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.     

关于灌区末级渠系工程改造的思考

末级渠系（包括斗、农渠系）改造是灌区建设的重要组成部分,群管渠系体系的管理水平直接关系着灌区工程效益的正常发挥。文中对灌区末级渠系工程的建设和管理现状进行探讨,结合末级渠系改造试点地区效益分析,提出了灌区末级渠系建设组织形式、工程规划、设计以及工程造价控制等方面的若干建议。     

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.     

GIS-Integrated Rice Irrigation Management Information System for a River-Fed Scheme

The Tanjung Karang Irrigation Scheme is one of the large rice granaries in Malaysia. Irrigation management for rice irrigation is difficult because of different planting schedules, variability in soil and crop conditions and unreliable intake of water in the main canal due to the absence of storage reservoir and their uneven distribution to tertiary canals. In view of this concern, the scheme needs the daily estimation of the available water for irrigation and its equitable allocation among tertiary canals to cater trade-offs in water use for the scheme. Easy access of these spatially and temporally distributed data helps to make management system simpler. A GIS-integrated tool known as RIMIS was developed for equitable irrigation supply to tertiary canals and the characterization of their irrigation delivery performance as the season advances. RIMIS dynamically links a field irrigation demand prediction model for the area irrigated by a canal network in GIS. The system can correctly simulate and evaluate recommended irrigation supplies among tertiary canals that match the available discharge at the system head with the crop water demand for the actual field conditions. The user-interface was developed using ArcObjects and Visual Basic for Application (VBA) programming languages in ArcGIS software. RIMIS can give information on the uniformity of water distribution and the shortfall or excess and what decisions to adopt for the next day. It ensures equal sharing of water for the tail-end users. The system helps to keep input and output databases always updated with respect to the real field conditions. The results are displayed on the computer screen together with colour-coded maps, graphs and tables in a comprehensible form. This will help irrigation managers to enhance decision-making in the management and operation of the irrigation system. The development of the overall system and procedures is illustrated with data from a study area.     

A systematic approach for estimating water losses in irrigation canals

In order to determine water losses in irrigation canals, a systematic approach was developed, consisting of two main components: a seepage simulation model and a hydraulic simulation model. The SEEP/W module of the Geo-Studio software was used to simulate the seepage rate, and the Hydrologic Engineering Center-River Analysis System (HEC-RAS) hydrodynamic model was used for hydraulic simulation. Different operation scenarios were designed to investigate all possible situations in daily operation of water distribution and delivery systems. The seepage simulation results show that the seepage losses were higher at the bottom and corners of the canal, because the hydraulic gradient was affected by the hydraulic load. The hydraulic simulation results show that due to physical and management infrastructure (using non-automated and operator-based regulation structures), operational losses accounted for a significant volume of losses compared to seepage losses. In most operation scenarios, the maximum seepage loss was 10%, and the remaining 90% was related to operational losses. It is concluded that any factor (decrease or increase of inflow to the canal) that causes an increase or decrease of operational losses is ultimately a determining factor in reducing or increasing total losses. Therefore, management approaches should be adopted to improve performance of the system and reduce losses, especially operational losses, by improving the operation methods of water level regulation and off-take structures.     

Simulation-Optimization Modeling for Conjunctive Use Management under Hydrological Uncertainty

The canal water supply, which is the only source of irrigation, in the rice-dominated cropping system of the Hirakud canal command (eastern India) is able to meet only 54 % of the irrigation demand at 90 % probability of exceedance. Hence, considering groundwater as the supplemental source of irrigation, conjunctive use management study by combined simulation-optimization modelling was undertaken in order to predict the maximum permissible groundwater pumpage from the command area. Further, optimal land and water resources allocation model was developed to determine the optimal cropping pattern for maximizing net annual return. The modelling results suggested that 2.0 and 2.3 million m³ of groundwater can be pumped from the bottom aquifer during monsoon and non-monsoon seasons, respectively, at 90 % probability of exceedance of rainfall and canal water availability (PERC). Optimal cropping patterns and pumping strategies can lead to about 51.3–12.5 % increase in net annual return from the area at 10–90 % PERC. The sensitivity analysis of the model indicates that the variation in the market price of crops has very high influence on the optimal solution followed by the cost of cultivation and cultivable area. Finally, different future scenarios of land and water use were formulated for the command area. The adoption of optimal cropping patterns and optimal pumping strategies is strongly recommended for sustainable management of available land and water resources of the canal command under hydrological uncertainties.     

Performance of Low Energy Water Application Device

Considering the overall farming situation in developing countries particularly India it has been observed that the available options of efficient irrigation technologies are unable to cover up small and marginal farm holders due to lack of the applicability and acceptability in terms of their needs, priorities and financial capabilities. This makes imperative to develop a substitute of existing technologies that could be cheap simple and less capital intensive as well as applicable for small farms. This paper discusses the performances of a low cost water and energy efficient device called LEWA which can be used in place of overhead impact sprinklers to irrigate field and row crops efficiently at small farms. LEWA can be operated at an operating pressure range 39 to 98 kPa at its nozzle head, with discharge rate 0.87–1.10 m³/h, and throw diameter 6–8 m. Since operating pressure at the nozzle head governs overall system pressure and reflects the total cost of the system, size of prime mover pump required and its operational cost; therefore the developed device holds greater promise in development of a cost effective water and energy efficient pressurized irrigation system for small and marginal farmers possessing small and fragmented land.     

Influence of roughness changes on offtaking discharge in irrigation canals

The paper shows how a change in irrigation canal roughness can influence the flow passing through offtakes. HEC-RAS steady state model was calibrated with changing Manning's “n” and used for flow simulation in a modern irrigation system in Iran. Results showed that the Manning's “n” obtained from the model calibration procedure (0.025) was different significantly from its primary value (0.015) along the canal. The increase was due to poor canal maintenance. The changes in roughness of about − 20%, − 40%, 40%, and 100% of the primary value can significantly influence the upstream water level and the discharge passing through some offtakes. In order to better evaluation and comparison of offtakes, sensitivity indicator “offtake sensitivity to roughness” was introduced. An analytical approach helped us to define an equation for direct estimation of the sensitivity indicator under steady state uniform conditions for trapezoidal canals. Evaluation of water level fluctuations and the sensitivity indicator shows that only two of the offtakes are sensitive to roughness changes because of being located at the upstream of submerged cross-regulators. It can be concluded that the effects of roughness changes could be more important for offtakes located far from the downstream cross-regulators or near the submerged cross-regulators.     

Optimal Design of Pressurized Irrigation Networks to Minimize the Operational Cost under Different Management Scenarios

The adoption of measures leading to higher efficiencies in the use of both water and energy in water distribution networks is strongly demanded. The methodology proposed combines a multi-objective approach and a financial analysis to determine de optimal design of pressurized irrigation networks which entails the minimization of both the investment cost and operational cost under three operating scenarios that incorporate energy saving strategies: 1- all hydrants operate simultaneously; 2- hydrants are grouped into sectors and irrigation turns are established; 3- the on-demand operation of the network is assumed. This methodology has been applied in a real irrigation network located in Southern Spain showing that the lowest overall design cost (investment and operational costs) is achieved in scenario 2. The comparison of the selected solutions in the three proposed scenarios with the current network design considering the total fulfillment of irrigation requirements showed that operational cost savings between 65% and 76% could be achieved.     

DSS Application to the Development of Water Management Strategies in Ribeiras do Algarve River Basin

Within the Project – “Developing Strategies for Regulating and Managing Water Resources and Demand in Water Deficient Regions (WSM)” funded by the EU in fifth Research Framework Program, the Ribeiras do Algarve River Basin was chosen as a case study to develop a DSS for planning purposes. Located in the southern stretch of the Portuguese territory, crucial conflicts do exist between tourist and agricultural water uses within the river basin. Additionally, there are important deficiencies in urban secondary water supply. Also inadequate irrigation methods and poor quality of water existing in some areas urge the implementation of management measures. Different ways to improve the water management situation were analysed: (a) structural options, (b) demand management options and (c) socio-economic measures. These options were analysed using a range of combinations of extreme demand and availability scenarios and ranked based on indicators reflecting the perception of the local stakeholders towards economic development and social and environmental sustainability. On a second phase, the formulation of strategies using the available options was addressed and two different strategies, resulting from a tentative timeframe of water management options combination, were applied aiming to achieve goals defined with regional stakeholders, namely: (a) on a first stage, the optimization of the domestic and irrigation water demand coverage and aquifer’s groundwater exploitation use ratio; (b) on a second stage, the determination of the water pricing increase necessary to achieve economical sustainability, aiming at cost recovery goals in accordance with the Water Framework Directive compliance.     

黄河下游灌区引黄灌溉需水预测关键技术分析

根据水量平衡原理,建立了黄河下游灌区引黄灌溉需水量中期预测方法。分析了引黄灌溉需水预测基本原理,阐述了作物需水量、有效降水量、斗渠以下灌溉水利用系数、引黄灌溉需水量分离等引黄灌溉需水预测的关键参数和方法。作物需水量可采用修订的Valiantzas方程进行预测;有效降水量预测可采用美国垦务局推荐方法;斗渠以下灌溉水利用系数可采用该系数与末级渠道灌溉控制单元至支渠分水口的距离、渠道衬砌率等的线性方程估算;引黄灌溉需水量的分离可采用高精度遥感技术确定引黄灌溉面积,并通过本文提出的计算方法,从灌区供水水源中分离出引黄供水需求量。上述关键技术问题的研究可以为黄河下游农业用水需求预测提供技术支持。     

Rehabilitation of Irrigation Distribution Systems: The Case of Jericho City

Efficiency enhancement in irrigation distribution system (IDS) contributes to substantial water savings. This paper aims to present the methodology and lessons learned from efforts to improve efficiency in the irrigation distribution system of Jericho City. This effort presents a new paradigm in water management in water scarce countries, which focuses on both supply and demand management rather than on supply augmentation. Converting the existing irrigation canal system to a pressurized pipe network carries out rehabilitation of IDS in Jericho City. Analysis of the new IDS is performed through computer simulation. Considerations and constraints for sustainable irrigation management are presented.     

Conjunctive Water Use Planning in an Irrigation Command Area

In the present study, an integrated soil water balance algorithm was coupled to a non-linear optimization model in order to carry out water allocation planning in complex deficit agricultural water resources systems based on an economic efficiency criterion. The LINGO 10.0, optimization package has been used to evolve at optimal allocation plan of surface and ground water for irrigation of multiple crops. The proposed model was applied for Qazvin Irrigation Command Area, a semi-arid region in Iran. Various scenarios of conjunctive use of surface and ground water along-with current and proposed cropping pattern have been explored. Some deficit irrigation practices were also investigated. The results indicate that conjunctive use practices are feasible and can be easily implemented in the study area, which would enhance the overall benefits from cropping activities. The study provides various possible operational scenarios of the branch canals of the command area in the common and dry condition, which can help managers in decision making for the optimum allocation plans of water resources within the different irrigation districts. The findings demonstrate that for deficit irrigation options, the mining allowance of ground water value of the command area is greatly reduced and ground water withdrawal may be also restricted to the recharge to maintain the river–aquifer equilibrium.     

Modeling the Athens water supply system

This paper presents an investigation of a real-world water-resources problem involving both planning and management aspects. The Athens water supply system is studied in order to assist its future operation and the design of alternative system-improving works. The yield of the existing system is first assessed via simulation. Then the risk of system failure to meet the water demand is evaluated for various water demand scenarios and operation policies, with emphasis on the 1989–90 critical situation. Alternative future reservoirs in the Evinos River Basin are studied by testing large number of technical solutions. Uncertainties on hydrology, leakage losses, water demand, and possible damages are taken into account. Finally, a computer programme is developed to assist the water supply policy design for the existing Mornos-Iliki system.     

簸箕李灌区泥沙远距离输送的研究

目前，引黄灌区渠道集中处理泥沙的模式已受到很大的限制，进一步研究分散处理泥沙的模式是非常必要的。本文在山东簸箕李灌区的基础上，分析水沙资料，总结灌区泥沙输送的经验。     

Feasibility Evaluation of Pressurized Irrigation in Canal Commands

India has one of the largest and most ambitious irrigation programme in the world with net irrigated area exceeding 47 million hectares. However, the overall project efficiency from the headwork to the farmer’s field has been quite low which leads to not only poor utilization of irrigation potential created at huge cost, but also aggravates the degradation of soil and water resources and thereby endangers the sustainability of agricultural production system. As the cost of creating additional irrigation potential in terms of financial, human and environmental aspects has increased tremendously, need of the hour is to increase the irrigation efficiency of existing projects and use saved water for irrigating new areas or meeting the demand of non-agricultural sector. The contribution of application efficiency to poor irrigation efficiency is quite high and therefore increasing application efficiency by a shift in application method from surface to pressurized system has potential of vastly improving irrigation efficiency. To evaluate feasibility of this concept, a pilot study was initiated at Water Technology Centre for Eastern Region, Bhubaneswar, on one outlet of a minor irrigation command. The system has been designed in such a way that it provides pipe conveyance and surface irrigation for rice cultivation during monsoon season and pressurized irrigation during post monsoon period through a hybrid system of sprinkler and drip with four outlets for sprinkler irrigating 2.8 ha area and two outlets for drip irrigating 1.9 ha area. The system is also capable of providing irrigation through drip to part of a command during summer for third crop using water stored in service reservoir after the canal is closed in first week of April. To take care of sediment in the canal water, there are three stages of filtration: first by hydrocyclone filter which filters heavy suspended materials viz. sand, silt, etc., then by the sand filter and finally by the screen filter. The filtration at three stages reduces the turbidity to the desired level. It has been found that three-stage filtration reduced the turbidity to two NTU which is within permissible limit. Considering the cost of water saved, a benefit-cost ratio of the system was found out to be 1.126. This B: C ratio can be further increased by increasing the productivity of the fish and papaya in service reservoir area and better crop management during summer season.     

新时期汾河灌区可持续发展的思考

汾河灌区在山西省农业和社会经济发展中具有重要的地位,文中分析灌区水资源、骨干水利工程状况、末级渠系管理与建设、信息化发展以及生态环境方面存在的问题,结合水利现代化的要求提出相应对策,阐述了通过调蓄塘库群系统建设、节水改造和续建配套工程、末级渠系改造、灌区公用信息平台开发以及创新农户参与灌溉管理组织形式等途径可实现汾河灌区的可持续发展。     

沈阳浑北灌区渠道水利用系数测定影响因素分析

测定渠道水利用系数,可以科学合理调配灌溉水源,实行计划用水。采用千米测流法与一条线测流法沈阳浑北灌区渠道水利用系数进行了测定。结果表明：砂性土壤和填方渠道的渠道水利用系数小,重壤土和挖方渠道的渠道水利用系数大;渠道越长,渠道水利用系数越小,渠道越短,渠道水利用系数越大;泡田时期渠道水利用系数小,补水时期渠道水利用系数大;渠道引水流量逐渐变小时,渠道水利用系数小;不同的施测方法得出的渠道水利用系数也不同。研究结果可为今后灌区水利建设规划、设计与施工提供科学依据。     

宁夏红寺堡扬黄灌区农业灌溉用水分析

通过对宁夏红寺堡扬黄灌区灌溉面积变化、用水水平、水量调配分析得出：2012年灌溉面积4．22万hm2．超出调概面积14．5％,粮食、经济作物、林草、其他作物灌溉比为5．1：2．7：1．3：0．9,2010－2012灌溉比例基本保持稳定．玉米在各干渠种植面积较大;2010－2012年灌溉用水5713m3／hm2,与设计灌溉定额基本一致,灌溉需水量随着灌溉面积的增加呈现线性增加,各泵站单位灌溉面积用水量差异显著（Sig〈0．05）;7月份灌溉引、用水量占比例最大,分别为24．8％～26．6％、25．3％-26．6％,冬灌引、用水量比例最小,分别为4．1％一6．0％、3．8％～5．7％。典型于渠在灌溉期内存在超出设计流量运行时段,对干渠用水安全造成隐患;红寺堡扬黄灌区存在总体规模超出设计规模、种植结构单一、管理自动化程度低、泵站实际提水量超出或低于设计提水量等问题。