Effect of Hedging-Integrated Rule Curves on the Performance of the Pong Reservoir (India) During Scenario-Neutral Climate Change Perturbations

This study has evaluated the effects of improved, hedging-integrated reservoir rule curves on the current and climate-change-perturbed future performances of the Pong reservoir, India. The Pong reservoir was formed by impounding the snow- and glacial-dominated Beas River in Himachal Pradesh. Simulated historic and climate-change runoff series by the HYSIM rainfall-runoff model formed the basis of the analysis. The climate perturbations used delta changes in temperature (from 0° to +2 °C) and rainfall (from ?10 to +10 % of annual rainfall). Reservoir simulations were then carried out, forced with the simulated runoff scenarios, guided by rule curves derived by a coupled sequent peak algorithm and genetic algorithms optimiser. Reservoir performance was summarised in terms of reliability, resilience, vulnerability and sustainability. The results show that the historic vulnerability reduced from 61 % (no hedging) to 20 % (with hedging), i.e., better than the 25 % vulnerability often assumed tolerable for most water consumers. Climate change perturbations in the rainfall produced the expected outcomes for the runoff, with higher rainfall resulting in more runoff inflow and vice-versa. Reduced runoff caused the vulnerability to worsen to 66 % without hedging; this was improved to 26 % with hedging. The fact that improved operational practices involving hedging can effectively eliminate the impacts of water shortage caused by climate change is a significant outcome of this study.     

Multi-Objective Optimization of the Proposed Multi-Reservoir Operating Policy Using Improved NSPSO

Severe water shortage is unacceptable for water-supply reservoir operation. For avoiding single periods of catastrophic water shortage, this paper proposes a multi-reservoir operating policy for water supply by combining parametric rule with hedging rule. In this method, the roles of parametric rule and hedging rule can be played at the same time, which are reducing the number of decision variables and adopting an active reduction of water supply during droughts in advance. In order to maintain the diversity of the non-dominated solutions for multi-objective optimization problem and make them get closer to the optimal trade-off surfaces, the multi-population mechanism is incorporated into the non-dominated sorting particle swarm optimization (NSPSO) algorithm in this study to develop an improved NSPSO algorithm (I-NSPSO). The performance of the I-NSPSO on two benchmark test functions shows that it has a good ability in finding the Pareto optimal set. The water-supply multi-reservoir system located at Taize River basin in China is employed as a case study to verify the effect of the proposed operating policy and the efficiency of the I-NSPSO. The operation results indicate that the proposed operating policy is suitable to handle the multi-reservoir operation problem, especially for the periods of droughts. And the I-NSPSO also shows a good performance in multi-objective optimization of the proposed operating policy.     

Optimizing Reservoir Operation Policy Using Chance Constraint Nonlinear Programming for Koga Irrigation Dam,Ethiopia

One of typical problems in water resources system modeling is derivation of optimal operating policy for reservoir to ensure water is used more efficiently. This paper introduces optimization analysis to determine monthly reservoir operating policies for five scenarios of predetermined cropping patterns for Koga irrigation scheme, Ethiopia. The objective function of the model was set to minimize the sum of squared deviation (SSD) from the desired targeted supply. Reservoir operation under different water availability and thresholds of irrigation demands has been analyzed by running a chance constraint nonlinear programming model based on uncertain inflow data. The model was optimized using Microsoft Excel Solver. The lowest SSD and vulnerability, and the highest volumetric reliability were gained at irrigation deficit thresholds of 20 % under scenario I, 30 % under scenario II, III and V, and at 40 % under scenario IV when compensation release is permitted for downstream environment. These thresholds of deficits could be reduced by 10 % for all scenarios if compensation release is not permitted. In conclusion the reservoir water is not sufficient enough to meet 100 % irrigation demand for design command areas of 7,000 ha. The developed model could be used for real time reservoir operation decision making for similar reservoir irrigation systems. In this specific case study system, attempt should be made to evaluate the technical performance of the scheme and introduce a regulated deficit irrigation application.     

Modelling Intelligent Water Resources Allocation for Multi-users

This study proposes intelligent water resources allocation strategies for multiple users through hybrid artificial intelligence techniques implemented for reservoir operation optimization and water shortage rate estimation. A two-fold scheme is developed for (1) knowledge acquisition through searching input–output patterns of optimal reservoir operation by optimization methods and (2) the inference system through mapping the current input pattern to estimate the water shortage rate by artificial neural networks (ANNs). The Shihmen Reservoir in northern Taiwan is the study case. We first design nine possible water demand conditions by investigating the changes in historical water supply. With the nine designed conditions and 44-year historical 10-day reservoir inflow data collected during the growth season (3 months) of the first paddy crop, we first conduct the optimization search of reservoir operation by using the non-dominated sorting genetic algorithm-II (NSGA-II) in consideration of agricultural and public water demands simultaneously. The simulation method is used as a comparative model to the NSGA-II. Results demonstrate that the NSGA-II can suitably search the optimal water allocation series and obtain much lower seasonal water shortage rates than those of the simulation method. Then seasonal water shortage rates in response to future water demands for both sectors are estimated by using the adaptive network fuzzy inference system (ANFIS). The back-propagation neural network (BPNN) is adopted as a comparative model to the ANFIS. During model construction, future water demands, predicted monthly inflows (or seasonal inflow) of the reservoir in the next coming quarter and historical initial reservoir storages configure the input patterns while the optimal seasonal water shortage rates obtained from the NSGA-II serve as output targets (training targets) for both neural networks. Results indicate that the ANFIS and the BPNN models produce almost equally good performance in estimating water shortage rates, yet the ANFIS model produces even better stability. The reliability of the proposed scheme is further examined by scenario analysis. The scenario analysis indicates that an increase in public water demand or a decrease in agricultural water demand would bring more impacts of water supply on agricultural sectors than public sectors. Similarly, a bigger decrease in inflow amount would obviously bring more influence on agricultural sectors than public one. Consequently, given predicted inflow, decision makers can pre-experience the possible outcomes in response to competing water demands through the estimation models in order to determine adequate water supply as well as preparedness measures, if needed, for drought mitigation.     

Optimization of Hedging Rules for Reservoir Operation During Droughts Based on Particle Swarm Optimization

This paper presents a methodology to achieve the identification of optimal hedging rules for operating reservoir systems, seeking to mitigate the drought impacts. The heuristic Particle Swarm Optimization (PSO) method is adopted as the optimization solver. This procedure establishes a two-phase method that combines PSO with the simulation of the water system, representing a system of reservoirs that are jointly operated to satisfy a set of demands with different priorities. The hedging rules are based on monthly storage levels that trigger restrictions on the demands. As model parameters, monthly rule activation thresholds and rationing factors were used for each type of demand. The optimization procedure minimizes an objective function that penalizes large deficits and assigns different weights to different demand types. Since the whole problem is quite complex, its dimensionality is reduced through: i) a set of candidate monthly activation thresholds are selected a priori associated to given risk conditions; and ii) the rationing factors are defined for every demand of each threshold throughout all months. In addition, an effort is made to avoid the trap in local optimums, whilst several other comments considering the application of the PSO method in the examined applications are provided. The procedure has been successfully applied to four water resource systems in Spain. From the application it can be seen that the deficits of the water supply demand are nearly removed, thanks to the larger weight given to the deficits of this demand type. The irrigation deficits are also reduced, since we lead to a sequence of smaller shortages than only one potential catastrophic shortage.     

黄三角高效生态经济区城市水资源需求预测

黄河三角洲特殊的地理条件使得该地区水资源严重匮乏,已成为制约该地区社会经济发展的瓶颈。在对黄河三角洲高效生态经济区经济发展和水资源现状分析的基础上,分趋势分析(情景1)和规划目标(情景2)两种情景模式,从生活、工业和生态三方面预测和分析三角洲城市需水量。结果表明:在情景1条件下,规划年2015年和2020年城市综合需水量将分别达7.43亿、9.57亿m3,分别为2009年的1.49和1.92倍;在情景2条件下,2015年和2020年城市综合需水量将分别达9.49亿、11.71亿m3,分别为2009年的1.91和2.35倍。建议综合开发利用水资源,增强居民节水意识,推动节水技术在工业生产中的应用,加紧城市污水处理厂和中水回用设施建设,在保证城市污水处理厂出水水质的条件下,提高城市中水回用率,实现城市水资源长期、有效、可持续利用。     

Derivation of Optimal Hedging Rules for a Water-supply Reservoir through Compromise Programming

This study derives optimal hedging rules for simultaneously minimizing short- and long-term shortage characteristics for a water-supply reservoir. Hedging is an effective measure to reduce a high-percentage single period shortage, but at a cost of more frequent small shortages. Thus simultaneously minimizing the maximum monthly shortage and the shortage ratio (defined as the ratio of total shortages to total demands) over the analysis horizon is the operation goal of a water-supply reservoir to derive optimal hedging rules. Two types of hedging are explored in this study: the first uses water availability defined as storage plus inflow, while the second depends on the potential shortage conditions within a specific future lead-time period. The compromise programming is employed to solve this conflicting multiobjective problem. The optimal hedging rules under given reservoir inflow are derived first. Because future inflow cannot be known exactly in advance, the monthly decile inflows are suggested as a surrogate for forecast of future inflows in hedging rules for real-time reservoir operations. The results show that the suggested method can effectively achieve the reservoir operation goal. The merits of the proposed methodology are demonstrated with an application to the Shihmen reservoir in Taiwan.     

Analysis and Modelling of Stormwater Volume Control Performance of Rainwater Harvesting Systems in Four Climatic Zones of China

Rainwater harvesting has been widely used to alleviate urban water scarcity and waterlogging problems. In this study, a water balance model is developed to continuously simulate the long-term (57 to 65 years) stormwater capture efficiency of rainwater harvesting systems for three water demand scenarios at four cities across four climatic zones of China. The impacts of the “yield after spillage” (YAS) and “yield before spillage” (YBS) operating algorithms, climatic conditions, and storage and demand fractions on stormwater capture efficiency of rainwater harvesting systems are analyzed. The YAS algorithm, compared with the YBS, results in more conservative estimations of stormwater capture efficiency of rainwater harvesting systems with relatively small storage tanks (e.g., ≤50 m³). The difference between stormwater capture efficiency calculated using the YBS and YAS algorithms can be remedied by increasing storage capacity and reduced by decreasing water demand rates. Higher stormwater capture efficiency can be achieved for rainwater harvesting systems with higher storage and demand fractions and located in regions with less rainfall. However, the lager variations in annual rainfall in arid zones may lead to unstable stormwater management performance of rainwater harvesting systems. The impacts of storage and demand fractions on stormwater capture efficiency of rainwater harvesting systems are interactive and dependent on climatic conditions. Based on the relationships among storage capacity, contributing area, water demand, and stormwater capture efficiency of rainwater harvesting systems, easy-to-use equations are proposed for the hydrologic design of rainwater harvesting systems to meet specific stormwater control requirements at the four cities.     

基于GWAS模型的武安市水资源优化配置

为缓解河北武安市水资源供需不平衡的突出矛盾,立足水资源精细化管理的需求,构建了武安市GWAS(general water allocation and simulation )模型,并开展规划年(2025年与2030年)不同情景下武安市各乡镇水资源优化配置研究。结果表明:2025年和2030年,平水情景(P=50%)下模型优化配置水量基本可以满足各乡镇水量需求,枯水情景(P=75%)下各乡镇存在不同程度的缺水情况;全市普遍农业缺水,2025年平枯情景农业缺水率分别为6.45%和44.11%,2030年平枯情景农业缺水率分别为5.05%和42.47%;优化后的供水结构改善效果显著,地下水供水量占比在各规划年平枯情景下均有所下降。     

黄淮海流域片种植结构变化对灌溉需水的影响与预测分析

中国面临的水危机表现之一为黄淮海流域片的灌溉用水危机。减少流域片高耗水作物种植,调整农业产业结构被认为是解决灌溉水危机的重要手段。本文分析了未来黄淮海流域片种植结构变化对区域灌溉需水的影响。结果表明,如果不采取提高灌溉水价等新的灌溉用水政策,流域片播种面积在全国总播种面积下降的情况下还会增加。种植结构调整引起流域片灌溉需水总量增长而不是减少。如果没有新的水资源管理办法,减少黄淮海流域片高耗水作物种植的政策可能会难以落到实处。     

Evaluation and selection of hedging policies using stochastic reservoir simulation

A hedging policy is characterized by three parameters, namely, starting water availability (SWA), ending water availability (EWA) and hedging factor (HF). The effects of these three parameters on the reservoir performance indicators have been evaluated and discussed for a southwest monsoon-dependent within-year reservoir system in southern India. For the performance evaluation, synthetically generated periodic inflow sequences from a periodic autoregressive model have been used. Quite a number of the 1800 hedging policies considered for the reservoir system, yield a better overall performance compared to the standard operating policy (SOP). Reliability, Resilience and vulnerability are found to increase with SWA for a specified EWA. On the other hand, all these performance indicators are found to decrease with EWA for a specified SWA. Hence, it is desirable to start the hedging at reasonably high SWA. All performance indicators remain practically constant at higher ranges of EWA for a given SWA. If hedging is started when there is enough water in storage, reliability, resilience and average deficit increase with degree of hedging, whereas vulnerability decreases significantly up to a hedging factor of 0.3. An interactive computer program has been developed for the selection of compromising hedging policies, and its usefulness has been discussed.     

气候变化和人类活动影响下北京市需水量预测

气候变化和人类活动是影响陆面水文循环过程及水资源供需平衡最重要的两大驱动因素。采用综合、系统的方法构建了北京市需水量预测模型,并考虑了诸多因素及其相互关系,对不同用水部门的需水量进行了计算。结果表明:①2019～2030年期间,北京市总需水量将至少增长15.1%(最多增长33.8%),相应的缺水量为3.94亿～19.22亿m~3;②气候变化将在很大程度上影响北京市的水平衡,跨流域调水和水资源保护技术在缓解水资源短缺方面发挥着重要的作用;③鉴于模型采用的需水量计算方法具有普遍性、情景设计和分析过程具有可移植性,所建立的SD模型可以推广至其他特大城市进行需水量的预测及分析。     

北三河流域水资源供需平衡对降水变化的敏感性

分析不同区域水资源供需平衡对降水变化的敏感性,并结合考虑云水资源和降水效率的空间分布,有助于常态化人工增雨作业地点的确定,对实现空陆水资源的统筹利用具有重要意义。以北三河流域为研究区域,基于新安江模型和彭曼-蒙特斯公式分析了研究区需水量对降水变化的响应,并探讨了不同计算单元水资源供需平衡对降水变化的敏感性。结果表明:当降水量增加时,流域平水年产水量增加的比例大于枯水年与特枯年,农田灌溉需水量随降水量的增加大致呈线性减小趋势;在不考虑外调水和地下水超采的情况下,自然降水情景的流域资源性缺水量分别为35.46亿m3（降水频率p=50%）、43.17亿m3（p=75%）和46.30亿m3（p=95%）,缺水峰值分别出现在5月、7月和8月;各单元缺水量对降水变化的敏感性主要由产水变化主导,空间上呈由北向南逐渐递减的趋势,当平水年降水量增加20%时,北部地区缺水量相对减少率达到150%以上,中部介于30%~50%,南部则小于15%。     

基于宽浅式破坏原则的水库旱限水位优化方法EI北大核心CSCD

针对旱限水位计算过程中干旱期需水多采用经验性调整系数确定存在主观性较强、合理性不足等问题,基于宽浅式破坏原则,以枯水年内月缺水率均值及其标准差最小为目标优化干旱期分行业需水,提出了水库旱限水位优化方法。以汾河水库与汾河二库为例进行优化效果分析,验证方法的合理性和可行性,结果表明:以优化后的旱限水位指导水库调度,可降低枯水年内的月缺水率均值及标准差;以50%作为严重缺水率阈值,优化后的旱限水位能够有效降低严重缺水月数;在连枯水年内,优化后旱限水位控制水库调度效果明显优于未优化的旱限水位,优化后旱限水位能够降低严重缺水情况的发生频率,符合枯水年内宽浅式破坏要求;旱限水位的设置保障了枯水年内各行业的用水安全,可减少极端缺水情况的发生,为旱灾防御指挥决策提供依据。     

Socio-Economic Impact of Evaporation Losses from Reservoirs Under Past, Current and Future Water Availability Scenarios in the Semi-Arid Segura Basin

This study assesses evaporation losses from water reservoirs in the semi-arid Segura basin (south-east Spain), one of the most water stressed European catchments. These losses are evaluated from both the hydrologic and economic perspectives under different water availability scenarios that are based on water policy trends and climate change predictions. We take a multidisciplinary approach to the analysis, combining energy balance models to assess the effect of climate change on evaporation from water bodies, Class-A pan data and pan coefficients to determine evaporation loss on a regional scale, and non-linear mathematical programming modelling to simulate the economic impact of water use and allocation in the basin. Our results indicate that water availability could be reduced by up to 40 % in the worst-case scenario, with an economic impact in the 32–36 % range, depending on the indicator in question. The total annual evaporation loss from reservoirs ranges from 6.5 % to 11.7 % of the water resources available for irrigation in the basin, where evaporation from small reservoirs is more than twice that from large dams. The economic impact of such losses increases with water scarcity, ranging from 4.3 % to 12.3 % of the value of agricultural production, 4.0 % to 12.0 % of net margin, 5.8 % to 10.7 % of the irrigated area, and 5.4 % to 13.5 % of agricultural employment. Results illustrate the importance of evaporation losses from reservoirs in this region and the marked upward trend for future scenarios. Besides, they highlight the extent of the impact of climate change on future water resources availability and use in southern Europe.     

Application of Integrated Hydrologic and River Basin Management Modeling for the Optimal Development of a Multi-Purpose Reservoir Project

Multi-purpose reservoir development have been always a big challenge for the management of water resources. This paper describes an integrated approach for investigating catchment hydrology in the development of a hydropower and a canal irrigation system based on model analyses. The investigation aims to adequately determine an optimal domestic and irrigation water resources allocation scheme based on an assessment of the reservoir water balance and capacity for hydropower. The soil and water assessment tool (SWAT) which characterizes basin hydrology and the water management and planning model MODSIM which provides a decision support system for water allocation optimization, were used in this study. The integrated approach was applied to Prek Te River basin in Cambodia. The water demand aspect was examined based on domestic water use, irrigation water, environmental flow, and water losses. An operational rule curve was developed for hydropower operation with respect to a power potential of 13 MW. Hydrologic modeling revealed 90 % dependable water of about 2.7 m³/s during the dry season and 214.3 m³/s during the wet season, indicative of a wet-season dependent reservoir for storage. Results from the 26-years simulation period also showed that diversions for domestic water and irrigation water supply were 92.3 % dependable for a 13 MW capacity hydropower development. The integrated approach was shown to be a valuable decision support tool for water resources management with the determination of an optimum policy for multi-purpose reservoir operation based on available basin water supply.     

基于宏观经济模型和系统动力学的张掖盆地水资源供需研究

针对黑河流域中游张掖盆地水资源供需问题,采用宏观经济模型和系统动力学结合的方法,构建了张掖盆地水资源系统动力学模型,设计5个情景模拟张掖盆地2013-2050年水资源供需平衡状况。结果表明:宏观经济模型与系统动力学的结合能更好地刻画系统行为,准确合理地预测需水量;预测期内张掖盆地需水量逐年增长,年均总需水量为21.87×108~30.14×108m3,缺水年的年均缺水量为4.03×108~7.64×108m3,缺水时间占比为31.6%~92.1%,缺水年平均缺水指数为0.1413~0.2217;综合考虑社会经济发展、城镇化和水资源节约的情景S5是最符合可持续发展内涵和原则的情景;水资源的可持续发展,不仅需要政府的政策引导,更需要公众的参与,只有政府与公众的协调一致,才能保证水资源和社会经济的可持续发展。     

北京市水资源供需二次平衡的系统动力学模拟与研究

针对北京市水资源利用中存在的问题,对该市2012-2030年的水资源供需进行了系统动力学模拟。结果表明:北京市水资源供需矛盾突出,2020年和2030年分别缺水10.95×10~8和8.44×108m~3,缺水率31.33%和20.75%;二次供需平衡情景下该矛盾得到较大改善,2020年和2030年分别富余水2.36×10~8和4.43×108m~3,但这种富余是追求资源、环境保护而忽视经济发展而获得的,对于北京市来说不太能接受;为了维持经济、资源和环境的和谐发展,北京市需要增强人们节约、保护水资源的意识,才能保证水资源供需的长久平衡。     

Multi-Objective Optimization Model for the Allocation of Water Resources in Arid Regions Based on the Maximization of Socioeconomic Efficiency

The escalating world population has led to a drastic increase in water demand in the municipal and drinking water, agriculture and industry sectors. This situation necessitates application of effective measures for the optimal and efficient management of water resources. With this respect, a two-objective socioeconomic model (aimed at job creation) has been presented in this study for the optimum allocation of water resources to industry, agriculture and municipal water sectors. In the agriculture sector, the production function of each product has been determined and then, based on the production functions, areas under cultivation, product yield and the income obtained from each product, the combined objective function has been specified. In the industry sector, since water demand is a function of the amount of produced products, price of supplied water and the price of other supplies, the demand function of this sector was determined regionally. Also, considering the existing necessity in meeting the municipal water requirement, the total amount of water needed by this sector was fully allocated. Then by using two meta-heuristic algorithms, i.e. genetic algorithm (GA) and particle swarm optimization (PSO), the objective functions were maximized and the water resources were optimally allocated between agriculture and industry sectors and the results were compared. Ultimately, comparing the results gained by PSO and GA algorithms, PSO with an economic and profit growth of 54 % and a 13 % rise in employment relative to the base condition, turned out to be more efficient in this application.