Spatiotemporal Modelling of Water Balance Components in Response to Climate and Landuse Changes in a Heterogeneous Mountainous Catchment

Landuse change and climate change are the main drivers of hydrological processes. The purpose of this study was to analyse the separate and combined future effects of climate and landuse changes on water balance components on different spatial and temporal scales using the integrated hydrological Soil and Water Assessment Tool model. The study focused on the changes and relationship between water yield (WYLD) and sediment yield (SYLD) in the heterogeneous Taleghan Catchment in Iran. For future climate scenarios, RCP 4.5 and RCP 8.5 of GFDL-ESM2M GCM were used for 2020–2040. A Markov chain model was used to predict landuse change in the catchment. The results indicated an increase in precipitation and evapotranspiration. The findings also showed that the relationship between WYLD and SYLD is direct and synergic. Climate change has a stronger effect on WYLD than landuse change, whereas landuse change has a stronger effect on SYLD. The conversion of rangelands to barren land is the most critical landuse change that could increase SYLD. The highest increase in WYLD and SYLD in scenario RCP4.5 resulted from the combined effects of climate and landuse change. We estimated WYLD of about 295 mm and SYLD of around 17 t/ha. The proposed methodology is universal and can be applied to similar settings to identify the most vulnerable regions. This can help prioritize management strategies to improve water and soil management in watersheds.

     

Advanced Evaluation Methodology for Water Quality Assessment Using Artificial Neural Network Approach

Water Resources Management - The increasing rate of water pollution and consequent increase of waterborne diseases are compelling evidence of danger to public health and all living organisms....     

Groundwater Modeling Under Variable Operating Conditions Using SWAT,MODFLOW and MT3DMS: a Catchment Scale Approach to Water Resources Management

This paper presents an integrated modeling approach by linking soil and water application tool (SWAT), modular finite difference groundwater flow (MODFLOW) and modular 3-dimensional multi-species transport (MT3DMS) models capable of predicting a groundwater system response, in terms of flow and salt concentrations, to current and future development conditions. SWAT, a semi-distributed hydrologic model, estimates the spatio-temporal distribution of groundwater recharge rates. These rates are then input to MODFLOW using an interface module developed that maps the HRU-based spatial resolution of SWAT outflows into the cell-based spatial structure of inputs to MODFLOW and MT3DMS. The integrated SWAT-MODFLOW-MT3DMS model is used in modeling Dehloran aquifer system located in the arid western region of Iran, experiencing changes in land-use, irrigation system and pumping locations and loads. The results illustrate the significance of the developed integrated modeling tool in quantifying the impact of changes in land and surface water resources on its subsurface water system.     

Groundwater Recharge Assessment for the Kalahari Catchment of North-eastern Namibia and North-western Botswana with a Regional-scale Water Balance Model

Groundwater is the only source of drinking water for the inhabitants of the Kalahari. Thus understanding spatial and temporal variations in groundwater recharge is very important and a regional-scale water balance model has therefore been set up for a 209,149 km² catchment in north-eastern Namibia and north-western Botswana. The model has a spatial resolution of 1.5 × 1.5 km, daily model time-steps, and climatic input parameters for 19 years are used. The distributed, GIS-based, process-oriented, physical water balance model (MODBIL) used in this study considers the major water balance components: precipitation, evapotranspiration, groundwater recharge, and surface runoff/interflow. Mean precipitation for the study area is 409 mm a⁻¹, while mean actual evapotranspiration is 402 mm a⁻¹ and mean groundwater recharge is 8 mm a⁻¹ (2% of mean annual precipitation). The recharge pattern is mainly influenced by the distribution of soil and vegetation units. Groundwater recharge shows a high inter- and intra-annual variability, but not only the sum of annual precipitation is important for the development of groundwater recharge; a large amount of precipitation in a relatively short period is more important. Published independent data from the Kalahari in Namibia, Botswana and the Southern African region under similar climatic conditions are used to verify the modelling results.     

A Modified SEBAL Modeling Approach for Estimating Crop Evapotranspiration in Semi-arid Conditions

Remote sensing methods are becoming attractive to estimate crop evapotranspiration, as they cover large areas and can provide accurate and reliable estimations; intensive field monitoring is also not required, although some ground-truth measurements can be helpful in interpreting satellite images. For the purposes of this paper, modeling and remote sensing techniques were integrated for estimating actual evapotranspiration of groundnuts (Arachishypogaea, L.) that is cultivated near Mandria Village in Paphos District of Cyprus. The Surface Energy Balance Algorithm for Land (SEBAL) was adopted for the first time in Cyprus, employing the essential adaptations for local soil and meteorological conditions. Landsat-5 TM and 7 ETM+ images were used to retrieve the needed spectral data. The SEBAL model is enhanced with empirical equations determined as part of the present study, regarding crop canopy factors, in order to increase its accuracy. Maps of ET_a were created using the SEBAL modified model (CYSEBAL) for the area of interest. The results have been compared to the measurements from an evaporation pan (which was used as a reference) and those of the original SEBAL model. The statistical comparison has shown that the modified SEBAL yields results that are comparable to those of the evaporation pan. T-test application has revealed that the statistical difference between SEBAL and CYSEBAL is significant and quite crucial, especially in a place with limited surface and underground water resources.     

Hydrologic Analysis of Rainfed Rice Areas Using a Simple Semi-distributed Water Balance Model

We analyzed the hydrologic characteristics of the Nong Saeng Basin (19.72 km²) in northeast Thailand. Because the land use in this basin is very complex, applying a fully distributed model would be extremely difficult. Therefore, we developed a semi-distributed hydrologic model for this basin. The hydrologic model comprised upland, paddy, and pond models. The new bucket model was applied for upland fields, and a modified tank model was used for the paddy and pond models. In addition, water movement between different land uses was considered. The results showed that the hydrologic model developed for the study basin performed extremely well if water movement between different land uses was considered. We simulated the water storage characteristics for two sub-catchments within the basin: sub-catchment 1 included few earthen weirs, whereas sub-catchment 2 included several earthen weirs. Owing to the earthen weirs, the maximum differences in ponding paddy water were 19,997 m³ in 2002 and 16,897 m³ in 2003, corresponding to 48% and 41% of the total volume of ponds in sub-catchment 1 (41,287 m³), respectively. If earthen weirs were to be constructed over the entire basin, the annual runoff from the basin would decrease by 2.0–3.2%. Although the decrease of the annual runoff is little, the maximum differences between the daily runoffs under real and simulated conditions in terms of percentage differences are −44.3% in September 2002 and −36.5% in September 2003, and it is found that the downstream impacts are quite large at the end of rainy season.     

Water Costs Allocation in Complex Systems Using a Cooperative Game Theory Approach

The management of complex water resource systems that address water service recovery costs and consider adequate contributions and priorities require methods that integrate technical, economic, environmental, social and legal aspects into a comprehensive framework. In Europe, the Water Framework Directive (WFD) 2000/60/EC recommends that the pricing politics in a river basin take into account the cost recovery and the economic sustainability of the water use. However, the current cost allocation methods do not consider the user’s willingness to pay and often do not permit a total cost recovery. Thus, a new approach is required that includes these requirements when defining water rates. This article presents a methodology to allocate water service costs in a water resource system among different users that attempts to fulfil the WFD requirements. The methodology is based on Cooperative Game Theory (CGT) techniques and on the definition of the related characteristic function using a mathematical optimisation approach. The CGT provides the instruments that are necessary to analyse situations that require a cost-sharing rule. The CGT approach can define efficient and fair solutions that provide the appropriate incentives among the parties involved. Therefore, the water system cost allocation has been valued as a game in which it is necessary to determine the right payoff for each player that is, in this case, a water user. To apply the CGT principles in a water resources system, the characteristic function needs to be defined and evaluated using an adequate modelling approach; in this study, it is evaluated using the optimisation model WARGI. (Sechi and Zuddas 2000). The so-called “core” represents the game-solution set. It represents the area of the admissible cost allocation values from which the boundaries on the cost values for each player can be supplied. Within the core lie all of the allocations that satisfy the principles of equity, fairness, justice, efficiency and that guarantee cost recovery. The core of a cooperative game can represent a useful instrument to define the water cost rates. Furthermore, it can be used as a valid support in water resource management to achieve the economic analysis required by the WFD. The methodology was applied to a multi-reservoir and multi-demand water system in Sardinia, Italy.     

泥沙冲淤模型在汾河流域上游的应用

文中通过对张启舜等人开发研制的“河流与水库冲淤计算模型”在汾河流域上游的应用，确定出不同水平年各调节水库的库容及纵向淤积形态，为汾河水库坝前取水口进水塔设计提供了依据。     

Dynamic Water Balance Accounting-Based Vulnerability Evaluation Considering Social Aspects

Water Resources Management - To advance proper planning, water accounting (WA) could provide the possibility of linking physical and operational data to their interdisciplinary attributes. In its...     

吉林市水资源供需平衡途径探讨

本文根据吉林市水资源开发利用的现状,从水资源管理体制、水资源的高效水量评价和建立节水型社会三方面,探讨了解决吉林市水资源供需平衡和可持续利用的途径,以期为支撑吉林经济社会可持续发展的水资源供需平衡途径研究提供借鉴和参考。     

Catchment Phosphorous Losses: An Export Coefficient Modelling Approach with Scenario Analysis for Water Management

This paper presents the development of an export coefficient model to characterise the rates and sources of P export from land to water in four reservoir systems located in a semi-arid rural region in southern of Portugal. The model was developed to enable effective management of these important water resource systems under the EU Water Framework Directive. This is the first time such an approach has been fully adapted for the semi-arid systems typical of Mediterranean Europe. The sources of P loading delivered to each reservoir from its catchment were determined and scenario analysis was undertaken to predict the likely impact of catchment management strategies on the scale of rate of P loading delivered to each water body from its catchment. The results indicate the importance of farming and sewage treatment works/collective septic tanks discharges as the main contributors to the total diffuse and point source P loading delivered to the reservoirs, respectively. A reduction in the total P loading for all study areas would require control of farming practices and more efficient removal of P from human wastes prior to discharge to surface waters. The scenario analysis indicates a strategy based solely on reducing the agricultural P surplus may result in only a slow improvement in water quality, which would be unlikely to support the generation of good ecological status in reservoirs. The model application indicates that a reduction of P-inputs to the reservoirs should first focus on reducing P loading from sewage effluent discharges through the introduction of tertiary treatment (P-stripping) in all major residential areas. The fully calibrated export coefficient modelling approach transferred well to semi-arid regions, with the only significant limitation being the availability of suitable input data to drive the model. Further studies using this approach in semi-arid catchments are now needed to increase the knowledge of nutrient export behaviours in semi-arid regions.     

Optimization of Irrigation Scheduling Using Soil Water Balance and Genetic Algorithms

In arid and semi-arid countries, the use of irrigation is essential to ensure agricultural production. Irrigation water use is expected to increase in the near future due to several factors such as the growing demand of food and biofuel under a probable climate change scenario. For this reason, the improvement of irrigation water use efficiency has been one of the main drivers of the upgrading process of irrigation systems in countries like Spain, where irrigation water use is around 70 % of its total water use. Pressurized networks have replaced the obsolete open-channel distribution systems and on farm irrigation systems have been also upgraded incorporating more efficient water emitters like drippers or sprinklers. Although pressurized networks have significant energy requirements, increasing operational costs. In these circumstances farmers may be unable to afford such expense if their production is devoted to low-value crops. Thus, in this work, a new approach of sustainable management of pressurized irrigation networks has been developed using multiobjective genetic algorithms. The model establishes the optimal sectoring operation during the irrigation season that maximize farmer’s profit and minimize energy cost at the pumping station whilst satisfying water demand of crops at hydrant level taking into account the soil water balance at farm scale. This methodology has been applied to a real irrigation network in Southern Spain. The results show that it is possible to reduce energy cost and improve water use efficiency simultaneously by a comprehensive irrigation management leading, in the studied case, to energy cost savings close to 15 % without significant reduction of crop yield.     

关于粤北山区局部地区地表水资源量评价分析

地表水资源是一种不可替代性资源,始终是人们关注的焦点问题.为充分摸清粤北山区局部地区地表水资源现状情况,奠定地区经济可持续发展的坚实基础和信心,现从径流时空分布情况切入,探讨粤北山区阳山县多年径流时空分布极不均匀的特征;利用倒算法分析阳山县地表水资源量可利用情况.结果表明,粤北山区主要河流水资源情况良好,水资源可利用量...     

Location and Calibration of Valves in Water Distribution Networks Using a Scatter-Search Meta-heuristic Approach

Recently, there has been an increase in the use of meta-heuristic techniques addressing water distribution network design and management optimization problems. The meta-heuristic approach applied to water distribution systems has provided interesting results both for optimum pipe diameter sizing and for the location and management of network pressure control devices (i.e., pumps and valves). Regarding the insertion and calibration of pressure regulation valves, the use of meta-heuristic techniques is relatively recent. We search to strategically placing the valves in order to achieve pressure control in the network and, therefore, the valves must be calibrated in relation to water demand trends over time. In the Pressure Reference Method (PRM) described in this paper, the search for valve location is restricted to pipe-branch sets defined on the basis of hydraulic analysis and considering the range between minimum and maximum acceptable pressures in the network. In the PRM approach, the Scatter-Search (Glover and Laguna, 1997) meta-heuristic procedures are applied to obtain the optimal location and calibration of valves in the water distribution network.     

Catchment Erosion and Sediment Delivery in a Limno-Reservoir Basin Using a Simple Methodology

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 km²), 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.     

A Daily Water Balance Modelling Approach for Simulating Performance of Tank-Based Irrigation Systems

Tanks are small reservoirs, which are widely distributed in South India and Sri Lanka, where they represent an important water resource for people, crops, livestock and fish. Considerable efforts have been made to rehabilitate tank irrigation systems in recent decades, but there have been few studies carried out to improve understanding of their hydrology. This paper presents a daily water balance approach, which aims to simulate the dynamic behaviour of tank storage. The model was validated over four seasons for two representative tanks within Mahaweli System H, a major irrigation system in the dry zone of Sri Lanka. Use of the model to evaluate current performance and scope for improvement is demonstrated.     

Pareto Optimization of Water Resources Using the Nexus Approach

The continuously growing population in combination with the escalating urbanization and economic growth increase the pressure on water, energy and food resources of our planet. This entails an urgent need for proper water resources management within the water-energy-food (WEF) nexus concept. The WEF nexus considers water, energy and food as three continuously interconnected sectors, whose complex interactions lead to an increased number of trade-offs and potential conflicts. Computational modeling can be used to quantify these interactions, reduce trade-offs and promote synergies. We investigate the water resources in the Upper Blue Nile River (UBNR) basin, one of the two main sources of the Nile, using the Hydronomeas tool. Hydronomeas is based on the parameterization-simulation-optimization method; optimization is implemented in two levels, using a holistic approach and multiple criteria. We assign various targets, constraints and priorities to the UBNR system of reservoirs, hydropower plants and irrigation projects and derive a Pareto front that contains alternative, optimal solutions, for which improvement of one objective can be achieved only at the expense of another. By visualizing the trade-offs between the conflicting objectives of hydropower and irrigation, we aim to help decision makers understand changes due to different management policies and thus, achieve greater efficiency in water resources management in the Nile region.     

Catchment Storage and its Influence on Summer Low Flows in Central European Mountainous Catchments

The objective of this study was to determine the role of spring catchment water storage on the evolution of low flows in central European mountainous catchments. The study analysed 58 catchments for which catchment storage, represented by snow, soil water and groundwater storages, was determined by the HBV hydrological model over a 35-year period. The spring catchment storage was related to several streamflow indices describing low flow periods using the mutual information criterion. The mean runoff in the summer and autumn periods was mostly related to rainfall sums from the respective season. The median relative contribution of rainfall to the total mutual information value was 48.4% in summer, and 44.2% in autumn period, respectively. The relative contribution of soil water and groundwater storages was approximately 25% for each of the components. In contrast, the minimum runoff, its duration and deficit runoff volume, were equally related to both catchment storage and seasonal rainfall, especially in the autumn period.

     

水质综合评价方法探讨

水质综合评价实质上属于模式识别问题。就目前运用较多的三种水质综合评价方法,即模糊模式识别法、灰关联模式识别法、BP人工神经网络法,采用MATLAB语言编写相应的评价程序进行实例评价,试图找出三种方法在水质综合评价中的优缺点。从总体评价结果可以看出,模糊模式识别法评价结果偏高,灰关联模式识别法评价结果偏低,BP人工神经网络法评价结果比较准确。