An integrated hydro-economic modelling framework to evaluate water allocation strategies II: Scenario assessment

In this paper the results of an assessment of the hydrological and economic implications of reallocating water in the Musi sub-basin, a catchment within the Krishna Basin in India, are reported. Policy makers identified a number of different but plausible scenarios that could apply in the sub-basin, involving; supplying additional urban demand from agricultural allocations of water, implementing a number of demand management strategies, changing the timing of releases for hydropower generation, changing the crops grown under irrigation, reducing existing stream flows and allowing for more environmental flows. The framework chosen to undertake this assessment was a simulation model that measures and compares the economic values of water allocation scenarios determined from a water allocation model that accounts for supplies of groundwater and surface water across a number of regions and over a variety of uses. Policy makers are provided with the range of measures on the security of the supply of water and the social costs and benefits of reallocating water between sectors and across regions within the sub-basin. Taking water from agriculture to supply urban users has a greater impact on irrigation supplies during dry years. It was also found that changing the allocation of water between sectors, by taking it away from agriculture had a large positive economic impact on the urban sector. Yet the costs involved in undertaking such a strategy results in a significant loss in the net present value of the scheme. Stream flow reductions, if significantly large (at around 20%), were found to have a large physical and economic impact on the agricultural sector. Implementing water saving strategies in Hyderabad was found to be more cost effective than taking water from agriculture, if rainwater tanks are used to achieve this. Changing the timing of hydropower flows resulted in best meeting of irrigation demand in NSLC and NSRC. Under this scenario, the crops grown under irrigation were found to have a significant economic impact on the sub-basin, but not as large as farmers undertaking crop diversification strategies, ones which result in farmers growing less rice. The security of supplying water to different agricultural zones has significantly improved under this scenario. Finally, releasing water for environmental purposes was found to have only a minor impact on the agricultural sector.     

井渠结合灌区水资源多目标优化配置模型与应用

将灌区的经济效益和生态环境效益结合在一起综合考虑,在灌区水资源配置时不仅只追求获得最大经济效益,同时尽量将地下水位控制在适宜范围内,以维持地下水资源的采补平衡,实现水资源的可持续利用。按此原则,建立了井渠结合灌区水资源多目标优化配置模型。实例计算表明：应用此模型指导井渠结合灌区的水资源配置可实现真正意义上的地表水和地下水联合运用,提高水资源利用效率。     

An integrated water trading-allocation model, applied to a water market in Australia

Temporary water trading is an established and growing phenomenon in the Australian irrigation sector. However, decision support and planning tools that incorporate economic and biophysical factors associated with temporary water trading are lacking. In this paper the integration of an economic trading model with a hydrologic water allocation model is discussed. The integrated model is used to estimate the impacts of temporary water trading and physical water transfers. The model can incorporate economic and biophysical drivers of water trading. The economic model incorporates the key trade drivers of commodity prices, seasonal water allocations and irrigation deliveries. The hydrologic model is based on the Resource Allocation Model (REALM) framework, which facilitates hydrologic network simulation modelling. It incorporates water delivery system properties and operating rules for the main irrigation and urban centres in a study area.The proposed integration method has been applied to a case study area in northern Victoria, Australia. Simulations were conducted for wet and dry spells, a range of commodity prices and different irrigation distribution system configurations. Some example analyses of scenarios incorporating water trading were undertaken. From these analyses potential bottlenecks to trade that constrain the economic benefits from temporary water trading were identified. Furthermore, it was found that in certain areas of the system, trading can make impacts of long drought spells worse for water users, e.g. irrigators. Thus, the integrated model can be used to quantify short-term and long-term third party impacts arising from temporary water trading. These findings also highlight the need to link “paper trades” (estimated by economic models) to physical water transfers (estimated by biophysical models).     

Integrated hydrologic-economic modelling for analyzing water acquisition strategies in the Murray River Basin

We describe a coupled hydrologic-economic spreadsheet model for the Murray-Darling Basin that allows analyses of water allocation and use by different sectors including agriculture and environment under alternative policy scenarios. The model is a simple, lumped optimisation model which includes partitioning of rainfall into runoff and evapotranspiration, a reach by reach water balance of the river system, irrigation demand and revenue generation. Groundwater is not considered because groundwater use is a small part of the overall water use. The model is used to optimize profit, diversions and flows subject to hydrological and economic constraints determined by the policy scenario.We use the model to examine approaches of acquiring water for reallocation to the environment, and their impacts on irrigation water use and regional income from agriculture. We show that the optimal approach for acquisition depends on: economic factors, including the cost of water and the profits generated by its use; institutional factors, such as restrictions to trade between regions; and, hydrological factors, particularly the connectivity of and losses within the river network.The volume of water to be acquired does not, in general, equal the volume to be allocated. For a downstream site, water must be acquired from upstream, and more water must be acquired than is to be allocated: the volume acquired is that to be allocated plus transmission losses between the locations of acquisition and allocation. For upstream sites, it is optimal to acquire some water from downstream, and less water must be acquired than is to be allocated: the volume acquired is that to be allocated, less the transmission losses no longer incurred between the locations of acquisition and allocation.The volumes of water that must be acquired to satisfy an allocation target and maintain flows in the river system are affected by restrictions on trade between sub-catchments.     

Pricing of irrigation water under alternative charging methods: Possible shortcomings of a volumetric approach

The European water framework directive aims to protect the environmental quality of water and encourage its efficient use. EU member states are required to implement efficient water management systems and appropriate water-pricing methods. This paper examines the economic effects that may arise given the introduction of two different methods for pricing irrigation in the Mediterranean area. The considered pricing methods charge farmers for the costs incurred by water user associations (WUAs) in managing water distribution networks. The first method, based on the metered use of water by farms, is known as the volumetric pricing method. The second is an area-based pricing method, whereby fees are charged per hectare according to the estimated average water use for each crop. The economic effects and the impacts on the water usage of these two schemes are analyzed using a mathematical model that represents the farm sector in a Mediterranean area that relies on a dam for irrigation. The possible effects are analyzed under two scenarios: first, the methods are applied to the observed water-pricing conditions, second, an additional charge is introduced to recover unaccounted costs of the water supply system (e.g., long-term costs related to infrastructure, and the operational and maintenance costs of dams) in line with the water framework directive principle of cost recovery. The results show that the introduction of an additional charge via the volumetric pricing method could stimulate the substitution of water provided via collective networks with groundwater. This could adversely affect the financial situation of the WUA and have negative environmental consequences. This negative outcome does not arise in the case that an additional charge is applied via the area-based pricing method.     

Designing contracts for irrigation water under asymmetric information: Are simple pricing mechanisms enough?

A fertile discussion is developing in the EU regarding the application of the Water Framework Directive (60/2000) (WFD), the legislative act that provides the framework for water regulation in Europe and emphasises the role of economic instruments in water policy. The objective of this paper is to provide an evaluation of different instruments designed to deal with the management of water for agriculture, in the perspective of WFD implementation and agricultural price scenarios. The paper focuses on the regulation of mixed source unmetered water and carries out a comparison of flat rate versus differentiated contracts as the policy instrument. The analysis is based on a combination of linear programming and a Principal-Agent model. The empirical model is applied in an agricultural area of Northern Italy. The results show the feasibility of incentive-oriented policy instruments, even in the less sophisticated form of flat rate area payments. They also show the relevance of agricultural market scenarios and policy scenarios in the design of the optimal policy instruments. The adoption of such instruments, however, could require a revision of the role of different institutions involved in water management.     

基于2型模糊集的多目标农业-生态水土资源优化配置

针对西北干旱区灌区生态环境脆弱、水资源短缺、复杂不确定性等问题,以石羊河流域红崖山灌区为例,耦合2型模糊集、模糊可信度约束规划和多目标规划等理论方法,构建了基于2型模糊集的多目标农业-生态水土资源优化配置模型。模型以灌溉水损失最小、生态植被灌溉水满意度最大、生态植被灌溉水费用最小和主要粮食作物经济效益最大为目标,对红崖山灌区10个决策单元的地表水、地下水和粮食作物种植面积进行优化配置。求解模型得到不同可信度水平和不确定性程度下的水土资源优化配置方案。结果表明：耦合2型模糊集的模型能够提供丰富的配置方案,水量对可信度水平的敏感性高于不确定性程度,作物种植结构对可信度水平不敏感。以不确定性程度参数为0.5、可信度水平为0.7时为例,生态植被均通过地表水灌溉,作物通过地表水、地下水联合灌溉,玉米的产量和经济效益均大于小麦。相比前人研究,本研究考虑生态植被灌溉需求,优化结果更加真实合理。本研究可为决策者提供较为符合灌区实际的配置方案,为西北干旱区灌区现代化建设提供科学指导。     

Estimating potential costs and gains from an aquifer storage and recovery program in Australia

Artificial recharge of aquifer storage can provide water during drought periods, reverse falling groundwater levels and reduce water losses associated with leakage and evaporation, as compared with surface water storage. We examine the technical and economic potential of artificial storage and recovery for drought mitigation in the Murrumbidgee Region of New South Wales, Australia. Potential locations for infiltration basins and injection/recovery wells are identified according to criteria such as water availability, aquifer suitability, recharge potential, and potential to provide a usable resource. The estimated annual artificial recharge potential is 180,000 ML through a combination of injection wells and infiltration basins. The cost estimates for artificial recharge vary from AU$ 62 ML⁻¹ to AU$ 174 ML⁻¹ depending on the choice of recharge method. Underground storage capacity can be developed at less than half the cost of surface storage facilities without undesirable environmental consequences or evaporation losses. The estimated benefits of artificial storage and recovery through infiltration basins are three to seven times the costs, during low allocation years.     

河套灌区井渠结合地下水数值模拟及均衡分析

建立了河套灌区三维地下水数值模型,用2006-2013年灌区实测地下水埋深资料对模型进行率定和验证,并在规划的井渠结合区内,设置3种不同井灌区灌溉定额和3种秋浇频率,组合共9种井渠结合节水情景,分别分析了9种节水情景下的地下水动态变化.结果表明:井渠结合后全灌区地下水埋深范围为1.863~2.029 m,较现状条件增加0.084~0.250 m;不同灌域结合区井渠结合后地下水埋深差别很大,解放闸结合区地下水埋深最大,为2.308~2.803 m,永济结合区地下水埋深最小,为2.079~2.455 m;井渠结合后,入渗补给量减少2.01×10⁸ ~3.63×10⁸ m³/a,潜水蒸发量减少1.69×10⁸ ~3.03×10⁸ m³/a.     

Policy incentives for reducing nitrate leaching from intensive agriculture in desert oases of Alxa, Inner Mongolia, China

Excessive irrigation and nitrogen applications result in substantial nitrate leaching into groundwater in intensively cropped oases in desert areas of Alxa, Inner Mongolia. An integrated modelling approach was developed and applied to compare policy incentives to reduce nitrate leaching. The integrated model consists of a process-based biophysical model, a meta-model, a farm economic model and an assessment of policy incentives. The modelling results show that there are “win-win” opportunities for improving farm profitability and reducing nitrate leaching. We found that 4471 Yuan ha⁻¹ of farm gross margin could be obtained with a reduction in nitrate leaching of 373 kg ha⁻¹. Farmers’ lack of knowledge about water and nitrogen in soil, and on crop requirements for water and nitrogen could explain the differences, so that agricultural extension is an appropriate policy incentive for this area. When the economic optimum is obtained reductions in nitrate leaching are not achievable without profit penalties and there is a “trade-off” relationship between farm profitability and groundwater quality protection. The combination of low elasticity of nitrate leaching and large elasticity of farm gross margin against water price increases results in very high costs for reducing nitrate leaching (105.6 Yuan kg⁻¹). It is suggested that if the water price increases were coupled with subsidies for adopting nitrate leaching mitigation practices, environmental gains could come at a lower cost.     

Determining the disaggregated economic value of irrigation water in the Musi sub-basin in India

In this paper the residual method is used to determine the disaggregated economic value of irrigation water used in agriculture across crops, zones and seasons. This method relies on the belief that the value of a good (its price by its quantity) is equal to the summation of the quantity of each input multiplied by its average value. By applying this method to the Musi sub-basin; a subdivision of the Krishna basin in India, it was found that the value of irrigation water use is not equated across the crops, zones and seasons. The reasons why there is no sinlge value of irrigation water use are suggested. As farmers do not have perfect knowledge, do not all possess the same resource base, plant different crops for a variety of reasons (some for a financial return on land instead of water and others for sustenance), possess different crop rotation practices and are possibly riks adverse, they all value water differently. However, the results need to be interpreted with care as the crop with the lowest return to water is probably not the one to be sacrificed if water is restricted, since farmers plant crops for a variety of reasons (and sometimes not for the highest return to water that they can achieve).     

基于两阶段优化配置模型的济南泉域补给区灌溉水源置换研究

目前全球地下水能保持持续平衡的地区日趋减少,不合理农业灌溉成为很多地区地下水系统恶化的主要因素之一。济南市历城区地下水用于农业灌溉是当地地下水位下降的重要因素,对于济南泉域、白泉泉域喷涌有直接影响。针对研究区农业用水特点和水生态文明建设水源置换的要求,建立两阶段优化配置模型,将灌溉用水配置分为2个阶段,阶段一,以生态、节水和经济效益为目标,引入单位脉冲响应系数约束地下水利用量,实现区域地下水与地表水的合理配置;阶段二,以作物最大产量为目标,进行作物生育阶段水量配置和种植结构调整。结果表明,采取两阶段优化算法与用水结构调整后,可以有效减少地下水利用量,2011—2014年平均地表水与地下水用水结构由原来的3∶7调整为5.2∶4.8,较好地实现地下水源置换目标,同时地下水位计算值较实际年分别增加0.31、1.12、1.55和3.38 m,对保证泉域持续喷涌具有重要作用。     

Integration of economic and hydrologic models: Exploring conjunctive irrigation water use strategies in the Volta Basin

We describe the development, calibration and preliminary application of a dynamically coupled economic–hydrologic simulation–optimization model ensemble for evaluating the conjunctive use of surface and groundwater in small reservoir-based irrigation systems characteristic of the Volta Basin, Africa. We focus on a representative small reservoir-irrigation system located in the Antakwidi catchment in Ghana. The model ensemble consists of the physical hydrology model WaSiM-ETH and an economic optimization model written in GAMS. Results include optimal water storage and allocation regimes for irrigated production, given conjunctive surface water and groundwater systems. The goal of our research, conducted within the GLOWA Volta project, is to develop a decision support system for improving the management of land and water resources in the face of potential environmental change in the Volta Basin.     

基于WEAP模型的龙口市水资源优化配置研究

以龙口市为例,利用WEAP(Water Evaluation And Planning,水资源评估和规划系统)软件建立了水资源优化配置模型.该模型把满意度函数作为水资源优化配置模型的目标函数,满意度函数包括3个子函数,即:社会效益、经济效益和环境效益.在不同的节水和经济发展速度下的5个方案进行了模拟计算,求得社会效益,...     

基于水权理论的新疆玛纳斯河水资

新疆玛纳斯流域是新疆最大的绿洲农耕区,该流域自然环境特点和社会经济发展在新疆均具有典型的代表性。玛纳斯河水权分配是玛纳斯河水资源管理改革的重要部分。首先探讨了水权的基本理论和使用权的分配原则,并依据这些原则,构建了水权分配的指标体系。为解决这一多地区多目标的决策问题,本文建立了多层系统半结构性多目标模糊优选的水权分配模型。采用该方法对玛纳斯河水权进行了分配,获得了较为合理的结果。     

An integrated modelling toolbox for water resources assessment and management in highland catchments: Model description

Water and land resource competition and environmental degradation pose difficult questions for resource managers. In particular, the ensuing trade-offs between economic, environmental, and social factors and their spatiotemporal variability must be considered when implementing management policies. This paper describes an integrated modelling toolbox that has been developed for highland catchments – specifically the Mae Chaem catchment in Northern Thailand. This toolbox contains models of crop growth, erosion and rainfall-runoff, as well as household decision and socioeconomic impact models. The approach described advances and complements previous approaches by: considering more complex interactions between land-use decisions and the hydrological cycle; modelling household decisions based on uncertain expectations; and assessing impacts of changes not only on flows and household income, but also on subsistence production and erosion. An example of the types of trade-offs and scenarios that can be assessed using the integrated modelling toolbox is also presented. This demonstrates that for the scenarios presented, the magnitude and direction of impacts simulated by the model is not dependent on climate. Further testing of the model is demonstrated in a companion paper. Overall, the plausibility of the model is shown.     

Optimal decision schemes for agricultural water quality management planning with imprecise objective

Agricultural activities are the main sources of water pollution to surface water and groundwater in rural areas. Extensive soil disturbance and application of fertilizer and manure in agriculture cause nonpoint source losses of soil and nutrients such as nitrogen and phosphorus. How to generate preferred decision schemes for agricultural activities that cause such nonpoint source water pollution is a critical issue for the decision makers. In this study, an inexact agricultural water quality management (IAWQM) model is developed and applied to a case study to generate optimal decision schemes for integrated water quality management within an agricultural system. The model is based on a hybrid fuzzy possibilistic robust programming approach, which improves upon the existing fuzzy possibilistic programming and fuzzy robust programming methods by allowing fuzzy information in the model's objective and constraints to be directly communicated into the optimization processes and resulting solutions. Optimal decision schemes for agricultural activities can be generated, including cropping area, manure/fertilizer applied, and livestock husbandry size, where implications of water quality/quantity restrictions for achieving regional economic development objectives are studied. The results of the case study indicate that useful information can be obtained through the proposed IAWQM model for providing feasible decision schemes, which reflect tradeoffs between economic and environmental considerations. The decision variables are useful for the decision makers to justify and/or adjust the decision schemes for agricultural activities through incorporation of their implicit knowledge on water quality management.     

A water balance model to estimate groundwater recharge in Rechna doab,Pakistan

The main objective of this study was to develop a procedure to evaluate various recharge components of a groundwater reservoir to estimate the long term average seasonal groundwater recharge in Rechna doab in the Punjab province of Pakistan. A regional lumped water balance model for the Rechna doab was developed and applied to estimate the long term a seasonal recharge to groundwater reservoir. For comparison, recharge was also estimated by a specific yield method from observed groundwater levels. A water balance study was conducted on seasonal basis (6 months) for a period of 31 years (1960–1990). Recharge estimated by the two methods was found to be in good agreement. The average value of net groundwater recharge during Kharif (April–September) season was found to be some 60 mm. No recharge occurred during Rabi (October–March), rather there was a depletion of the groundwater reservoir during the winter months. Long term average annual depletion of a groundwater reservoir was found to be greater than corresponding value of annual recharge. It was concluded that on a regional basis the groundwater reservoir was being depleted resulting in an average groundwater table of Rechna doab about 2.3 m fall over the 1960–1990 period.     

Assessment of alternative water management options for irrigated agriculture

A simulation study on alternative water management strategies was carried out for Sirsa Irrigation Circle in Haryana, covering an area of about 4800 km². Results showed that crop evapotranspiration and soil salinity development under reduction in canal water supply and increase in groundwater use, are largely influenced by the amount and distribution of rainfall. Reduction in canal water supply by 25% during the rainy season is unlikely to have any adverse effect on the salinity development in the study area. Reduction in crop evapotranspiration due to decreased canal water supply can partly be compensated by the increase in groundwater use. Leaching of salts due to monsoon rains in the study area shows that groundwater of even relatively poor quality can be used for irrigation without excessive long-term build up of soil salinity under deep groundwater depth conditions. However, increased groundwater extraction without associated actions will not be very effective to solve the problem of rising groundwater levels.     

松花江佳木斯以下干流段地表水与地下水相互转化关系研究

松花江下游干流段地区内地表水与地下水转化频繁,关系复杂。因此开展松花江下游干流段地表水与地下水转化关系的研究对于建立松花江下游干流段内的水循环模式和指导区内水资源的可持续开发利用有重要的实际价值。利用地表水水量平衡法和地下水水量均衡法,在充分分析松花江下游干流段地区的地质、水文地质条件的基础上,通过对地表水的蒸发量、开采量、补给量和排泄量以及地下水的补给量和排泄量的计算,研究了地表水与地下水的转化关系。