Simulation-Optimization Modeling of Conjunctive Use of Surface Water and Groundwater

Water resources management in semiarid regions with low precipitation and high potential of evapotranspiration is a great challenge for managers and decision makers. In those regions, both sources of water should be managed conjunctively so as to minimize shortages of water in dry seasons. In conjunctive use, the difficulty increases as one must represent the response of both systems interactions, and develop management strategies that simultaneously address surface water and aquifer regulation. This paper focuses on the simulation-optimization for conjunctive use of surface water and groundwater on a basin-wide scale, the Najafabad plain in west-central Iran. A trained artificial neural network model is developed as a simulator of surface water and groundwater interaction while a genetic algorithm is developed as the optimization model. The main goal of the simulation-optimization model is to minimize shortages in meeting irrigation demands for three irrigation systems subject to constraints on the control of cumulative drawdown of the underlying water table and maximum capacity of surface irrigation systems. To achieve the main goal, three scenarios are presented. Results of the proposed model demonstrate the importance of the conjunctive use approach for planning the management of water resources in semiarid regions.     

Conjunctive Use of Surface Water and Groundwater: Application of Support Vector Machines (SVMs) and Genetic Algorithms

Combined simulation-optimization models have been widely used to address the management of water resources issues. This paper presents a simulation-optimization model for conjunctive use of surface water and groundwater at a basin-wide scale, the Zayandehrood river basin in west central Iran. In the Zayandehrood basin, in the past 10 years, a historical low rainfall in the head of the basin, combined with growing demand for water, has triggered great changes in water management at basin and irrigation system level. The conjunctive use model that coupled numerical simulation with nonlinear optimization is used to minimize shortages of water in meeting irrigation demands for four irrigation systems. Constraints guarantee the maximum/minimum cumulative groundwater drawdown and maximum capacity of irrigation systems. A support vector machines (SVMs) model is developed as a simulator of surface water and groundwater interaction model while a genetic algorithm (GA) is used as the optimization model. Conjunctive use model runs for three scenarios. Results show that the accuracy of SVMs as a simulator for surface water and groundwater interaction model is good and that it is possible to decrease the water shortage for irrigation systems with application of proposed SVMs-GA model.     

Mitigating Socio-Economic-Environmental Impacts During Drought Periods by Optimizing the Conjunctive Management of Water Resources

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.     

玛纳斯河灌区地表水与地下水联合调度模型

通过分析新疆农八师玛纳斯河灌区水资源供需状况,结合灌区的灌溉系统、农作物种类及灌溉制度,建立了以灌区地下水抽水总量最小为主要目标,以灌区农业经济总效益最大为次要目标的地表水与地下水联合调度模型,并采用目标规划法对模型进行了求解,得到了在不同保证率下灌区地表水和地下水联合调度方案及农作物种植面积。结果表明:灌区供需水高峰期不一致和灌溉系统的蓄水、输配水能力不足是产生灌区水资源供需矛盾的主要原因,应适当调整灌区农业种植结构,改造灌区水利工程。     

A water balance modelling approach to optimising the use of water resources in ephemeral sand rivers

Alluvial aquifers present a possibility for conjunctive use with surface reservoirs for the storage of water in ephemeral sand rivers such as the Mzingwane River in the Limpopo Basin, Zimbabwe. The Lower Mzingwane valley is a semi‐arid region with high water stress, where livelihoods have revolved around the large rivers for thousands of years. However, current water allocation favours the commercial user: of the 2600 ha irrigated in the 5960 km² (596 000 ha) region, only 410 ha are for smallholder farmers. A water balance approach was used to model the surface water resources and groundwater resources to determine the potential for expanding irrigation and to explore water allocation options. Using a combination of field and laboratory investigations, remote sensing and existing data, the Lower Mzingwane valley was modelled successfully using the spreadsheet‐based model WAFLEX, with a new module incorporated to compute the water balance of alluvial aquifer blocks. Results showed that the Lower Mzingwane alluvial aquifers can store 38 × 10⁶ m³ of water, most of that storage being beyond the reach of evaporation. Current water usage can be more than tripled: the catchment could supply water for currently‐planned irrigation schemes (an additional 1250 ha), and the further irrigation of two strips of land along each bank of the Mzingwane River (an extra 3630 ha)—without construction of any new reservoirs. The system of irrigating strips of land along each bank of the Mzingwane River would be decentralized, farmer or family owned and operated and the benefits would have the potential to reach a much larger proportion of the population than is currently served. However, there could be substantial downstream impact, with around nearly one‐third of inflows not being released to the Limpopo River. The approach developed in this paper can be applied to evaluate the potential of alluvial aquifers, which are widespread in many parts of semi‐arid Africa, for providing distributed access to shallow groundwater in an efficient way. This can enhance local livelihoods and regional food security. Copyright © 2010 John Wiley & Sons, Ltd.     

Optimizing Water Management for Irrigation Under Climate Uncertainty: Evaluating Operational and Structural Alternatives in the Lower Republican River Basin,Kansas, USA

Structural and operational management methods are used to meet water demands in watersheds around the world. Most river systems are affected by reservoirs, dams, or other engineering structures, and decisions regarding their construction and operation are made in advance of knowing what water demands will be. Numerical models are used to predict future water needs and evaluate the effectiveness of water management strategies. It is important to consider a variety of management methods and future environmental conditions to ensure future demands can be met. In this work, a coupled surface water operations and hydrologic model of the Lower Republican River Basin in portions of Nebraska and Kansas, USA is used to evaluate the ability of several water management strategies, including structural and operational, to meet future demands of a water-stressed agricultural basin under a variety of future climate scenarios. Simulations indicate recent administrative and operational changes to the distribution of water between Nebraska and Kansas have significantly decreased water shortages for irrigation districts in Kansas and will continue to do so. Simulations also indicate that structural alternative of reservoir expansion is most effective at minimizing shortages to demands under a repeat of historical climate conditions. However, an operational alternative of increasing water supplies for Kansas' exclusive use, such as those historically purchased under the Warren Act (US Code 43 Section 523–524), is most effective at minimizing shortages to demands under a hotter and drier climate, demonstrating how optimal water management strategies can vary significantly depending upon climate scenario.     

面向发电、供水、生态要求的赣江流域水库群优化调度研究

以赣江流域内已建成的大型控制性水库为研究对象,将赣江流域上游至下游用水区概化成7个主要用水区域,综合考虑各水库的运用目标、流域主要用水区域水量需求以及河道内生态流量的要求,以水库群总发电量最大、用水区域总缺水量最小和外洲控制站调度后流量与天然流量偏差最小为目标,建立面向发电、供水、生态要求的赣江流域水库群优化调度模型,采用多目标粒子群算法进行求解,得到不同来水频率下发电、供水和生态3个目标的非劣解集,并对3个目标之间的竞争关系进行了剖析。最后分析了各典型方案相应的水库水位过程和区域缺水情况。结果表明:各来水频率下,发电、供水、生态3个目标之间竞争程度有强有弱,其中发电目标与生态目标之间、供水目标与生态目标之间存在较强的竞争性,发电目标与供水目标之间则相对较弱。     

乌江流域水电站群优化调控关键技术应用研究

根据乌江流域总体规划、长江三峡以上防洪要求、南方电网运行特点及乌江流域水文特性等．开展了乌江梯级水库优化调度和发电优化控制的基本理论研究，建立了乌江流域水电站群联合优化调控系统，其在系统中应用，实现了节水增发电的目的，取得了良好的社会经济效益。     

Applicability of Adapted Reservoir Operation for Water Stress Mitigation Under Dry Year Conditions

This paper introduces the conjunctive use of a deterministic water quality model and water balance criteria for supporting the assessment of simulation and to evaluate the effectiveness of proposed operation strategies. By this, the applicability of enhanced reservoir operation strategies addressing both water quality as well as water quantity aspects under water deficit conditions in dry years can be shown. Arguments will be developed to address stakeholders and decision makers in the context of a more conservative past operation regime. Results are presented for the Kaparas reservoir, which is located in the lower Amu Darya River, on the border of Turkmenistan and Uzbekistan. As being one out of four large reservoirs of the Tuyamuyun Hydro Complex (THC), the Kaparas reservoir could be increasingly used for drinking water supply for the lower Amu Darya region. The results for the dry year 2001 indicates that the combination of simulation together with practical assessment criteria confirm the applicability of adapted operation rules for THC reservoirs and ways can be found to supply the local population (of the lower Amu Darya region) with more potable water of higher quality even subject to a parallel reduction of water deficits. Future aggravation of water stress due to increasing population growth and water quality deterioration will require a more comprehensive consideration of water quality aspects in many arid and semi arid regions. The experience gained during this study emphasizes the fact that classical deterministic water quality models provide effective tools to address even more complex water quality problems under water stressed conditions, provided processing of results is performed, to support the decision making process.     

Reuse of oil and gas produced water in south-eastern New Mexico: resource assessment,treatment processes,and policy

The Permian Basin of south-eastern New Mexico in the United States exemplifies the combination of rapidly expanding oil and gas production with freshwater shortages and aquifer stress. Reuse of saline produced water can provide a stable supply of water for drilling, fracturing and completion and minimize consumptive use of freshwater. We discuss water withdrawals and use by the oil and gas industry in this region, processes for reuse and recycling of produced water in place of freshwater, and operational and policy changes to help improve maximal use of all available water resources in this arid region.     

Sustaining Urban Water Supplies in India: Increasing Role of Large Reservoirs

Urban water demand is rapidly growing in India due to high growth in urban population and rapid industrialization. Meeting this demand is a big challenge for the urban planners in India. Incidentally, the large urban areas are experiencing faster growth in population, and most of them are in arid and semi arid regions, which are naturally water-scarce. As a result, water supplies from local water resources including aquifers are falling far short of the high and concentrated demands in most urban areas. Under such situations, these large cities have to rely on distant large reservoirs. The analysis of 302 urban centers shows that cities with larger population size have much higher level of dependence on surface water sources. Also, greater the share of surface water in the city water supplies, higher was the level of per capita water supply. Multiple regression models are estimated for Class I cities and Class II towns in India. The results show that Population Elasticity of Water Supply (PEWS) change with time and space—for Class I cities it was 1.127 in 1988, whereas that with respect to 1999 population is 1.289. It also shows that Class I cities have better water supply (PEWS is 1.127 in 1988 and 1.289 in 1999) than Class II towns (PEWS is 0.396 in 1988 and 0.675 in 1999). Given the structure and pattern of urban population growth, economic conditions and water demands, large reservoirs will have a much bigger role in meeting urban water supply needs.     

Simulation-Optimization Modeling of Conjunctive Operation of Reservoirs and Ponds for Irrigation of Multiple Crops Using an Improved Artificial Bee Colony Algorithm

Seasonal drought has become an important factor in agricultural production in humid and semi-humid areas. In this study, to mitigate the impact of seasonal drought, a new integrated mathematical model is proposed for optimal multi-crop irrigation scheduling, which is associated with conjunctive operation of reservoirs and ponds to maximize the annual returns for a reservoir-pond irrigation system. This objective is achieved via the use of two models: an operating policy model, which considers the regulatory role of ponds and optimizes reservoirs and ponds releases in one third of a month, and an allocation model, which optimizes irrigation allocations across crops by addressing water production function. The uneven distribution of ponds is also considered by dividing the irrigation district into many sub-districts. Artificial bee colony algorithm is innovatively improved by incorporating differential evolution algorithm and particle swarm optimization algorithm to solve this nonlinear, high-dimensional and complex optimization problem. The methodology is applied to the Zhanghe Irrigation Distict, which is located in Hubei Province of China, to demonstrate its applicability, and three additional models are simulated to demonstrate the validity of the integrated model. The results indicate that the integrated model can alleviate the impact of the seasonal drought and has remarkable optimization effect, especially for drought years. The average annual return calculated by the integrated model is 7.9, 7.0 and 3.1 % higher than that of the remaining three models, respectively. And in the special dry year, in which the frequency of rainfall is 95 %, the annual return calculated by the integrated model is 24.5, 21.8 and 10.1 % higher than that of the remaining three models, respectively.     

NeStRes – Model for Operation of Non-Strategic Reservoirs for Irrigation in Drylands: Model Description and Application to a Semiarid Basin

Water availability in dry inhabited environments has usually been promoted by large strategic reservoirs, but small non-strategic ones, built by farmers and communities, are unable to cope with long term droughts and inappropriate for human supply. Nevertheless, small reservoirs promote water spatial distribution and play a major role for livelihood in rural areas. To fill the gap of operation methods for non-strategic reservoirs used for irrigation where water is a limiting factor, the NeStRes model was developed. The model is composed of three modules: i) hydrological: to define the reliability of water withdrawals from the reservoir; ii) agricultural: to simulate crop production based on water availability; iii) economic: to compute the possible income from irrigated agricultural crops. NeStRes was applied to 91 reservoirs of the semiarid Banabuiú River Basin – BRB, Brazil. The simulations indicated that the maximum income from the cultivation of maize is obtained when the reservoirs are intensely used, drying completely in one to two thirds of the time. Adoption of a fixed reliability level of daily water supply (54%, in the BRB) generates at least 85% of the maximum possible income for all simulated reservoirs. This model application suggests a paradigm change in the operation of small non-strategic reservoirs in drylands: to use water for crop production and save the revenue, instead of saving water, which is susceptible to evaporation. Although high reliability level is desired for human supply by strategic reservoirs, non-strategic ones can be more intensely explored to generate income from irrigated agriculture in drylands.

     

基于生态水文阈值调控的内陆干旱区水资源多维均衡配置研究

针对内陆干旱区城市发展和生态环境保护的强烈互斥性,在整体识别内陆干旱区水循环与生态演变耦合作用机理上,构建基于生态水文阈值调控的水资源多维均衡配置模型。模型分3个层次:以流域为单元的水资源系统耗水总量和地下水采补平衡;以行政分区为单元的经济社会系统水量平衡和水土平衡;以河道关键控制断面和灌区为单元的生态环境系统水生态平衡和水盐平衡,并给出相应的多重循环迭代算法。将该模型方法应用于我国内陆干旱区——塔里木河流域,结果显示:在平枯水平年通过累计新增节水灌溉面积85.1万hm~2,累计退减基本农田外灌溉面积41.5万hm~2,累计退减国民经济用水量为75亿m~3,可实现该地区水资源-经济社会-生态环境复合系统的有序良性演化和高效均衡发展,验证了该方法的可行性。     

Water Balance within Intensively Cultivated Alluvial Plain in an Arid Environment

The Tuoshigan–Kumalake River alluvial plain is an oasis located in the Tarim River Basin of Xinjiang, China. Large water consumption reduces the discharge and jeopardizes the ecosystem of the lower reaches of the Tarim River. Therefore a recent regulation is enacted to limit water use in the plain. The objective of this paper is to investigate the hydrological cycle inside an intensively cultivated plain at upstream Tarim River. A conceptual water balance methodology was used for evaluating groundwater movement among riverway, irrigation ditches, irrigation area and non-irrigation area, based on the recorded water diversion. Results show that both irrigation area and non-irrigation area are supported by the water from river way in hyper-arid environment. Irrigation area is supported by surface water through canal system and non-irrigation area is supported by groundwater from canal loss and irrigation area. Nearly half of the water in the non-irrigation area comes from the irrigation area in the form of groundwater. This indicates that water supply of natural plants relies on the water from agricultural ecosystem. Tight water connection between irrigation area and non-irrigation area suggests that natural ecosystem needs to be considered in agricultural management in arid environment.     

面向多区域防洪的长江上游水库群协同调度模型

长江上游水库群是长江流域防洪工程体系的重要组成部分,承担着水库所在河流、川渝河段以及长江中下游的防洪任务。长江流域面积广大,水系众多,洪水地区组成与遭遇十分复杂,防洪需求众多,防洪对象分散,且要兼顾发电、航运、供水、生态、库区安全等多种因素,水库群防洪调度面临大规模、多区域、多层次等协同调度技术难题。以长江上游25座控制性水库为研究对象,基于防洪格局和防洪任务将水库群防洪调度划分为核心、骨干和群组水库,阐明了水库群多区域协调防洪的调度节点和角色定位,提出了兼顾"时-空-量-序-效"多维属性的模型功能结构,构建了长江上游水库群多区域协同防洪调度模型,并在长江流域防洪调度形成示范应用,以挖掘长江上游水库群防洪调度潜力,进而提升长江流域防洪调度管理水平。     

花都北部山区水库群可利用水量分析研究

针对花都北部山区水库群的特点,在满足水库群自身的防洪、供水、灌溉等任务的前提下,充分利用水库群的兴利库容,采用长系列径流调节计算方法,通过列表试算求解得设计保证率下水库群的可利用水量.与传统的典型年计算方法相比,长系列径流调节计算方法理论合理,操作性强,成果更为可靠.     

Simulating system‐wide effects of reducing irrigation withdrawals in a disputed river basin

Stakeholders in river systems often target larger upstream water consumers as an intuitive solution for increasing flows for downstream ecological needs. Within regulated river systems, simplistic panaceas may have unexpected and unintended results at a watershed level. The Apalachicola–Chattahoochee–Flint River Basin is a large watershed in the south‐eastern United States whose management has been the source of conflict for several decades. This paper tests the hypothesis of whether a reduction in consumptive losses to Flint River flows through the large‐scale implementation of water‐saving agricultural irrigation technologies and practices will have a positive effect on downstream ecosystem water requirements in the Apalachicola River. An existing integrated reservoir/reach model was used to explore multiple irrigation water use scenarios. Because of current federal reservoir operating rules in the Chattahoochee River, irrigation decreases in the Flint River do not always directly translate to elevated flows downstream in the Apalachicola River. In drought years, a large percentage of the Flint River water savings is captured as greater storage volume at upstream Chattahoochee reservoirs because of a requirement to supplement downstream flows to a prescribed minimum level. In nondrought years, the majority of irrigation decreases translate to increased flow in the Apalachicola River. Given these simulation results, public policy decisions need to be formulated with regard to what portion of the Flint River water savings from changing irrigation practices in drought years should be allocated to the upstream Chattahoochee storage reservoirs and what portion to supporting downstream environmental and social needs in the Apalachicola watershed.     

Multiobjective water resources systems analysis using genetic algorithms--application to Chou-Shui River Basin, Taiwan.

Multipurpose operation is adopted by most reservoirs in Taiwan in order to maximize the benefits of power generation, water supply, irrigation and recreational purposes. A multiobjective approach can be used to obtain trade-off curves among these multipurpose targets. The weighting method, in which different weighting factors are used for different purposes, was used in this research work. In Taiwan, most major reservoirs are operated by rule curves. Genetic algorithms with characteristics of artificial intelligence were applied to obtain the optimal rule curves of the multireservoir system under multipurpose operation in Chou-Shui River Basin in central Taiwan. The model results reveal that different shapes of rule curves under different weighting factors on targets can be efficiently obtained by genetic algorithms. Pareto optimal solutions for a trade-off between water supply and hydropower were obtained and analyzed.