This indicates that the need for a water quality monitoring system in the Sin-Dian Creek Basin and in the Bei-Shih Creek Basin is greater than that in the Nan-Shih Creek Basin. This result is a useful reference for the creation of an improved water quality management strategy in the TWRD.

Description: As one of the most important component of Non-Revenue Water (NRW), apparent loss exists in all kinds of water distribution system but hardly can be assessed due to its complexity and invisibility. Aimed to analyze the different component of apparent loss on the basis of the characteristic of flow meters in district metered areas (DMA), an effective methodology to calculate the three primary parts of NRW is presented in this paper. In particular, the real loss assessment can be carried out by Minimum Night Flow (MNF) analysis; while the unauthorized consumption can be identified by consuming variation curve; finally, the metering error is calculated by the genetic algorithm with the integrated model based on IWA water balance audit. Application of this method in water distribution network of a steel-making enterprise improves its significance in controlling NRW of DMA.

Description: River flow that is characterized by variability requires commensurate flexibility in allocating water so that water users are able to plan their activities and respond accordingly. An indicator-based assessment method is proposed in this study to evaluate the flexibility of water allocation, based on a concept that a flexible water allocation regime provides greater opportunity for users to freely decide individual water use and leads to more variability and diversity for water consumption among the users. This is demonstrated by using historical water-use data and applying the assessment method in three river basins with different water allocation regimes. These allocation regimes include the seasonal and volumetric water allocation system in the Yellow River of China, duration-based water allocation in Northwestern China, and capacity sharing in southern Queensland in the northern Murray Darling Basin of Australia. Historical water-use variability and diversity are defined and assessed. The result shows that water allocation flexibility varies across the different water entitlement regimes. Duration-based water allocation, a type of allocation that provides the highest degree of water-use autonomy, is ranked as the most flexible regime. Seasonal water allocation, which has the highest level of centralized regulation, shows the lowest flexibility. The proposed indicator based assessment method would be useful for evaluating the flexibility of policy options for water allocation. This could be helpful for improving the capability of water allocation regimes to cope with the changing environment and improving the effectiveness of water allocation systems.

Description: Complying with the objectives of the European Union Water Framework Directive, the water management organisations of Hungary and Serbia launched a common project in 2010 in order to improve the status of the channel crossing the national border. During reconstruction planning they intended to take ecological aspects into consideration. Therefore the evaluation of ecological state has been carried out for the Baja-Bezdan channel complemented by on-the-spot monitoring and biological examinations. Such a detailed survey of the channel has no precedent to date. Besides the evaluation, ecology-based proposals were phrased, which not only serve the sustainable functioning of the channel, but also help to preserve its flora and fauna.

Description: Global warming is causing important changes in climate conditions, which must be studied in detail and locally in those zones where irrigated agriculture is developed—the major consumer of water worldwide. This study proposes the climatic characterization of a historical series (1971–2000) and its future projections (2011–2099) for an Irrigation District located in the Middle Ebro Valley (Spain), for three different scenarios: low, medium, and high global emission levels of greenhouse gases. Analysis of historical series reveals a significant increase in reference evapotranspiration (3.3 mm/year 2 ; 2.4 ‰) along with a decrease in precipitation (2.5 mm/year 2 ; 5.6 ‰). A comparison was carried out between real historical data and the scenarios produced by the climate models and it was observed that the most adequate climate model to predict climate in the study zone is MPI-ECHAM5. For the XXI century, MPI-ECHAM5 predicts cyclic climate trends but with a general increment in aridity, which intensifies according to the scenario chosen. Changes in climate are affecting agriculture doubly, since evapotranspiration requirements increase at the same time that water resources decrease. These effects are felt especially in irrigated agriculture, since the growing cycles of the main crops coincide with the months most affected by climate change.

Description: As an important component of the fracturing treatment, fracturing fluids act as the carrier of proppant materials in offshore fracturing and frac-pack operations, thereby playing a decisive role in enhancing the deliverability near fractures and the productivity accordingly. According to the component analysis of seawater samples, the main challenges for developing a high temperature seawater-based fluid system were identified and the technical strategies to circumvent with these challenges were also established. To this end, novel anti-salt compound plant gum was synthetized to enhance the salt tolerance and dispersion effect of thickener. Organic boron-zirconium crosslinker was compounded to improve the crosslinking density and intensity. Chelating and screening agent, gel protective agent and temperature stabilizer were adopted to chelate metal ions, protect the gum from decomposing by organic matter or bacteria, as well as boost temperature resistance of fluid system respectively. Then a novel seawater-based fluid system was developed. The seawater-based fluid system developed has strong temperature tolerance of up to 160 °C. The performance of this fluid system was also evaluated by systematic studies. Results indicate that this new fluid system has good compatibility with formation water, without the occurrence of any precipitation during the compatibility evaluation tests. Moreover, the fluid system exhibited good leakoff control ability and a higher regained permeability than HPG solution, when the gel breaking fluid was pumped though the core samples in the targeted formation. The excellent performance of this fluid system signifies potential application prospect in the future deep-sea stimulation treatment.

Description: The data envelopment analysis (DEA) model was used to estimate the technical efficiency (TE) scores, the Malmquist total factor productivity (TFP) indices, and their implicit input shadow shares for 12 irrigation districts in Southern Alberta using data for the period 2008–12. The main purpose was to establish benchmarks so that future increases in conservation, efficiency and total factor productivity of water use (major goals of Alberta’s Water for Life strategy) can be assessed. Results of an input-oriented DEA model indicated that the irrigation districts were, on average, 84.3 % technically efficient in their input use, primarily the net water diverted. The output-oriented model indicated that the irrigation districts, alternatively, could expand their total irrigated areas by 58.3 % with the current level of input use. Over the period 2008–12, the year-to-year mean Malmquist TFP for the irrigation districts of Southern Alberta was estimated to be 0.98 %. Net water diverted was identified as the most important contributing input (76 %) to the TFP change. The second and third contributing factors were pivot irrigation technology (6 %) and precipitation (5 %).

Description: Canal section design with minimum cost, which can be considered as an objective function, involves minimization of total costs per unit length of the canal, including direct costs of per cubic meter earthworks and per meter canal lining and indirect costs of water losses through canal seepage and evaporation. Since the costs (both direct and indirect) are associated with the canal geometry and dimensions, it is possible to lower them by optimization of the mentioned objective function. For this purpose, some constraints were subjected and considered to solve the problem. Flow discharge, as the main constraint, was considered in addition to the minimum permissible velocity and Froude’s number, as subsidiary constraints. MATLAB programming software was used to demonstrate and run the optimization algorithm. The results finally were illustrated in forms of dimensionless graphs, which simplify the optimum design of canal dimensions with minimum cost per meter length. Comparing the results with other similar studies, however show the importance and role of earthworks and lining costs, as well as including the subsidiary constraints in the optimization process.

Description: The real-time availability of several satellite-based precipitation products has recently provided hydrologists with an unprecedented opportunity to improve current hydrologic prediction capability for vast river basins, particularly for ungauged regions. However, the accuracy of real-time satellite precipitation data remains uncertain. This study aims to use three widely used real-time satellite precipitation products, namely, TRMM Multi satellite Precipitation Analysis real-time precipitation product 3B42 (TMPA 3B42RT), Precipitation Estimation from Remote Sensing Information using Artificial Neural Network (PERSIAN), and NOAA/Climate Precipitation Center Morphing Technique (CMORPH), for ensemble stream flow simulation with the gridded xinanjiang (XAJ) model and shuffled complex evolution metropolis (SCEM-UA) algorithm in the middle-latitude Mishui basin in South China. To account the bias of the satellite precipitation data and consider the input uncertainty, two different methods, i.e. a precipitation error multiplier and a precipitation error model were introduced. For each precipitation input model, the posterior probability distribution of the parameters and their associated uncertainty were calibrated using the SCEM-UA algorithm, and 15,000 ensemble stream flow simulations were conducted. The simulations of the satellite precipitation data were then optimally merged using the Bayseian model averaging (BMA) method. The result shows that in Mishui basin, the three sets of real-time satellite precipitation data largely underestimated rainfall. Streamflow simulation performed poorly when the raw satellite precipitation data were taken as input and the model parameters were calibrated with gauged data. By implementing the precipitation error multiplier and the precipitation error model and then recalibrating the model, the behavior of the simulated stream flow and calculated uncertainty boundary were significantly improved. Furthermore, the BMA combination of the simulations from the three datasets resulted in a significantly better prediction with a remarkably reliable uncertainty boundary and was comparable with the simulation using the post-real-time bias-corrected research quality TMPA 3B42V7. The proposed methodology of bias adjustment, uncertainty analysis, and BMA combination collectively facilitates the application of the current three real-time satellite data to hydrological prediction and water resource management over many under-gauged basins. This research is also an investigation on the hydrological utility of multi-satellite precipitation data ensembles, which can potentially integrate additional more satellite products when the Global Precipitation Measuring mission with 9-satellite constellation is anticipated in 2014.

Description: Morse Reservoir, a major water supply for the Indianapolis metropolitan area, IN, USA, experiences nuisance cyanobacterial blooms due to agricultural and point source nutrient loadings. Hyperspectral remote sensing data from both in situ and airborne AISA measurements were applied to an adaptive model based on Genetic Algorithms-Partial Least Squares (GA-PLS) by relating the spectral signal with total nitrogen (TN) and phosphorus (TP) concentrations. Results indicate that GA-PLS relating in situ spectral reflectance to the nutrients yielded high coefficients of determination (TN: R 2  = 0.88; TP: R 2  = 0.91) between measured and estimated TN (RMSE = 0.07 mg/L; Range: 0.6–1.88 mg/L), and TP (RMSE = 0.017; Range: 0.023–0.314 mg/L). The GA-PLS model also yielded high performance with AISA imaging data, showing close correlation between measured and estimated values (TN: RMSE = 0.11 mg/L; TP: RMSE = 0.02 mg/L). An analysis of in situ data indicated that TN and TP were highly correlated with chlorophyll-a and suspended matter in the water column, setting a basis for remotely sensed estimates of TN and TP. Spatial correlation of TN, TP with chlorophyll-a and suspended matters further confirmed that remote quantification of nutrients for inland waters is based on the strong association of optically active constituents with nutrients. Based on these results, in situ and airborne hyperspectral remote sensors can provide both quantitative and qualitative information on the distribution and concentration of nutrients in Morse Reservoir. Our modeling approach combined with hyperspectral remote sensing is applicable to other productive waters, where algal blooms are triggered by nutrients.

Description: Diffuse nutrient loads are a common problem in developed and agricultural watersheds. While there has been substantial investment in best management practices (BMPs) to reduce diffuse pollution, there remains a need to better prioritize controls at the watershed scale as reflected in recent US-EPA guidance for watershed planning and Total Maximum Daily Load development. We implemented spatial optimization techniques among four diffuse source pathways in a mixed-use watershed in Northern Vermont to maximize total reduction of phosphorus loading to streams while minimizing associated costs. We found that within a capital cost range of 138 to 321 USD ha -1 a phosphorus reduction of 0.29 to 0.38 kg ha −1  year −1 , is attainable. Optimization results are substantially more cost-effective than most scenarios identified by stakeholders. The maximum diffuse phosphorus load reduction equates to 1.25 t year −1 using the most cost-effective technologies for each diffuse source at a cost of $3,464,260. However, 1.13 t year −1 could be reduced at a much lower cost of $976,417. This is the practical upper limit of achievable diffuse phosphorus reduction, above which additional spending would not result in substantially more phosphorus reduction. Watershed managers could use solutions along the resulting Pareto optimal curve to select optimal combinations of BMPs based on a water quality target or available funds. The results demonstrate the power of using spatial optimization methods to arrive at a cost-effective selection of BMPs and their distribution across a landscape.

Description: Multi-period optimization of conjunctive water management can utilize reservoirs and aquifer carry-over to alleviate drought impacts. Stakeholders’ socio-economic and environmental indices can be used to minimize the socio-economic and environmental costs associated with water shortages in drought periods. The knowledge gap here is the evaluation and inclusion of the socio-economic and environmental value of conjunctive water management in terms of its drought mitigation capability. In this paper, an integrated water quantity-quality optimization model that considers socio-economic and environmental indices is developed. The model considers and integrates reservoir and aquifer carry-over, river-aquifer interaction and water quality with stakeholders’ socio-economic indices of production, net income and labor force employment to evaluate the socio-economic and environmental value of conjunctive water management. Total dissolved solid (TDS) is used as the water quality index for environmental assessments. The model is formulated as a multi-period nonlinear optimization model, with analysis determining the optimal decisions for reservoir release and withdrawal from the river and aquifer in different months to maximize the socio-economic indices of stakeholders within the environmental constraints. The proposed model is used in Zayandehrood water resource system in Iran, which suffers from water supply and pollution problems. Model analysis results show that conjunctive water use in the Zayandehrood water basin reduces salinity by 50 % in the wetland and keeps water supply reduction during a drought under 10 % of irrigation demand.

Description: The Water Framework Directive (WFD) defines common objectives for water resources throughout the European Union (EU). Given this general approach to water preservation and water policy, the objective of this paper is to analyse whether common patterns of water consumption exist within Europe. In particular, our study uses two methods to reveal the reasons behind sectoral water use in all EU countries. The first method is based on an accounting indicator that calculates the water intensity of an economy as the sum of sectoral water intensities. The second method is a subsystem input-output model that divides total water use into different income channels within the production system. The application uses data for the years 2005 and 2009 on water consumption in the production system of the 27 countries of the EU. From our analysis it emerges that EU countries are characterized by very different patterns of water consumption. In particular water consumption by the agriculture sector is extremely high in Central/Eastern Europe, relative to the rest of Europe. In most countries, the water used by the fuel, power and water sector is consumed to satisfy domestic final demand. However, our analysis shows that for some countries exports from this sector are an important driver of water consumption. Focusing on the agricultural sector, the decomposition analysis suggests that water usage in Mediterranean countries is mainly driven by final demand for, and exports of, agricultural products. In Central/Eastern Europe domestic final demand is the main driver of water consumption, but in this region the proportion of water use driven by demand for exports is increasing over time. Given these heterogeneous water consumption patterns, our analysis suggests that Mediterranean and Central/Eastern European countries should adopt specific water policies in order to achieve efficient levels of water consumption in the European Union.

Description: The model for prediction of drought magnitudes is based on the multiplicative relationship: drought magnitude ( M ) = drought intensity ( I ) × drought duration ( L ), where I, L, and M are presumed to obey respectively the truncated normal probability distribution function (pdf), the geometric pdf, and the normal pdf. The multiplicative relationship is applied in the standardized domain of the streamflows, named as SHI (standardized hydrological index) sequences, which are treated equivalent to standard normal variates. The expected drought magnitude E( M T ), i.e. the largest value of M over a sampling period of T- time units ( T -year, T -month, and T -week) is predicted for hydrological droughts using streamflow data from Canadian prairies. By suitably amalgamating E( L T ) with mean and variance of I in the extreme number theorem based relationship, the E( M T ) is evaluated. Using Markov chain (MC), the E( L T ) is estimated involving the geometric pdf of L . The Markov chains up to order one (MC-1) were found to be adequate in the proposed model for the annual to weekly time scales. For a given level of drought probability ( q ) and a sampling period T- time units; the evaluation of E( M T ) requires only 3 parameters viz. lag-1 autocorrelation ( ρ 1 ), first order conditional probability ( q q , present instant being a drought given past instant was a drought) in SHI sequences and a parameter ø (value 0 to 1), which were estimated from historical data of streamflows. A major strength of the proposed model lies in the use of simple and widely familiar normal and geometric pdfs as its basic building blocks for the estimation of drought magnitudes.

Description: Reliability of water distribution networks (WDNs) has received much attention in recent years due to progressive aging of infrastructures and climate change. Several reliability indicators, focusing on hydraulic aspects rather than water quality, have been proposed in literature. Reliability is generally assessed resorting to well established methods coupling hydraulic simulations and stochastic techniques that describe the WDNs hydraulic performance and component availability respectively. Two main algorithms are employed to simulate WDNs: the demand driven approach (DDA) that disregards the physical relationship between actual water demand and nodal pressure, and the pressure driven approach (PDA) that explicitly incorporates it. In this paper, we show how the choice of hydraulic solver may affect reliability indicators. We modify existing quantitative indicators at nodal and network level, and define novel indicators to consider water quality aspects. These indicators are evaluated for three example WDNs; discrepancies between results obtained with the two approaches depend on network size, feeding scheme and skeletonization. Results suggest to use with caution the DDA for reliability assessment at both local and global level.

Description: Copula functions are often used for multivariate frequency analyses, but discharge and suspended sediment concentrations have not yet been modelled together with the use of 3-dimensional copula functions. One hydrological station from Slovenia and five stations from USA with watershed areas from 920 km 2 to 24,996 km 2 were used for trivariate frequency analyses of peak discharges, hydrograph volumes and suspended sediment concentrations. Different parametric marginal distributions were applied and parameters were estimated with the method of L-moments. Maximum pseudo-likelihood method was used for copula parameters estimation. With the use of statistical and graphical tests we selected the most appropriate copula model. Symmetric and asymmetric versions of Archimedean copulas were applied according to the dependence characteristics of the individual stations. We selected Gumbel-Hougaard copula as the most appropriate model for all discussed stations. Primary joint return periods OR and secondary Kendall’s return periods were calculated and comparison between selected copula functions was made. We can conclude that copula functions are useful mathematical tool, which can also be used for modelling variables that are presented in this paper.

Description: Natural climatic hazards like flood, an important hydro-geomorphic process of earth’s surface, have different regional and local impacts with significant socio-economic consequences. Similar was the case in Gujarat State, India during last week of June 2005. This study is about assessing the impact of Gujarat flood on river dynamics. It deals with extraction of water bodies information using radiance image and standard water indices i.e., Normalized Difference Water Index (NDWI) and Modified Normalized Difference Water Index (MNDWI) for pre- and post-flooding periods. Geomorphometric analysis along with drainage network extraction was done using two different Digital Elevation Models (DEMs) i.e., Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER) and Shuttle Radar Topographic Mission (SRTM) and compared. Finally, depressions mapping and comparative analysis of magnitude and directional change of drainage networks was carried out. Results confirmed better accuracy of MNDWI in separating water bodies. The water bodies area increased by 10.4 % in post-flood monsoon compared to pre-flood monsoon and by 3.8 % in post-flood dry season compared to pre-flood dry season. Geomorphometric analysis indicated that ASTER DEM gave more values of maximum slope, average slope, and standard deviation as compared to SRTM. Aspects distribution algorithm did not work well in low relief regions. The drainage network generated using SRTM DEM was more accurate. The depressions identified were more susceptible to flood events. Change analysis of drainage network (deviating 100–300 m) indicated that 5.22 % points deviated between October, 2004 and 2005 and 3.18 % between February, 2005 and 2006.

Description: Flood inundation modelling in developing countries is severely limited by the lack of high resolution terrain data and suitable imagery to map flood extents. This study assessed the predictive uncertainty of modelled flood extents generated from TELEMAC2D model using low-cost, sparse input data commonly available in developing countries. We studied a river reach characterised by anabranching channels and river islands in eastern India. In this complex fluvial setting, we analysed computational uncertainty as a function of error in both satellite-derived flood-extent maps using a Generalised Likelihood Uncertainty Estimation (GLUE)-based approach. The model performance was quite sensitive to the uncertainty in the inflow hydrograph, particularly close to the flood peak. Evaluation of the flood inundation probability map, conditioned upon deterministic and probabilistic observed flood extents, reveals that the effect of using probabilistic observed data is only evident for portions of the model domain where the model output is free from consistent bias (over or under prediction) likely created by the imperfect terrain data.

Description: In the past canals were developed, and some rivers were heavily altered, driven by the need for good transportation infrastructure. Major investments were made in navigation locks, weirs and artificial embankments, and many of these assets are now reaching the end of their technical lifetime. Since then the concept of integrated water resource management (IWRM) emerged as a concept to manage and develop water-bodies in general. Two pressing problems arise from these developments: (1) major reinvestment is needed in order to maintain the transportation function of these waterways, and (2), it is not clear how the implementation of the concept of IWRM can be brought into harmony with such reinvestment. This paper aims to illustrate the problems in capital-intensive parts of waterway systems, and argues for exploring value-driven solutions that rely on the inclusion of multiple values, thus solving both funding problems and stakeholder conflicts. The focus on value in cooperative strategies is key to defining viable implementation strategies for waterway projects.

Description: Water grids are emerging as a response to water scarcity in many urban areas. These grids are comprised not only of traditional surface and groundwater supplies, but also alternative, climate-independent water sources such as desalination and wastewater recycling, as well as one and two-way pipelines connecting surface-water supplies in different regions. The complexity and heterogeneity of these water supply networks brings new challenges to water management. Water managers need to determine strategies to operate the system in terms of multiple objectives, subject to uncertainty and boundary conditions relating to climate, demand and infrastructure. This paper outlines a framework of methodologies for developing optimal operating plans for short-term planning for water grids, in terms of the objectives of interest.

Description: It is widely recognized that urban development alters infiltration capacity and enhances its spatial variability, but also constrains watercourses into narrow channels making them unable to contain the runoff that is generated by relatively small, but intense, rainfall events. Network of detention basins are designed to reduce the flood peak by temporarily storing the excess storm water and then releasing the water volume at allowable rates over an extended period. This paper shows the use of a distributed hydrological model for the assessment of effectiveness of a network of detention facilities in a heavily urbanized river basin. The distributed hydrological model FEST was used to assess design hydrograph and, in parallel to design the seven detention basins optimized for the specific purpose of maintaining the flow rate within the range of the maximum allowable discharge. This permitted to estimate the design hydrograph considering both the spatial variability of soil infiltration capacity and routing characteristics induced by each detention basins along the main river. Results indicate that on-stream detention ponds can increase duration of the critical event and runoff volume of design flood with possible negative implications on downstream facilities.

Description: The present study evaluates the effects of river run-off regime and hydrological uncertainty on the hydroelectric production of a run-of-river power plant. The mean annual energy from a plant was modeled as a function of run-off regime and design flow, by means of a procedure developed on the mean annual Flow Duration Curves (FDCs) of 15 sample basins in the Umbria Region (Central Italy). Results show that energy output decreases from constant to torrential regimes, following a potential function, and that, the greater the design flow, the greater the rate of decrease. The treatment and validation of these results provided a useful tool for easy identification of optimal design flow, according to the hydrological features of the basin and the target hydroelectric production at the station. Analyses of FDCs with a 20-year return period also showed that the decrease in energy production in dry years and its increase in wet years, compared with the mean annual value, are linearly linked to the design flow. In the present context of possible climate change, this result is presented as the possibility of partially controlling the effects of positive or negative flow rate trends. The results reported here can be applied to any kind of river and hydraulic technology at the power station.

Description: The necessity of long-term dam inflow forecast has been recognized for many years. Despite numerous studies, the accurate long-term dam inflow prediction is still a challenging task. This paper presents an adaptive neuro-fuzzy inference system (ANFIS) based model and evaluates the applicability of categorical rainfall forecast for improvement of monthly dam inflow prediction. In order to obtain appropriate ANFIS model configuration for dam inflow prediction, several models were trained and tested using various numbers of input variables i.e. monthly observed rainfall, relative humidity, temperature, dam inflow and categorical monthly rainfall forecast. The ANFIS based models were configured and evaluated for six major dams of South Korea i.e. Andong, Chungju, Daecheong, Guesan, Soyang and Sumjin having high, medium and low reservoir capacity. The results showed significant improvement in dam inflow prediction for all the selected dams using the ANFIS based model with categorical rainfall forecast compared to the ANFIS based model with only preceding month’s dam inflow and weather data.

Description: This paper proposes a new water transfer triggering mechanism for multi-reservoir system to divert water from abundant to scarce regions with a constant diversion flow in an inter-basin water transfer-supply project. Taking into account of the uncertain nature of inflow, the storage of reservoir is taken as a signal for decision-making to indicate water abundance or water scarcity. In this study, a set of rule curves based on storage of donor reservoir and storage of recipient reservoir are used together to determine when to start water transfer. To initiate water diversion to each recipient reservoir effectively, several water transfer rule curves of the donor reservoir are set for each recipient reservoir respectively in the multi-reservoir system with one donor reservoir and several recipient reservoirs, which is the main difference in comparison with other water transfer triggering mechanisms. In addition, a systematic framework is developed to integrate the water transfer rule curves with hedging rule curves to simultaneously solve the water transfer and water supply problems, since they interact with each other during the operation process. In order to verify the utility of the new water transfer triggering mechanism, an inter-basin water transfer-supply project in China is used as a case study and an improved particle swarm optimization algorithm (IPSO) with a simulation model is adopted for optimizing the decision variables. The results show that the proposed water transfer triggering mechanism can improve the operation performances of the inter-basin system.

Description: Water scarcity is becoming an increasingly relevant issue in many regions of the world as demand for water continues to grow. As a result, the need for finding measures that efficiently allocate increasingly scarce water resources has become a primary topic on the agendas of many water resource management authorities. This paper presents an innovative approach that provides further insight into the connection between hydrological, environmental, and economic aspects along a river basin. In short, it analyzes how land rents along a river basin are affected by managing water pollution along a river basin, given certain hydrological characteristics of the river basin. Results show that, without the implementation of a water management system to control water quality, the negative external effects of upstream water discharges on downstream locations can be internalized through a decrease in downstream land rents. However, the analysis presented in this paper also reveals that it is not only the absence or the presence of a water management system that has a significant impact on the real estate market along the river basin. Moreover, the market outcome also varies with the type of water resources management system implemented.

Description: The use of regional climate model (RCM) outputs has been getting due attention in most European River basins because of the availability of large number of the models and modelling institutes in the continent; and the relative robustness the models to represent local climate. This paper presents the hydrological responses to climate change in the Upper Tiber River basin (Central Italy) using bias corrected daily regional climate model outputs. The hydrological analysis include both control (1961–1990) and future (2071–2100) climate scenarios. Three RCMs (RegCM, RCAO, and PROMES) that were forced by the same lateral boundary condition under A2 and B2 emission scenarios were used in this study. The projected climate variables from bias corrected models have shown that the precipitation and temperature tends to decrease and increase in summer season, respectively. The impact of climate change on the hydrology of the river basin was predicted using physically based Soil and Water Assessment Tool (SWAT). The SWAT model was first calibrated and validated using observed datasets at the sub-basin outlet. A total of six simulations were performed under each scenario and RCM combinations. The simulated result indicated that there is a significant annual and seasonal change in the hydrological water balance components. The annual water balance of the study area showed a decrease in surface runoff, aquifer recharge and total basin water yield under A2 scenario for RegCM and RCAO RCMs and an increase in PROMES RCM under B2 scenario. The overall hydrological behaviour of the basin indicated that there will be a reduction of water yield in the basin due to projected changes in temperature and precipitation. The changes in all other hydrological components are in agreement with the change in projected precipitation and temperature.

Description: In this study, the hydrologic and hydraulic processes occurring in green roofs are analyzed and the similarities and differences in the rainfall-runoff transformation between green roofs and regular catchments are identified. Analytical equations, which can be used to evaluate the long-term average runoff reduction rates, fractions of time when irrigation is needed, and irrigation water requirements of both extensive and intensive green roofs with or without storage layers, are derived by modifying or extending the analytical probabilistic model which was previously developed to model probabilistically the rainfall-runoff processes occurring on regular catchments. The accuracy of these analytical equations is verified by comparing with continuous simulation results. Also demonstrated in this paper are the performances of green roofs with widely different hydrologic designs under arid and humid climate conditions.

Description: A model for the design of detention basin systems is presented that interfaces a simulated annealing (SA) optimization procedure with the U.S. Army Corps of Engineer’s Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS). The optimization model is based upon the simulated annealing method to optimize the size and location of detention basin system including the outlet structures subject to design constraints. The program is implemented in Visual Basic for Applications (VBA) interfacing the simulated annealing model with the HEC-HMS model using an MS Excel environment. The respective result files are created by using a VBA executed Python script to extract the appropriate data from the HEC-HMS project DSS file after each simulation performed for the SA procedure. Example applications include a single detention basin system and multiple detention basin systems considering two scenarios. Though the implementation requires considerable computational effort with respect to the number of hydrologic simulations, simulated annealing proves to be an effective tool in the optimal design of detention basin systems as compared to traditional standards of practice.

Description: Increasing water shortages promote reclaimed water irrigation (RWI), which potentially causes additional contaminants in groundwater. The DRASTIC model has become an important tool to assess specific groundwater vulnerability. In this study, five parameters of the model were kept to calculated intrinsic vulnerability index (IVI). Aquifer media rating is calculated using the weighted average of ratings for all mediums instead of using the major medium rating, and the rating of the impact of vadose zone is adjusted for the clayey soils on the basis of their thickness. Subsequently, a single parameter sensitivity analysis is used to compute the effective weights of those five parameters. The Pearson’s correlation coefficient between IVI and Nemerow’s synthetical pollution Index (NI) of groundwater quality is significantly improved from 0.185 to 0.775 after four steps of revision. The RWI factor, R rr , is introduced to assess specific vulnerability index (SVI) under RWI. The SVI decreases from east to west with the increases in depth to water, clayey soil thickness, and other factors. To manage contamination risk, the study area is divided into preferential zones, feasible zones and unfeasible zones for RWI planning and operation with suggested engineering measures.

Description: This study aims to optimize the water quality monitoring of a polluted watercourse (Leça River, Portugal) through the principal component analysis (PCA) and cluster analysis (CA). These statistical methodologies were applied to physicochemical, bacteriological and ecotoxicological data (with the marine bacterium Vibrio fischeri and the green alga Chlorella vulgaris ) obtained with the analysis of water samples monthly collected at seven monitoring sites and during five campaigns (February, May, June, August, and September 2006). The results of some variables were assigned to water quality classes according to national guidelines. Chemical and bacteriological quality data led to classify Leça River water quality as “bad” or “very bad”. PCA and CA identified monitoring sites with similar pollution pattern, giving to site 1 (located in the upstream stretch of the river) a distinct feature from all other sampling sites downstream. Ecotoxicity results corroborated this classification thus revealing differences in space and time. The present study includes not only physical, chemical and bacteriological but also ecotoxicological parameters, which broadens new perspectives in river water characterization. Moreover, the application of PCA and CA is very useful to optimize water quality monitoring networks, defining the minimum number of sites and their location. Thus, these tools can support appropriate management decisions.

Description: Different water agencies use different modeling tools for water resources planning and management. For example, different jurisdictions in Australia use a variety of river system models and these models vary considerably in approach and assumptions, including different time steps (monthly and daily), flow routing (different types of routing and no routing), ordering solution (optimization and heuristic) and representation of management and operational rules. These fundamental differences in approach make it difficult to integrate existing models of connected river systems at a basin scale. A collaborative joint venture (the eWater CRC) between research, industry and government partners has recently developed an integrated river system modelling tool called “eWater Source” to improve on the existing river system models in Australia. One of the major advances in Source is the implementation of two decision algorithms, heuristic and NetLP approaches, for water distribution modelling in the same modelling platform. This paper describes the implementation of heuristic and NetLP approaches for water delivery under management and operations rules in Source, and compares the performance of the two approaches through a case study in the Goulburn-Broken-Campaspe-Loddon (GBCL) river system in south-eastern Australia. The key performance measures used to compare the approaches include the efficiency and equity of water delivery to water users, impacts on the reliability of supply, agreement with storage operating targets, and model application run time. The results demonstrate that the heuristic approach implemented in Source can replicate the performance of the NetLP approach for a model of reasonable complexity. This is important because the run times of models with heuristic approaches are shorter than models with NetLP approaches, so this will allow more complexity to be represented than was previously practical in equivalent NetLP applications. Agreement between jurisdictions to move to the single river system modelling platform will contribute to overcoming the problems faced by river managers in Australia in transboundary river basins.

Description: Wavelet based flood forecasting models are known to perform better than conventional models, yet the effect of the way wavelet components are combined to develop a model on the forecasting performance, is inadequately investigated. To demonstrate this, two types of wavelet- adaptive neuro-fuzzy inference system (WANFIS), i.e. WANFIS-split data model (WANFIS-SD) and WANFIS-modified time series model (WANFIS-MS) are developed to forecast river water levels with 1-day lead time. To develop these models, first the original level time series (OLTS) is decomposed into discrete wavelet components (DWCs) by discrete wavelet transform (DWT) upto three resolution levels. In WANFIS-SD, all wavelet components are used as inputs while WANFIS-MS ignores the noise wavelet components and utilizes only the effective wavelet components. The effectiveness of the developed models are evaluated through application to two Indian rivers, Kamla and Kosi, which vary significantly in their catchment area and flow patterns. The proposed models are found to forecast river water levels accurately. On comparison, the WANFIS-SD is found to perform better than WANFIS-MS for high flood levels.

Description: Most of the popular hydrological models are intensive data driven hence, it has become a constraint in computing runoff of river basins where the meteorological data availability is scant. Studying environmental impact assessment on runoff has also become complex in many basins due to non-availability of sufficient historic meteorological data. Directly or indirectly, major components of hydrological cycle such as evapotranspiration and soil moisture are dependent on land use pattern at basin scale. Keeping in view of this, in this paper, an attempt was made to propose modification to simple monthly water balance model by integrating potential evapotranspiration with land use coefficients that were derived from the temporal satellite remote sensing data to compute runoff at basin scale. Godavari Basin, India was selected as study basin to demonstrate the approach. Monthly land use coefficients of all land use classes were computed during the calibration process of the model by matching the computed runoff with field runoff. Runoff during the last 18 years (1990–91 to 2007–08) was computed using the developed methodology. Four years datasets were used for model calibration and the rest of the data for model validation. Spatial annual groundwater flux, reservoir flux and domestic water consumption grids were computed using the field data and integrated with the model in computing runoff. From the Nash-Sutcliffe efficiency coefficient, it is found that computed runoff is very well matching the field runoff. The demonstrated approach is found to be more accurate and simple in computing runoff at basin scale in absence of high intensity meteorological data.

Description: Accelerated soil erosion is a threat for the societies due to the loss of ecosystems services. Soil erosion and sediment delivery have been assessed in a small catchment of Central Spain with a new water body, the Pareja Limno-reservoir, located in its outlet. This limno-reservoir was created in 2006 with environmental and recreational purposes in the riverine zone of a large reservoir. Sedimentation risk is an issue of concern regarding limno-reservoirs environmental feasibility. Thus, the study of the soil erosion in the Pareja Limno-reservoir catchment and its sediment delivery seemed of the utmost importance. In this paper we establish an affordable and simple methodology to address it. A soil erosion and deposition monitoring network was installed in the Ompólveda River basin (≈88 km 2 ), which flows into the Pareja Limno-reservoir. Results obtained were related with those from a sedimentation study previously carried out in the limno-reservoir. Gross hillslope erosion in the catchment was 6.0 Mg ha −1  year −1 , which is in agreement with values reported for Mediterranean areas. After subtraction of the deposition measured, a soil loss of 1.2 Mg ha −1  year −1 was found in the catchment. Sediment delivery ratio (SDR) was estimated to be 3.8 %. SDR is low as a result of the low connectivity between the stream network and the limno-reservoir. Some local characteristics may also have a secondary influence in the low SDR value. Results obtained support the environmental feasibility of the Pareja Limno-reservoir from the sedimentation risk perspective. They also demonstrate that the methodology followed allows the assessment of soil loss and sediment delivery at a catchment scale, and the identification of areas where the erosion problems are most severe.

Description: The Mara River in East Africa is currently experiencing poor water quality and increased fluctuations in seasonal flow. Improved water quality will require upstream farmers and foresters to adopt Best Management Practices (BMPs), which might cost them considerably. This study proposes a Payment for Watershed Services (PWS) mechanism. This is a market-based approach, whereby downstream water users would pay upstream watershed service providers towards the costs of BMPs implementation. This study analyzes the technical feasibility and economic viability of adapting selected BMPs and provides cost estimates of a PWS program. Using three criteria of water quality improvement, economic feasibility, and technical suitability, a detailed economic opportunity cost analysis revealed that farmers would indeed incur economic losses for all BMPs except no-till farming. We also developed a multi-criteria (demographic and environmental) methodology for identifying land areas to be placed under BMPs. More than 122,000 ha of land would require BMPs, including a moratorium on agriculture inside the Mau Forest Complex. The initial per hectare opportunity costs across the five highest ranked BMPs ranged from US$ 272 to US$ 926. Using these cost estimates, the paper draws some valuable policy and management insights on how to finance BMP implementation.

Description: Water distribution systems, where flow in some pipes is not measured or storage tanks are connected together, calculation of demand pattern coefficients of the network is difficult. Since, Hazen-Williams coefficients of the network are also unknown; the problem is becoming unintelligible further. The present study proposes a new method for simultaneous calibration of demand pattern and Hazen-Williams coefficients that uses the Ant Colony Optimization (ACO) algorithms coupled with the hydraulic simulator (EPANET2) in a MATLAB code. In this paper demand pattern and Hazen-Williams coefficients are the calibration parameters and measured data consist of nodal pressure heads and pipe flows. The defined objective function minimizes the difference between the measured and simulated values. The new proposed method was tested on a two-loop test example and a real water distribution network. The results show that the new calibration model is able to calibrate demand pattern and Hazen-Williams coefficients simultaneously with high precision and accuracy.

Description: The share of renewable resources in electricity generation, e.g. in Germany, is increasing. The power sector is thus becoming more dependent on climate/weather parameters. During the summer months of the last decade, numerous thermal power plants in Europe had to be throttled due to water shortages and high water temperatures. At the same time, Europe was confronted with a reduction in hydropower production. One method of securing a future electricity supply is to increase the reliability of the water supply for power plants. In this paper, scenarios are presented for future electricity production by hydropower and thermal power plants in the Elbe river basin. Electricity production in hydropower plants will decline by approximately 13 % by 2050. This decline is due to climate change and it could be compensated for by optimizing and modernizing existing hydropower plants. Due to higher efficiencies and the conversion of plant cooling systems, no water shortages are expected in most thermal power plants. However, water shortages are expected to affect the plants in the city of Berlin. Inter- and intra-basin water transfers constitute a possible adaptation option. While the transfer of water from the river Oder would be the most cost-efficient solution from Berlin’s perspective, the transfer of water from the river Elbe would have additional positive effects in the upstream Spree river sub-basin.

Description: This study was accomplished using 26 locations in the major ecological zones of Nigeria as well as different classes of residential buildings and different levels of water consumption. For each location, house dwelling class and level of water consumption, a water balance approach was used to assess the proportion of water demand that can be met by rainwater. Results obtained indicate that for all the locations in the rainforest zone and some parts in the guinea savanna zone, over eighty percent (80 %) of water demand of those living in bungalows can be met by rainwater. Rainwater harvesting potential was found to be a power function of rainfall coefficient of variation, with coefficient α and exponent β. High correlation coefficients (0.881 ≤  R 2  ≤ 1) were obtained between coefficient α and roof area per capita. Also, high correlation coefficients (0.847 ≤  R 2  ≤ 0.992) were obtained between exponent β and roof area per capita.

Description: Long term water demand forecasting is needed for the efficient planning and management of water supply systems. A Monte Carlo simulation approach is adopted in this paper to quantify the uncertainties in long term water demand prediction due to the stochastic nature of predictor variables and their correlation structures. Three future climatic scenarios (A1B, A2 and B1) and four different levels of water restrictions are considered in the demand forecasting for single and multiple dwelling residential sectors in the Blue Mountains region, Australia. It is found that future water demand in 2040 would rise by 2 to 33 % (median rise by 11 %) and 72 to 94 % (median rise by 84 %) for the single and multiple dwelling residential sectors, respectively under different climatic and water restriction scenarios in comparison to water demand in 2010 (base year). The uncertainty band for single dwelling residential sector is found to be 0.3 to 0.4 GL/year, which represent 11 to 13 % variation around the median forecasted demand. It is found that the increase in future water demand is not notably affected by the projected climatic conditions but by the increase in the dwelling numbers in future i.e. the increase in total population. The modelling approach presented in this paper can provide realistic scenarios of forecasted water demands which would assist water authorities in devising appropriate management strategies to enhance the resilience of the water supply systems. The developed method can be adapted to other water supply systems in Australia and other countries.

Description: Disregarding water as a key sustainable development has led to the water crisis in Iran. This problem is the biggest factor for marginalizing the planning and long-term management of water. The sustainable development policies in water resources management of IRAN require consideration of the different aspects of management that each of them demands the scientific integrated programs. Optimal use of inter-basin surface and groundwater resources and transfer of surplus water to adjacent basins are important from different aspects. The purpose of this study is to develop an efficient optimization model based on inter-basin water resources and restoration of outer-basin water resources. In the proposed model the three different objectives are as follow supplying inter-basin water demand, reducing the amount of water output of the boundary of IRAN and increasing water transfer to adjacent basins (Urmia Lake basin) are considered. In this model, water allocation is done based on consumption and resources priorities and groundwater table level constraints. In this research, the non-dominate sorting genetic algorithm is used for performing the developed model regarding the complexity and nonlinearity of the objectives and the decision variables. The optimal allocation of each water resources and water transfer to adjacent basin can be determined by using of proposed model. Optimal allocation policy presented based on optimal value and planning horizon. The results show that we can transfer considerable volume of water resources within the basin for restoration the outside basin and prevent the great flow of water by the border rivers applying the optimal operation policy.

Description: Water resources policy making often involves consideration of a broader scope of environmental, economic, and social issues. This inevitably complicates policy making since consensus among multiple stakeholders with different interests is needed to implement decisions. This work employs several practical and popular voting methods to solve a multi-stakeholder hydro-environmental management problem. Conventionally, voting methods or social choice rules have been applied for consensus development in small groups and elections. This work combines voting methods with a Monte-Carlo selection, in order to help with social choice making under uncertainty. This process is intended to aid decision-makers with understanding of the risks associated with potential decision alternatives. The Sacramento-San Joaquin Delta’s water export conflict is solved here as a benchmark problem to illustrate the proposed framework for social decision making and analysis under uncertainty.

Description: A simulation model is developed to understand the dynamic behavior of a hydraulically coupled multiple reservoir system when operated in real-time. An object-oriented simulation environment conceived on the principles of system dynamics (SD) is used for the development of the model. The modeling process consists of developing causal loop, stock and flow diagrams, and carrying out simulations using difference equations to integrate stocks. Unlike traditional simulation environments, modeling using SD principles will aid in the analysis of the system by a series of interconnecting processes and functional relationships. Also, the feedback loops that influence variable values and causal relationships in space and time can be clearly understood using SD-based simulation. Performance measures are developed to quantify the system performance in making decisions regarding actual implementation of operating rules. A simulation model based on a real-life hydropower reservoir system in the Province of Manitoba, Canada is developed. Dynamics of the multiple reservoir operation suggest that in a serial system of reservoirs, the operational decision taken at one reservoir will have effect on the other reservoir. The behavior of the reservoir system for extreme events is also observed and conclusions relevant to real-time operation of the systems are drawn. The simulation models developed in this study provide global description of a hydraulically coupled reservoir system with ability to easily model dynamic processes to obtain operational release decisions that can be adopted in real-time.

Description: The forecast of the sediment yield generated within a watershed is an important input in the water resources planning and management. The methods for the estimation of sediment yield based on the properties of flow and sediment have limitations attributed to the simplification of important parameters and boundary conditions. Under such circumstances, soft computing approaches have proven to be an efficient tool in modelling the sediment yield. The focus of present study is to deal with the development of decision tree based M5 Model Tree and wavelet regression models for modeling sediment yield in Nagwa watershed in India. A comparison is also performed with the artificial neural network (ANN) model for streamflow forecasting. The root mean square errors (RMSE), Nash-Sutcliff efficiency index (N-S Index), and correlation coefficient (R) statistics are used for the statistical criteria. A comparative evaluation of the performance of M5 Model Tree and wavelet regression versus ANN clearly shows that M5 Model Tree and wavelet regression can prove more useful than ANN models in estimation of sediment yield. Further, M5 model tree offers explicit expressions for use by design engineers.

Description: Combined simulation-optimization approaches have been used as tools to derive optimal groundwater management strategies to maintain or improve water quality in contaminated or other aquifers. Surrogate models based on neural networks, regression models, support vector machies etc., are used as substitutes for the numerical simulation model in order to reduce the computational burden on the simulation-optimization approach. However, the groundwater flow and transport system itself being characterized by uncertain parameters, using a deterministic surrogate model to substitute it is a gross and unrealistic approximation of the system. Till date, few studies have considered stochastic surrogate modeling to develop groundwater management methodologies. In this study, we utilize genetic programming (GP) based ensemble surrogate models to characterize coastal aquifer water quality responses to pumping, under parameter uncertainty. These surrogates are then coupled with multiple realization optimization for the stochastic and robust optimization of groundwater management in coastal aquifers. The key novelty in the proposed approach is the capability to capture the uncertainty in the physical system, to a certain extent, in the ensemble of surrogate models and using it to constrain the optimization search to derive robust optimal solutions. Uncertainties in hydraulic conductivity and the annual aquifer recharge are incorporated in this study. The results obtained indicate that the methodology is capable of developing reliable and robust strategies for groundwater management.

Description: Vegetation restoration is helpful in preventing soil erosion but aggravates water scarcity, thus resulting in soil desiccation on the wind–water erosion crisscross region (WWECR) of the Loess Plateau in Northwestern China. However, no guideline currently exists on the selection of plant species and density for restoration purposes. Based on the process model of soil water-carrying capacity for vegetation (SWCCV) originally developed in this region, this study validated the model under a broad range of weather regimes, soil types, and land uses. The SWCCV model was applied as a diagnostic tool to obtain insights into the separate effects of vegetation density and land use on soil water dynamics on the WWECR of the Loess Plateau. Results showed that the total water loss at semi-natural grasslands was close to rainfall while significantly decreasing runoffs, thus indicating that semi-natural grass was suitable for vegetation restoration on the WWECR. If Caragana korshinskii is planted for agronomic and economic benefits, a density of 3,400 trees ha −1 will yield the most optimal soil water conservation benefits at study site. Our recommended land use and vegetation density were directive and instructional for vegetation restoration on the WWECR and that our modeling approach could be extended to applications in other arid and semi-arid regions.

Description: MATLAB ™ software named PRESUD (Pressurized Subunit Design) was developed to identify the optimum solid set sprinkler irrigation subunit design with a criterion of minimizing the annual water application cost (C T ). This C T is defined as the cost per cubic meter of water applied to the soil for crop use. In this study, only rectangular subunits are considered, using an iterative method for calculating the lateral and manifold pipelines. The results indicate that water cost (C w ) , which includes the investment and operation costs for pumping water from the source to the subunit inlet, makes up 75 % of C T . Another important factor is energy cost, which comprises 14 % of C T . The remaining variables, such as sprinkler spacing and layout, or application rate (AR a ), have a lower impact on C T . In cases of use groundwater, the proportion of energy cost in C W can reach 40 %; thus, energy is an important part of C T . Results shows that the criterion of limiting the maximum difference in pressure heads in the irrigation subunit (Δh 〈 20 %), widely used when designing a sprinkler irrigation subunit, does not always lead to a minimum C T , and the use of tools such as PRESUD can help obtain better solutions.

Description: Assessing the risks of agricultural management practices on agro-ecosystem sustainability has special relevance in Ohio, USA due to the states prominence in agricultural production. However, identifying detrimental management practices remains controversial, a situation that may explain the inability to halt the recurring harmful algal blooms in inland waters, or the build-up of nutrients in the agricultural soils. Thus, detailed and accurate information is required to identify soils and water susceptible to degradation, and to support counteractive remedial measures. In this study soil and water spectral reflectance data were acquired with an Analytical Spectral Device, and modeled with laboratory measured physical and chemical properties using the Analysis of Variance (ANOVA) and decision trees. Results reveal no site differences in pH for the water, but the differences in electrical conductivity (EC) were significant. Similarly, the pH for soils did not vary significantly with depth increments. However, the no till (NT) managed soils had significantly higher pH. EC varied with depth of the water, whereas the soil carbon: nitrogen (C/N) ratio varied with management in 4 out of 5 sites. Finally, this study shows that remotely sensed data can be utilized to effectively characterize agricultural management practices based on inherent soil and water properties, thus providing information critical for assessing the efficacy of Water Quality Trading initiatives.

Description: The impoundment of the Three-Gorges-Dam (TGD) significantly alters the flow regimes in Poyang and Dongting Lakes, the two largest freshwater lakes in China by reducing river discharge. This work aims to investigate the impoundment effects of the TGD on lake outflow and water level and clarify dynamic mechanism for the hydrological responses of both lakes to the TGD impoundment based on the typical case study. A hydrodynamic model is set up to simultaneously simulate hydrodynamics in the two lakes and the middle Yangtze River. Results show that TGD induces profound changes of the flow regimes in both lakes. The effects dynamically change with the TGD-induced Yangtze River discharge alteration, and are highly heterogeneous in space due to the complicated interactions between the lakes and the Yangtze River. The impoundment of the TGD accelerates Poyang Lake drainage. But that is not all for Dongting Lake, the TGD impoundment also reduces its water supply from the Yangtze River. The results from this work improve the understanding of the TGD impacts on the downstream river-lake system and provide scientific evidences for formulating better scheme for water resources management in this region.

Description: International society has begun to consider river basins and the coastal zone as one management unit that requires an ecosystem approach. Various countries have undertaken initiatives since the 1970s and have improved the approach to integrated coastal zone management. Brazil has not been one of them. Its sector-based approach to most environmental issues started in the 1980s with the National Environmental Policy Act (Law 6,938/1981). The National Coastal Zone Management Plan (NCZMP) was then approved by Law 7,661 in 1988. Shortly thereafter, the 1988 Brazilian Constitution was enacted, which established the environment as a common good to be used by the entire society but in such a way as to prevent environmental degradation and conserve its quality for present and future generations. The National Water Resources Policy (NWRP) was not enacted until 1997 (Law 9,433/1997). This law established that water resource management in Brazil must take into account estuarine ecosystems and the coastal zone, using an integrated approach. Only in 2006 did the National Water Resources Council (NWRC) create a technical chamber dedicated to developing regulatory measures for integrated management in Brazil. There has been substantial discussion and various proposals to implement it, as outlined in this article. This paper concludes with suggestions for implementing integrated river basin and coastal zone management in Brazil.

Description: An accurate estimation of reference evapotranspiration (ET 0 ) is of paramount importance for many studies such as hydrologic water balance, irrigation system design and management, crop yield simulation, and water resources planning and management. In the present study, Blaney-Criddle, Jensen-Haise and Hargreaves (temperature based), Priestley-Taylor, Radiation and Makkink (radiation based) and, Pan Evaporation and Christiansen (pan evaporation based) methods have been evaluated and recalibrated with respect to FAO-56 Penman-Monteith method for estimating daily ET 0 in the semi-arid Tirupati, Nellore, Rajahmundry, Anakapalli and Rajendranagar sites of Andhra Pradesh, India. Recalibrated Blaney-Criddle (temperature based), Radiation (Radiation based) and Christiansen (Pan evaporation based) methods showed a satisfactory performance at the sites. Further, recalibrated Blaney- Criddle method showed relatively better performance than Radiation and Christiansen methods in the daily ET 0 estimation. Recalibrated Blaney- Criddle method may therefore be adopted at the sites selected for the present study and also at the sites with similar climatic conditions for satisfactory daily ET 0 estimation.

Description: A three dimensional model is presented for the simulation of seawater intrusion in coastal aquifers by considering the development of a transition zone and thus the variable density flow approach. The model is applied to a heterogeneous coastal aquifer to study the effects of the pumping rate, the salinity of freshwater inflow and the thickness of the aquifer, on the degradation of pumped water quality through wells in certain location. Even for an optimum pumping scheme solution based on a simple two-dimensional flow model, we simulate freshwater degradation in pumped water which depends on the salinity of freshwater inflow and aquifer thickness.

Description: Water Scarcity encompasses both permanent and occasional water resources shortages. Measures to combat water scarcity are of different nature dependent on whether they intend to withstand permanent or occasional water deficiency. It is the aim of this paper to discuss and propose a systematic framework for the evaluation of measures of the Contingency Plan of a drought affected area, so that the measures are compatible and complementary to the long term Strategic Plans. For this reason the establishment of two sets of criteria is proposed, the beneficial and the constraining criteria. The beneficial criteria are those representing the short term good performance, whilst the constraining criteria express the incompatibility with the long term Strategic Plans and the long term negative impacts to the environment and the society. The beneficial criteria are aggregated by applying the widely-used multicriteria method of the weighted Euclidean Distance. The compatibility of the constraining criteria with the beneficial criteria is expressed by the use of suitable fuzzy implications. Finally a simple weighted sum is used in order to take into account both the beneficial criteria and the compatibility between the beneficial and constraining criteria. Based on this approach the selection and prioritisation of measures is enhanced leading to a more balanced and realistic defence against drought and water shortage. A numerical application is presented for illustrating the proposed methodology taking the city of Heraklion (Crete) as a case study.

Description: We developed and applied a computational model for simulating unsteady flow in a drainage network of a boreal forested peatland site. The input to the model was the hourly runoff produced by a hydrological model. The simulations of the flow in the ditch network were performed using an iterative procedure for solving the Saint-Venant equations that govern the flow in each of the network channels. These equations were solved separately for each ditch branch, and the flow depths at the junctions were corrected using the method of characteristics. The model was applied to the drainage network of a peatland catchment in Eastern Finland over a period of 15 months. Because flow resistance in the ditches depended strongly on flow conditions, flow resistance (Manning’s n ) was introduced as a function of discharge. The model was calibrated and validated against field data and the simulation results were further applied to assess erosion risk. The highest risk of erosion occurred during long lasting flows induced by snowmelt at ditch sections with a steep slope and a large upstream area. These model results can aid in the design and siting of water protection measures within the drained area.

Description: A comparison study of meteorological, hydrological and agricultural drought responses to climate change resulting from different General Circulation Models (GCMs), emission scenarios and hydrological models is presented. Drought variations from 1961–2000 to 2061–2100 in Huai River basin above Bengbu station in China are investigated. Meteorological drought is recognized by the Standardized Precipitation Index (SPI) while hydrological drought and agricultural drought are indexed with a similar standardized procedure by the Standardized Runoff Index (SRI) and Standardized Soil Water Index (SSWI). The results generally approve that hydrological and agricultural drought could still pose greater threats to local water resources management in the future, even with a more steady background to meteorological drought. However, the various drought responses to climate change indicate that uncertainty arises in the propagation of drought from meteorological to hydrological and agricultural systems with respect to alternative climates. The uncertainty in hydrological model structure, as well as the uncertainties in GCM and emission scenario, are aggregated to the results and lead to much wider variations in hydrological and agricultural drought characteristics. Our results also reveal that the selection of hydrological models can induce fundamental differences in drought simulations, and the role of hydrological model uncertainty may become dominating among the three uncertainty sources while recognizing frequency of extreme drought and maximum drought duration.

Description: Economic theory generally assumes that consumers respond to marginal price, which is the price of the last unit of goods consumed, when making economic decisions. However, this assumption may not hold for goods with multi-block rate schedules. This paper explores the effects of water price information on residents’ behaviors under increasing block tariffs. The empirical evidence from the study suggests the middle-income groups respond to average price, which is based on the price level given by total fees divided by total consumption. This evidence supports the hypothesis that the incremental block tariffs are actually treated the same as uniform pricing for the middle-income group, while the highest income group is not sensitive to price changes. On the contrary, residents of the two lowest income groups respond to marginal price and probably go further to compare prices of different blocks and set consumption at kink points of price schedules to achieve maximal welfare. This study also finds that a higher second block price promotes consumption at kink points, and increased payments in first block consumption lead to less incentive to induce discrete choice behavior.

Description: A survey of young adults was conducted at several 3rd level agricultural institutions across Ireland over a 6-month period. The results from the agri-student survey were compared and contrasted with those of an identical survey of private well owners. Students ( n  = 246) scored significantly lower than well owners ( n  = 245) in two developed metrics, namely “groundwater source awareness” and “groundwater contamination awareness” ( p  〈 0.001). Future “environmental custodians” are not well informed of the human health risks associated with poor groundwater management or of potential amelioration procedures. For example, just 7 % of young respondents exhibited an awareness of the purpose or presence of a sanitary seal; while only 17.5 % were aware of the presence or purpose of a well liner. Results suggest that neither intergenerational nor institutional knowledge transfer pertaining to groundwater protection or drinking water quality is prevalent. A Bayesian clustering method identified four distinct “awareness groups” within an amalgamated dataset ( n  = 476). Clusters comprised four predictors: presence of an elderly householder (predictor importance = 0.91), residence within the household during well design (predictor importance = 0.55), presence of an infant or young child (≤5 years) in the household (predictor importance = 0.48) previous instance of gastrointestinal illness or symptoms within the household (predictor importance = 0.31) The results of this research may be used to inform future risk management, communication and knowledge transfer policies, which are currently required to ensure the safeguarding of private groundwater supplies both in Ireland and further afield.

Description: Intensified use of nitrogen based fertilizers in agriculture has resulted in a significant increases in soils and groundwater nitrate concentrations all over the world. Here we propose a new coupled model which describes the physical transport and biogeochemical dynamics of the water and nitrogen compounds in a soil-water-plant-groundwater system. Our model takes into account water infiltration into an unsaturated porous medium, the complex biogeochemical cycle of nitrogen in soils, nitrate leaching from the agricultural system toward the aquifer’s water table, and the dispersion of nitrates in the groundwater. We calibrate our model and analyse the influence of soil type, precipitation or irrigation regime and fertilization schedules on leaching to groundwater as well as the temporal and spatial evolution of the nitrate pollutant plume in the aquifer. Simulations indicate that in order to achieve high crop yields while minimizing nitrogen loading to soils and groundwater we need to create an optimal balance between the amount of chemical fertilizers and water applied to crops on one hand, and the amount of nitrate and water used by plants on the other. We find that medium soils are more suitable for a sustainable corn production than coarse soils, ensuring both higher yield and less nitrate pollution of the aquifer. Regardless of soil type and irrigation schedule, a gradual fertilization throughout the plant life cycle reduces the potential for leaching and aquifer pollution. For medium soils, a more modest irrigation schedule results in more nitrate available for crops and less net leaching to the groundwater.

Description: Rainfall is one of the most complicated effective hydrologic processes in runoff prediction and water management. Artificial neural networks (ANN) have been found efficient, particularly in problems where characteristics of the processes are stochastic and difficult to describe using explicit mathematical models. However, time series prediction based on ANN algorithms is fundamentally difficult and faces some other problems. For this purpose, one method that has been identified as a possible alternative for ANN in hydrology and water resources problems is the adaptive neuro-fuzzy inference system (ANFIS). Nevertheless, the data arising from the monitoring stations and experiment might be corrupted by noise signals owing to systematic and non-systematic errors. This noisy data often made the prediction task relatively difficult. Thus, in order to compensate for this augmented noise, the primary objective of this paper is to develop a technique that could enhance the accuracy of rainfall prediction. Therefore, the wavelet decomposition method is proposed to link to ANFIS and ANN models. In this paper, two scenarios are employed; in the first scenario, monthly rainfall value is imposed solely as an input in different time delays from the time (t) to the time (t-4) into ANN and ANFIS, second scenario uses the wavelet transform to eliminate the error and prepares sub-series as inputs in different time delays to the ANN and ANFIS. The four criteria as Root Mean Square Error (RMSE), Correlation Coefficient ( R 2 ), Gamma coefficient (G), and Spearman Correlation Coefficient ( ρ ) are used to evaluate the proposed models. The results showed that the model based on wavelet decomposition conjoined with ANFIS could perform better than the ANN and ANFIS models individually.

Description: Reference evapotranspiration (ET 0 ) data are desirable for assessing crop water requirements and irrigation needs. A large number of methods have been developed for assessing ET 0 from meteorological data. In several places of the world, the existing network of weather stations is insufficient to capture the spatial heterogeneity of this variable The purpose of this work is to investigate whether it is possible to attain reliable estimation of ET 0 only on the basis of the remote sensing-based surface temperature (T s ) data by Blaney-Criddle (B-C) model under a semi arid environment of Iran. This study has assumed that the daytime surface temperature at the cold pixel obtained from the AVHRR/NOAA sensor can be used instead of air temperature in the Blaney-Criddle (BC) equation for ET 0 estimation in irrigated area. For this purpose, 61 NOAA- AVHRR satellite images acquired between June and September in 2004 and 2005 and weather data measured at two weather located in two irrigation regions with sugar cane located in Khuzestan plain in the southwest of Iran were used to calibrate and test the B-C model. The FAO-56 Penman–Monteith model was used as a reference model for assessing the performance of the calibrated BC model. The results show that calibrated B-C model provided close agreement with the reference values, with an average RMSE of 1.0 mm day −1 and a R 2 of 0.91.

Description: A compromise programming based model has been developed for maximizing food production with minimum allocation of available water at watershed scale after meeting human, livestock and environmental needs under different scenarios. Agricultural water allocation in conjunction with available land resources under a set of constraints has been examined. The formulated model has the potential to analyze the implications of water availability on agricultural water allocation plans, and consequently food production. A case study in Indian Himalayan region, where despite abundant availability of water, rainfed agriculture is mostly practiced by majority of farmers with a primary objective of self-sufficiency in food production, well demonstrates the applicability of the developed model. Three distinct scenarios affecting water availability were considered. Analysis of imposition of fixed mandatory outflows of 20 to 70 % (as per water source) for satisfying environmental needs with present production mix revealed water scarcity within the study watershed ranging from 4 to 66 % across various quarters of an year, which necessitates optimum utilization of rainfed fallow land by allocating it to high value crops ginger and lentil (6 to 32 times more than existing allocation) on one hand, and drastic reduction (76 to 100 %) of area under all irrigated crops (except onion with 4–6 times increase) on the other, to achieve the conflicting objectives. The compromise plans also suggested increase (by 14 % in environmental watershed scenario) or decrease (by 29 % in degraded watershed scenario) in size of livestock population as per scenario based water availability. Overall, the compromise plans were successful in achieving a high percentage (〉93 %) of ideal values of the objective functions, which were 155 to 170 % of existing food production and 71 to 85 % of existing water utilization across the scenarios. The proposed optimization model has the potential for application in identical agro-climatic settings to enhance food production in an environmental friendly manner.

Description: Climate variability due to the greenhouse effect has important implications on hydrological processes and water resources systems. Indeed, water availability, quality and streamflow are very sensitive to changes in temperature and precipitation regimes whose effects have to be fully considered in current water management and planning. International literature proposes several models, attempting to assess accurately the available water resources under stationary and changing climatic conditions at different spatial and temporal scales. In order to assess the potential impacts of climate change on surface and groundwater resources water availability in a Southern area of Italy, a conceptual hydrologic model, the TOPDM, was applied at daily scale to simulate the hydrological processes in the Belice river basin, located in Sicily and which feeds an artificial lake. The analysis of climatic forcings trend provided the parameters needed in order to generate synthetic climate forcing series through the use of the AWE-GEN, an hourly weather generator, able to reproduce the characteristics of hydro-climatic variables and their statistical properties. . The hydrological model was used to estimate the basin water balance components and the surface and groundwater availability, at annual and monthly scale, in a no trend scenario, representing the current climate conditions, and in three different groups of scenarios, in which a decrease of precipitation, an increase of temperature, and a combination of these effect were reproduced. The application of TOPDM to the test basin provided some important conclusions about the implications of climate change in the Southern part of Italy. Results showed that runoff and evapotranspiration reflect variations in precipitation and in temperature; in particular the negative trend in precipitation determines a decrease in surface and groundwater resources, and this effect is intensified in the scenarios that include an increase in potential evapotraspiration as well. The consequences of changes on water supply system were also analyzed through a simple balance evaluation of the lake water reservoir, in order to assess the possible impacts on the resource managements. Results indicated an exacerbation of the water resources stresses, in which water scarcity is already an important issue for water resource management. The analysis provides useful information about the quantification of the potential effects of climate change in the area of study, in order to develop new strategies to deal with these changes.

Description: In this article, a rainfall forecasting model using monthly historical rainfall data and climate indices is developed by incorporating wavelet analysis (WA) and second order volterra nonlinear model. The monthly rainfall time series and large-scale climate index time series are decomposed using wavelets into a certain number of component subseries at different temporal scales. The lag relationship between the rainfall anomaly and each potential predictor is identified by cross correlation analysis with a lag time of at least 1 month at different temporal scales. The components of predictor variables with known lag times are then integrated using a second order Volterra model. Further, orthogonal least squares method is used to reduce the redundant variables and select the significant variables to be included into the final forecast model. The proposed multivariate wavelet nonlinear rainfall forecasting method is examined with over three places in India, and compared to the traditional ANN model based on the original time series and linear wavelet regression model. The models are trained with data from the 1916 to 1968 period and then tested in the 1968–1989 period. The results show that the proposed wavelet nonlinear model provides considerably more accurate monthly rainfall forecasts for the three selected places in India than the traditional regression model, neural networks model and the wavelet based linear model. It was seen that for the proposed models and other models also, both the past rainfall and the large-scale climate signals were useful in forecasting the future.

Description: Pressure control is one of the main techniques to control leakages in Water Distribution Networks (WDNs) and to prevent pipe damage, improving the delivery standards of a water supply systems. Pressure reducing stations (PRSs) equipped by either pressure reducing valves or motor driven regulating valves are commonly used to dissipate excess hydraulic head in WDNs. An integrated new technical solution with economic and system flexibility benefits is presented which replaces PRSs with pumps used as turbines (PATs). Optimal PAT performance is obtained by a Variable Operating Strategy (VOS), recently developed for the design of small hydropower plants on the basis of valve time operation, and net return determined by both energy production and savings through minimizing leakage. The literature values of both leakages costs and energy tariffs are used to develop a buisness plan model and evaluate the economic benefit of small hydropower plants equipped with PATs. The study shows that the hydropower installation produces interesting economic benefits, even in presence of small available power, that could encourage the leakage reduction even if water savings are not economically relevant, with consequent environmental benefits.

Description: Construction of river diversion barrages produces a shallow reservoir, called the pond, which is used more often for flow balancing between the inflows of the river and the outflows of the off-taking canal. However, deposition of sediment in the pond due to the relatively low velocities reduces the pond capacity. The current study investigates the effectiveness of gate operation and variations of other parameters in flushing out these sediment mounds, or shoals, from the barrage pond. Data from laboratory experiments on a scaled model of a prototype barrage is used to train and test different Artificial Neural Network (ANN) models of the system. The models map the relationship between flushing efficiency of a sediment shoal from the upstream of a barrage, and the parameters river discharge, barrage pond depth and area of gate opening, position of the sediment shoal with respect to the barrage. The ANN models are then used to study the effect of different parameters on the sediment flushing efficiency. Apart from river discharge and net area of gate opening, upstream pond depth is also found to have a significant effect on flushing efficiency, with a general trend of decrease in efficiency with increase in pond depth becoming apparent. Efficacy of different gate opening pattern is also tested, with the ‘inverted arch’ gate opening pattern proving to be the most efficient when compared with ‘arch’ and ‘uniform’ gate opening.

Description: Change point detection is an effective tool to identity whether the hydrological data are of consistency. In this paper, Pettitt test was first used to detect change point for annual rainfall and runoff time series in 6 selected sub-watersheds of Luanhe river basin in Northeast part of China. Then we presented a method to detect change point according to the law of mutual change of quality and quantity in variable fuzzy sets. We chose the mean of time series as assessment index as in other change point detection methods, and defined 95 and 5 % quantiles of the time series as the supremum and infimum respectively. We selected a reference period (for example, the first 10 points of the time series) as the stationary period, and after the reference period, we checked the mean value of the time series point by point. We used this method in the 6 sub-watersheds of Luanhe river basin. The results of the 2 methods showed that most annual rainfall time series had no change point, and some annual runoff time series had change point in 1979 or 1981. Comparison of the 2 methods was made, and it indicated that Pettitt test provided reference for variable fuzzy sets method, but the latter provided more reasonable results than Pettitt test in this study. This method can also be used in other natural time series.

Description: The Walla Walla Basin, in Eastern Oregon and Washington, USA, faces challenges in sustaining an agricultural water supply while maintaining sufficient flow in the Walla Walla River for endangered fish populations. Minimum summer river flow of 0.71 m 3 /s is required, forcing irrigators to substitute groundwater from a declining aquifer for lost surface water diversion. Managed Aquifer Recharge (MAR) was initiated in 2004 attempting to restore groundwater levels and improve agricultural viability. The Integrated Water Flow Model (IWFM) was used to compute surface and shallow groundwater conditions in the basin under water management scenarios with varying water use, MAR, and allowable minimum river flow. A mean increase of 1.5 m of groundwater elevation, or 1.5 % of total aquifer storage, was predicted over the model area when comparing maximum MAR and no MAR scenarios where minimum river flow was increased from current level. When comparing these scenarios a 53 % greater summer flow in springs was predicted with the use of MAR. Results indicate MAR can supplement irrigation supply while stabilizing groundwater levels and increasing summer streamflow. Potential increase in long-term groundwater storage is limited by the high transmissivity of the aquifer material. Increased MAR caused increased groundwater discharge through springs and stream beds, benefiting aquatic habitat rather than building long-term aquifer storage. Judicious siting of recharge basins may be a means of increasing the effectiveness of MAR in the basin.

Description: The primary goal of this study is to identify floodplains that are in large river basins and could potentially undergo renaturalization of their hydrologic functions. The study area is the Paraíba do Sul River Basin (55,400 km 2 ), which is located in southeastern Brazil. The field work included the application of geoprocessing techniques ( ArcGIS 10 and ENVI 4.7 ) for the delineation and individualization of the floodplain, and the following characteristics were surveyed: area, perimeter, circularity index and urbanization index. Discriminant and cluster analyses ( SPSS 15 ) were performed, and 77 floodplains were found that exhibited a wide variation in area (0.13 to 1,540 km 2 ) and perimeter (1.8 to 4,200 km), low circularity indices (〈0.52), and a low average urbanization index (18.9 %). The floodplains were grouped according to how well the renaturalization of their hydrologic functions could be managed and categorized as follows: a) low management potential (9 units); b) medium management potential (15 units); and c) high management potential (52 units). The discriminant analysis correctly classified 100 % of the cases, which indicates that the model has a high predictive ability and can accurately classify the management potential of floodplains.

Description: Regionalization methods are often used in hydrology for frequency analysis of floods. The hydrologically homogeneous regions should be determined using cluster analysis instead of the geographically close stations. In view of the ongoing environmental and climate changes in the Northeastern of India, regionalization of homogeneous rainfall region is essential to lay out an effective flood frequency analysis of this region. The choice of appropriate cluster approach used according to the data of the basin is also significant. In the context of this study, total precipitation data of stations operated by Indian Meteorological Department (IMD) in Northeastern of India basins for cluster analysis are used. Further, five cluster validity indices, namely Partition Coefficient, Partition Entropy, Extended Xie-Beni index, Fukuyama-Sugeno index and Kwon index have been tested to determine the effectiveness in identifying optimal partition provided by the fuzzy c mean clustering algorithm (FCM). A comparison is also performed using K - Mean clustering algorithm. Additionally, regional homogeneity tests based on l -moments approach are used to check homogeneity of regions identified by both cluster analysis approaches. It was concluded that regional homogeneity test results show that regions defined by FCM method are sufficiently homogeneous for regional frequency analysis.

Description: Intended for comprehensive assessment of water usage in agricultural for food production and to address its future, it is essential to scrutinize the dynamic behavior of crop production and its water footprint and virtual water trade. Through the current research a System Dynamic model that can be applied to estimate crop production, water footprint, and virtual water nexus was developed. The system could be applied to explore how water footprint of crop production and consumption change under proposed planned scenarios which differ from each other in terms of main drivers of change. The drivers of change include population, per capita crop consumption, crop trade patterns, crop yield, and climate change impact. The system is developed to be applied at the country level. A case study from Egypt was analyzed applying the developed system. Where, water footprint of wheat production (green, blue, and grey water), consumption (internal, import and export), and its virtual water balance for years 2010 to 2050 were analyzed under proposed planned scenarios. These proposed planned scenarios were varying in wheat trade pattern strategies and impact of climate change on wheat water consumption and its yield.

Description: Due to large-scale agricultural irrigation and industrial production, groundwater had been excessively employed to benefit the economy development and life improvement in Chikugo-Saga plain since the middle of last century, which led to many environmental problems such as land subsidence, flooding inundation and water shortage. In order to mitigate the impact of environmental hazards, some water supply projects have been performed to substitute surface water for groundwater since 1970s. For the purpose of comprehending the influence of substitute water projects on groundwater withdrawals, a tempo-spatial groundwater withdrawals assessment model with the resolution of one month in time and one kilometer in space was initially established based on various data concerning meteorology, agriculture, land use, soils, surface water consumption and groundwater utilization by using GIS. According to the development of the substitute water projects, a 28-year study period 1979–2006 was then divided into four stages (i.e. 1979–1984, 1985–1995, 1996–2000 and 2001–2006) and the tempo-spatial distribution of groundwater withdrawals for each stage was represented by means of the proposed model. The tempo-spatial variation of groundwater withdrawals for various water use categories under the effect of substitute water projects was finally analyzed by comparing the distributions of groundwater withdrawals at different stages. The results show that with the advance of the substitute water projects studied, the groundwater pumpage for irrigation, industry or waterworks varies geographically and phasically in the plain. From the first stage to the last stage, there is a significant decrease by approximately 23 % in mean annual total groundwater withdrawals. During the study period, dramatic declines are found in agriculture-use groundwater pumpage in the downstream land of Chikugo river at the third stage, in industry-use pumpage in eastern Saga area at the second stage and found in waterworks-use pumpage in western Saga area at the last stage, while little change in agriculture-use pumpage in western Saga area and in industry-use pumpage in Chikugo area without the corresponding substitution projects. Moreover, it is indicated that the proposed assessment model of groundwater withdrawals is helpful to figure out the regional groundwater exploitation and its impact on the environment, particularly when there is the lack of groundwater pumpage data recorded. It is necessary to develop new substitute water supply plans to reduce the agriculture-use groundwater withdrawals in western Saga area and the industry-use withdrawals in Chikugo area, for more effective management of regional water resources in future.

Description: The aim of this study is to realize a distribution hydrological model to calculate the rainfall-runoff process precisely for the development of the ravine in the north Loess Plateau. On the basis of the real investigation result to the vertical profile of soil in the Liudaogou drainage basin, which is located in the ravine of wind-water erosion crisscross region in the northern Loess Plateau, a vertical profile model for soil in the study area was set up, and a distribution-type hydrological model was developed by combining GIS with kinematic wave theory. This model was subsequently applied in the experimental drainage basin. The numerical simulation results show that the calculation of the rainfall-runoff process has relatively high precision (error less than 3 %). The model was used to calculate the rainfall-runoff process for 5 years (2005–2009) in the experimental drainage basin to deduce the yearly surface runoff volume and the annual runoff coefficient. The calculated average runoff coefficient for 2005–2009 is 0.11, and the average 5 year precipitation (437 mm) is almost equal to the yearly average precipitation, indicating that the annual runoff coefficient of the experimental drainage basin is approximately 0.10 to 0.15. The study provides a practical numerical method for estimating surface water resources for the wind-water erosion crisscross region of the northern Loess Plateau.

Description: In this study, five different artificial intelligence methods, including Artificial Neural Networks based on Particle Swarm Optimization (PSO-ANN), Support Vector Regression (SVR), Multi- Layer Artificial Neural Networks (MLP), Radial Basis Neural Networks (RBNN) and Adaptive Network Based Fuzzy Inference System (ANFIS), were used to estimate monthly water level change in Lake Beysehir. By using different input combinations consisting of monthly Inflow - Lost flow (I), Precipitation (P), Evaporation (E) and Outflow (O), efforts were made to estimate the change in water level (L). Performance of models established was evaluated using root mean square error (RMSE), mean square error (MSE), mean absolute error (MAE) and coefficient of determination (R 2 ). According to the results of models, ε-SVR model was obtained as the most successful model to estimate monthly water level of Lake Beysehir.

Description: During dry years, such as 2003 and the early summer of 2011, the Netherlands faces water shortages, salt intrusion, navigation limitations and problems with availability of cooling water for power plants. Considering the changing climate, the frequency of these problems is expected to increase. A policy analysis using an integrated set of models has been launched by the government: the Dutch Delta Programme. The Delta model is the consistent set of models for analysing the decisions related to the long-term fresh water supply and flood risk management of the Netherlands. The country-wide SOBEK-1D hydrodynamic surface water model (LSM) was developed as part of the Delta model and forms the link between the Netherlands Hydrological Instrument (NHI) and impact assessment models for salinity, temperature, water quality, aquatic ecology and navigation. The Delta model provides a computational facility that automates the workflow of running sets of interconnected models for the national policy analysis on fresh water and various regional programmes within the Delta Programme. The Delta model, although being computationally demanding, enabled analyses of the present situation, future scenarios (2050 and 2100) and possible adaptation measures. Moreover, the Delta model has supported consistency between the national analyses and regional analyses in the Delta Programme.

Description: Fuzzy programming model has been widely used in water resources management, but its applicability has been significantly restricted in dealing with triangular or trapezoidal shaped fuzzy sets due to intrinsic complexity in converting fuzzy constraints into their deterministic forms. In this study, a novel superiority-inferiority-based sequential fuzzy programming (SISFP) model was proposed for supporting water supply–demand analysis under uncertainty. The SISFP method could transform fuzzy objective function and constraints with general-shaped fuzzy coefficients into their crisp equivalent by using fuzzy superiority and inferiority measures. The water supply–demand management system in Tianjin Binhai New Area, China, consisting of five sources of water, five water users at three districts (i.e. Tanggu, Hanggu, and Dagang), was used for methodology demonstration. The proposed model could effectively address the complex nature of fuzzy characterization of water-transfer safety factor, wastewater reclamation rate, the net benefits derived from water, and water-saving rate of the system; and also take demand management measures into consideration. The obtained solutions have sought a well balance among the water availability, water demand, adoption of water-saving measures, and benefit/cost of each water users. The advantage and necessity of SISFP in dealing with general-shaped fuzzy parameters were further verified by comparing to fuzzy models with both deterministic and specially-shaped fuzzy parameters.

Description: Accurate forecasting of rainfall is important in the effective management of water resources, particularly in arid regions. The wavelet analysis-support vector machine coupled model (WA-SVM) was evaluated for 1, 3 and 6 months ahead rainfall forecasting. The coupled model was obtained by combining the discrete wavelet transform (DWT) and support vector machine (SVM) methods. Monthly rainfall data from the Qilian, Yeniugou and Tuole stations in Qilian Mountains, China were used to optimize the model. By comparing the model output with the observed data on the basis of the coefficient of correlation (R), root mean squared error (RMSE), mean absolute error (MAE) and Nash-Sutcliffe efficiency coefficient (NS), it was found that the performances of WA-SVM models for 1, 3 and 6-month ahead rainfall forecasting were good, and the models have forecasted the rainfall values with reasonable accuracy in all the statistical indices during testing period. Relative to the performance of regular SVM models, we show that the WA-SVM model demonstrates superior accuracy among the SVM models in forecasting rainfall at all tested lead times, probably due to a wavelet transform effect on the SVM predictive ability. The WA-SVM model was also compared with conventional ANN models, and the WA-SVM model was found to be significantly superior. The results of the study indicate that the WA-SVM model is preferable and can be applied successfully because it provides high accuracy and reliability for multi-time ahead monthly rainfall forecasting.

Description: The Wei River Basin, a typical arid and semi-arid region, is frequently attacked by droughts, which heavily limits its sustainable development of society and economy. Therefore, the main motivation of this study is to investigate the drought evolution characteristics and risk evaluation in the basin, which is crucial for drought warning, water resources management as well as agricultural development. The modified Mann-Kendall test trend method was used to capture the trend of the severity and duration of historical drought events, and the persistence of droughts was analyzed based on the Rescaled Range (R/S) analysis. Additionally, the Morlet wavelet analysis was utilized to calculate the period of dry and wet condition, and copulas were applied to calculate the joint return period of two typical scenarios. The main results are as follows: (1) the whole basin has an obviously dry trend, especially in autumn and winter; furthermore, the months with a wet trend are primarily concentrated in July and August; (2) the persistence of droughts is strong, indicating that droughts in the near future may be persistent; (3) the average “or” and “and” joint return periods under scenario (1) where drought duration is 6 months and drought severity is 4 are approximately 15.6 and 28.9 years, respectively, while those under scenario (2) where drought duration is 8 months and drought severity is 6 are approximately 34.9 and 53.1 years, respectively. In general, the drought risk of the northwestern basin is larger than that of the southeastern basin.

Description: In reservoir flood control operation, the safety of upstream and downstream of the dam are the main two optimization goals with conflicts. In addition, the irrigation water demands is also an important issue considered by decision makers. Therefore, the dispatching schemes that meet the final water level constraint are preferred. Considering such preference in decision making, a novel preference-based selection operator is developed and combined with immune inspired optimization technique to form the proposed multi-objective immune algorithm with preference- based selection (MOIA-PS) for reservoir flood control operation. The unique of MOIA-PS is that it intends to obtain a set of preferred Pareto optimal solutions that located within a part of preferred area on the Pareto front rather than to find a good approximation of the entire Pareto front as most existing methods did. Experimental results on four typical floods at the Ankang reservoir have indicated that the preferred non-dominated solutions are distributed within a local area of preferred PF region. And the newly designed preference-based selection operator can guide the search of MOIA-PS towards the preferred PF region. Comparing with the outstanding multi-objective evolutionary algorithm NSGAII and the immune inspired multi-objective optimization algorithm NNIA, the proposed MOIA-PS obtains more non-dominated solutions that densely and evenly scattered within the preferred area of the Pareto front. MOIA-PS can find finding dispatching schemes that not only reduce the flood peak significantly and guarantee the dam safety well but also satisfy the irrigation water demands. It is a more efficient use of the computing efforts.

Description: Climate change projections predict a rise in temperatures which may result in a reduction in water resource availability. Irrigation is both the most demanding water use and that which is the lowest priority. Consequently, adaptation measures regarding irrigation demands are required in coping with such a resource decrease. As improvement in water efficiency use could not be enough to counteract strong stream flow reductions, management actions regarding demands may be implemented. This paper proposes a methodology for identifying the required reductions and sequence in which water allocation is to be reduced in order to meet satisfactory system behaviour. Such a methodology could help basin managers in decision making in meeting irrigation demands which, accordingly, could offer better performance in terms of both reliability and productivity. The methodology is applied at the Guadalquivir Basin in Spain, under eight hydrological projections which represent future climate change scenarios. The results show that it is possible to reduce future water scarcity problems and, hence, improve system performance. In addition to this, it is found that optimal reduction sequence is not only affected by water productivity, but also by the system topology which influences reliability. In the case study, the most sensitive demands are those located at the river head. As such demands have no alternative sources, they typically offer the lowest degree of reliability.

Description: Groundwater economic models have refined optimal extraction rules while lagging behind in the study of optimal spatial policies. This paper develops a theoretical model to estimate welfare gains from optimal groundwater management when the choice variable set is expanded to include well location decisions as well as optimal groundwater extraction paths. Our theoretical results show that if there is spatial heterogeneity in groundwater, the welfare gains from optimal location of wells are substantial even if extraction rates are unregulated. Furthermore, second-best economically defined spacing regulations may possibly have better efficiency results (and lower implementation costs) than first-best uniform taxes or quotas. An application of the model to a real-world aquifer shows the importance of including well location decisions in spatially differentiated groundwater models and the need for (1) robust estimates of the gains from optimal management and; (2) spatially explicit regulations.

Description: The potential effects of mid-21st century climate change on the hydrology of the Cook Inlet watershed in south-central Alaska was analyzed in this study. Climate datasets representing a set of potential change scenarios for the period 2041–2070 were developed from the North American Regional Climate Change Assessment Program (NARCCAP) archive of dynamically downscaled climate products. The NARCCAP 50-km scale regional climate output was converted to realistic daily weather time series using a “change factor” method in which observed meteorological time series used for model calibration are perturbed. The perturbations are based on statistical summaries of change for the different climate scenarios, by month, as calculated from the differences between the 1971–2000 and 2040–2070 climate model simulation periods. The downscaled climate datasets were then used to run the Soil and Water Assessment Tool (SWAT) for the Cook Inlet watershed. Generally, it was observed that increasing rainfall and warmer temperatures across the Cook Inlet watershed led to a predicted increase in the stream flow in the major rivers, increase in 7-day low flows, and considerable increase in 100-year peak flow. Furthermore, under future climatic conditions precipitation is expected to increase in the Cook Inlet watershed but the amount of snowfall is expected to decrease. Also, the amount of snowmelt is expected to increase due to warmer temperature thereby causing the average annual fraction of snowfall as precipitation to decrease leading to a reduction in the glacial mass balance in the watershed. Moreover, average annual water yield, runoff, baseflow, snowmelt across the basin is expected to increase. More specifically the different hydrologic components varied seasonally and monthly driven by the seasonal and monthly changes in precipitation and temperature. However, the overall hydrology of the watershed is projected to remain snowmelt dominated through the mid-21st century without a major shift in regime. These simulations provide a benchmark of hydrologic sensitivity to potential future climate change in this watershed useful for identifying vulnerabilities and informing the development of adaptation responses.