Simulating Unsaturated Zone of Soil for Estimating the Recharge Rate and Flow Exchange Between a River and an Aquifer

Coupling surface water and groundwater models dynamically based on a simultaneous simulation of saturated and unsaturated zones of soil is a useful method for determining the recharge rate and flow exchange between a river and an aquifer as well as simultaneous operation of water resources systems. Thus, the main objectives of this study are to investigate the effects of surface water and groundwater interactions through their systematic simulation and to create a dynamic coupling between surface water and groundwater resources of the area by relevant mathematical models. Accordingly, hydrologic soil moisture method and MODFLOW model were employed to simulate the unsaturated and saturated zones, respectively. The results revealed that simultaneous simulation of the saturated and unsaturated zones of the soil can illustrate the interaction between surface water and groundwater at any spatial and temporal intervals well through using complete hydroclimatological balance components in the form of a coupled model. The application of this method in the Loor-Andimeshk Plain, located in the southwest of Iran, showed that aquifer recharge through the plain area from November to March is due to precipitation. On the other hand, in the warm months (June to September), the plain is merely fed through irrigation water penetration. As the level of river water in both Dez and Balarood rivers is higher than the Loor-Andimeshk aquifer level, hence the exchange occurs as a leakage from the river to the aquifer. The highest and lowest values of average exchangeable water in Balarood River occur in March and April and in Dez River are from June to September.

     

市场经济条件下农业水资源高效利用模型研究

本文提出了市场经济条件下农业水资源高效利用模型。这个模型可根据不同的水资源利用模式和区域经济发展模式,基于区域水资源开发利用状况和水土资源组合条件,合理组织农业生产的诸要素,通过市场经济中的价值杠杆,对灌区的各种土地利用规模、种植结构和灌溉制度等进行合理配置,使得该研究区内的农业水资源利用在3个方面得到了较好的改进:(1)在实现农业水资源高效利用过程中,充分考虑了农民收入水平的提高;(2)研究了水价变化对农业生产、农民收人和对井渠双灌的促进作用;(3)探讨了水价与各种节水措施之间的关系,以及不同水价条件下各种节水措施规模、节水量和投资效益的定量描述。     

水均衡法在区域地下水资源量评价中的应用研究

地下水资源是我国西北地区水资源的主要组成部分,对地下水资源全面科学的综合评价是解决水资源缺乏问题的基础性工作。详细阐述了区域地下水资源评价方法,水均衡法特点、基本原理及计算内容。通过收集资料,对西北某地区地下水资源进行了定量计算,为科学合理地利用地下水,保持水土平衡,促进该地区经济可持续发展提供了依据。     

GIS-Based Groundwater Management Model for Western Nile Delta

The limited availability of renewable fresh water is a major constraint on future agriculture and urban development in Egypt. The main water resource that Egypt has been depending on is the River Nile. Nowadays, the role of groundwater is steadily increasing and will cover 20% of the total water supply in the coming decades especially in the reclaimed areas along the desert fringes of the Nile Delta and Valley. Abstraction from groundwater in Egypt is dynamic in nature as it grows rapidly with the expansion of irrigation activities, industrialization, and urbanization. One of these areas is the Western Nile Delta in which the groundwater is exploited in many localities. To avoid the deterioration of the aquifer system in this area, an efficient integrated and sustainable management plan for groundwater resources is needed. Efficient integrated and sustainable management of water resources relies on a comprehensive database that represents the characteristics of the aquifer system and modeling tools to achieve the impacts of decision alternatives. In this paper, a GIS-based model has been developed for the aquifer system of the Western Nile Delta. The GIS provides the utilization of analytical tools and visualization capabilities for pre-and post-processing information involved in groundwater modeling for the study area. The developed model was calibrated for steady state and transient conditions against the historical groundwater heads observed during the last 20 yr. The calibrated model was used to evaluate groundwater potentiality and to test two alternative management scenarios for conserving the aquifer system in Western Nile Delta. In the first scenario, reducing the surface water inflow while increasing the annual abstraction from groundwater by about 450 million m³ and improving the irrigation system could increase the net aquifer recharge by about 5.7% and reduce the aquifer potentiality by about 91%. Constructing a new canal as a second management scenario could increase the annual aquifer potentiality by about 23%. The GIS-based model has been proven to be an efficient tool for formulating integrated and sustainable management plan.     

时间序列模型在北京西山地区岩溶地下水位预测中的应用

作为北京水资源储备区,北京西山地区地下水位动态变化对北京市水资源管理具有重大意义。时间序列模型是研究预测地下水水位动态变化特征的有效方法。为了解北京西山地区地下水位未来变化趋势,本文选用北京西山地区地下水位长观序列,通过拟合序列的趋势项、周期项及随机项分量,建立地下水位动态变化模型。模型精度检验表明模型拟合程度良好,预测结果显示西山地区未来五年内地下水位呈现动态平衡状态。     

Optimal Allocation of Resources for Increasing Farm Revenue under Hydrological Uncertainty

The formulation and application of two optimization models is presented in this study. The models were used to maximize the net farm revenue of an irrigated area located in northwest India by optimally allocating the available water and land resources. In order to moderate the rising water table issues, a ground water component was introduced in the model, while still ensuring optimal resources allocation. Results of the model indicates a reduction in barley, gram, mustard, and rice production area while at the same time an increase in sugarcane, millets, wheat, and cotton cultivation areas under optimal conditions. The ground water exploitation has increased in the model allocation, which consecutively moderated the rising water table problems. The model allocations has resulted in more than 31 % increase in net farm revenue. The proposed models can be employed as a dependable tool for making the decisions at local and regional levels and are capable of solving the rising water table issues of irrigated areas. The formulations proposed in this study are simple and can be employed anywhere for capitalizing on the farm revenue by moderating the water resources problems. The model constraints, though, be different considering the quality and quantity aspects of different water sources.

     

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.     

Management perspectives on a deep aquifer system for rural water supply in Olt and Vàlcea counties, Romania

The water supply in the Romanian counties of Olt and Vàlcea is mainly from groundwater from a deep aquifer system in Pliocene formations. Isotope analyses have been used to establish the supply area of the deep aquifer system. The age of the groundwater has been estimated for two samples by using ¹⁴C analysis. A simplified numerical model for a north–south cross‐section has provided global values for the hydraulic conductivity and effective porosity of the aquifer system. The groundwater from permeable horizons deeper than 120–140 m is highly mineralised and is, therefore, inappropriate for use as a water supply. Because groundwater resources are limited, the water supply for industry and domestic use in urban regions cannot increase too much. Thus, the deep aquifer system could also be used as a water supply for rural regions.     

Application of Neural Networks and Optimization Model in Conjunctive Use of Surface Water and Groundwater

This study develops an optimization model for the large-scale conjunctive use of surface water and groundwater resources. The aim is to maximize public and irrigation water supplies subject to groundwater-level drawdown constraints. Linear programming is used to create the optimization model, which is formulated as a linear constrained objective function. An artificial neural network is trained by a flow modeling program at specific observation wells, and the network is then incorporated into the optimization model. The proposed methodology is applied to the Chou-Shui alluvial fan system, located in central Taiwan. People living in this region rely on large quantities of pumped water for their public and irrigation demands. This considerable dependency on groundwater has resulted in severe land subsidence in many coastal regions of the alluvial fan. Consequently, an efficient means of implementing large-scale conjunctive use of surface water and groundwater is needed to prevent further overuse of groundwater. Two different optimization scenarios are considered. The results given by the proposed model show that water-usage can be balanced with a stable groundwater level. Our findings may assist officials and researchers in establishing plans to alleviate land subsidence problems.     

The Use of Participatory Object-Oriented Bayesian Networks and Agro-Economic Models for Groundwater Management in Spain

This paper describes the development of a participatory decision support system for water management in the Upper Guadiana basin in central Spain where there has long been competition for groundwater resources between the agricultural sector and the environment. In the last few decades the rapid development of irrigation has led to the over-exploitation of the Mancha Occidental aquifer, the main water source in the area; this in turn has led to the loss of ecologically important wetlands. Against this background the River Basin Authority (RBA) has designed a new water management plan aimed at reducing water consumption. The objective of this paper is to evaluate the impact of these measures on both the environment and the agricultural sector. To this end stakeholders have been invited to actively participate in the development of a decision support system (DSS) based on the combination of an agro-economic model and an object-oriented Bayesian network. This DSS has been used to evaluate the trade-off between agriculture and the environment for different management options at different scales. Results indicate that achieving even a partial recovery of the aquifer water levels will require strict enforcement by the RBA of water restrictions on farmers combined with a high offer price for the purchase of water rights. However, compliance with water restrictions inevitably leads to losses in farm income, especially in small vineyard farms, unless additional measures are taken to compensate for those potential losses. The purchase of water rights alone is insufficient to ensure the recovery of water levels; accompanying measures included in the new regional management plan will also need to be undertaken.     

The Effects of Groundwater and Surface Water Use on Total Water Availability and Implications for Water Management: The Case of Lake Naivasha, Kenya

This study discusses the effects of water abstractions from two alternative sources on the available water volume around Lake Naivasha, Kenya: the lake itself and a connected aquifer. An estimation of the water abstraction pattern for the period 1999–2010 is made and its effect on the available water volume in Lake Naivasha and its connected aquifer is evaluated using a simple water balance modeling approach. This study shows that accurate estimates of annual volume changes of Lake Naivasha can be made using a simple monthly water balance approach that takes into account the exchange of water between the lake and its connected aquifer. The amount of water that is used for irrigation in the area around Lake Naivasha has a substantial adverse effect on the availability of water. Simulation results of our simple water balance model suggests that abstractions from groundwater affect the lake volume less than direct abstractions from the lake. Groundwater volumes, in contrast, are much more affected by groundwater abstractions and therefore lead to much lower groundwater levels. Moreover, when groundwater is used instead of surface water, evaporation losses from the lake are potentially higher due to a larger lake surface area. If that would be the case then the overall water availability in the area is more strongly affected by the abstraction of groundwater than by the abstraction of surface water. Therefore water managers should be cautious when using lake levels as the only indicator of water availability for restricting water abstractions.     

A Decision Support System to Manage the Groundwater of the Zeuss Koutine Aquifer Using the WEAP-MODFLOW Framework

This paper describes the development of a Decision Support System (DSS) for groundwater management of the ‘Zeuss Koutine’ aquifer in southeastern Tunisia using the WEAP-MODFLOW framework. First, a monthly MODFLOW model was developed to simulate the behaviour of the studied aquifer. A conceptual model of the study area was designed and a WEAP schematic representing the real hydraulic system was developed. In addition to the studied aquifer, other water resources available in the region, such as desalination plants and groundwater, were taken into consideration in this DSS. Inputs to the hydrogeological model include natural recharge and inflow from higher neighbouring aquifers. Outputs are mainly agricultural, touristic and urban water consumption. It was shown that the DSS developed was able to evaluate water management scenarios up to 2030, especially future water consumption, transmission link flow and active cell heads of the MODFLOW model for each time step. Results for the Zeuss Koutine aquifer demonstrated that desalination plants already built in the cities of Jerba and Zarzis have contributed to decreasing the continuous drawdown observed before 1999. The use of a sea water desalination plant to supply Jerba and Zarzis in the future is a solution for reducing the Zeuss Koutine aquifer drawdown. Defining its optimal capacity over time poses a new research question.     

Multi-Objective Optimal Model for Conjunctive Use Management Using SGAs and NSGA-II Models

The widespread investigations on water resources management has become an essential issue because due to lack of sufficient research and inattention to planning and management of conjunctive use of surface and groundwater. The conjunctive management is a suitable alternative for imbalanced water resources distribution and related constraints in using of surface water. In this paper, a multi-objective model is developed to maximize the minimum reliability of system as well as minimize the costs due to water supply, aquifer reclamation and violation of the reservoir capacity in operation and allocation priority. The non-dominated sorting genetic algorithm (NSGA-II) is used to present the optimal trade-off between the objectives. The sequential genetic algorithms is also applied (SGA) in order to be compared with the NSGA-II model. The results show that the NSGA-II model can considerably reduce the computation burden of the conjunctive use models in comparison with the SGA optimization model. The obtained trade-off curve shows that a little increase in reliability leads to much more system costs. The weighted single objective SGA model results verify optimal trade-off obtained from NSGA-II model and show the optimality of allocated discharges.     

Distributed Simulation‐optimization Model for Conjunctive Use of Groundwater and Surface Water Under Environmental and Sustainability Restrictions

Evolving optimal management strategies are essential for the sustainable development of water resources. A coupled simulation-optimization model that links the simulation and optimization models internally through a response matrix approach is developed for the conjunctive use of groundwater and surface water in meeting irrigation water demand and municipal water supply, while ensuring groundwater sustainability and maintaining environmental flow in river. It incorporates the stream-aquifer interactions, and the aquifer response matrix is generated from a numerical groundwater model. The optimization model is solved by using MATLAB. The developed model has been applied to the Hormat-Golina valley alluvial stream-aquifer system, Ethiopia, and the optimal pumping schedules were obtained for the existing 43 wells under two different scenarios representing with and without restrictions on stream flow depletion, and satisfying the physical, operational and managerial constraints arising due to hydrological configuration, sustainability and ecological services. The study reveals that the total annual optimal pumping is reduced by 19.75?% due to restrictions on stream flow depletion. It is observed that the groundwater pumping from the aquifer has a significant effect on the stream flow depletion and the optimal conjunctive water use plays a great role in preventing groundwater depletion caused by the extensive pumping for various purposes. The groundwater contribution in optimal conjunctive water use is very high having a value of 92?% because of limited capacity of canal. The findings would be useful to the planners and decision makers for ensuring long-term water sustainability.

     

信息融合型页岩气开采区含水层富水性预测——以凤冈区块为例

页岩气在开采过程中不但容易污染地下水资源,而且还需要大量的水资源来保障水力压裂技术的用水量,因此预测页岩气开采区的地下水富水性对于合理保护和利用页岩气开采区的地下水资源具有重要的意义。在总结岩溶地区含水层富水性主要控制因素的基础上,利用层次分析方法(AHP)建立了融合多源信息的含水层富水性评价模型,确定了因素权重,然后利用地理信息系统(GIS)技术的信息处理和空间展示功能制作了各富水性影响因素专题图,并对各专题图进行了信息融合叠加,最终完成了凤冈页岩气开采区的含水层富水性评价预测。基于GIS技术的信息融合型含水层富水性评价方法可以有效地反映含水层富水性这一受控于多因素影响且具有非常复杂形成机理的非线性动力现象,可为页岩气开采区的地下水资源利用与保护提供依据。     

Multiobjective management of a contaminated aquifer for agricultural use

Planned utilization of groundwater from a contaminated aquifer requires development of management strategies that determine the spatial distribution of withdrawal for allocation, as well as for control of water quality. Minimization of groundwater allocation for different purposes, and the control of contamination in the aquifer by a specified pumping strategy constitute a management problem with two conflicting objectives. In order to demonstrate possible tradeoffs between water quality control objective and minimum groundwater withdrawal objective, a multiobjective optimization model is formulated. The solution of the model specifies a strategy to control pollution distribution in the aquifer as per agricultural needs, and also evolve an optimal allocation policy to statisfy agricultural demands. Pareto-optimal solutions representing the tradeoff between the two noncommensurate objectives are established. The formulated model uses the embedding technique for simulating the flow and the transport processes in the aquifer. The constraint method is used to transform the multiobjective optimization model into a single objective optimization model. The resulting model is solved using the exterior penalty function method in conjunction with the Hooke-Jeeves method. The proposed model is easily adoptable for various agroclimatic regions and cropping patterns. For illustrative purposes, the model is applied to a specified study area. Although solutions of the model are presented and discussed as per agricultural requirements in terms of both quality and quantity, solutions for other kinds of water demands can be obtained using the same model with minor modifications. Results show that an optimal pumping strategy can be effectively utilized for controlling contamination in the aquifer.     

陡河流域地表水与地下水转化关系

通过对陡河流域地表水-地下水水样的氢氧同位素分布特征进行分析,发现研究区河岸带第Ⅰ含水层除了受大气降水、灌溉回归水入渗补给外,还接受河水早期的渗漏补给,第Ⅱ含水层对第Ⅲ含水层有越流补给,第Ⅱ含水层同时也受大气降水和灌溉回归水的影响,而远离河岸带的第Ⅳ含水层与上覆各含水层稳定同位素组成显著不同,河岸带水库附近的第Ⅳ含水层可能受地表水库渗漏影响。河岸带地下水与地表水水力联系的变迁严格受河岸带地下水水位变化控制,如景庄子剖面的地下水埋深为5m,雨季时河水补给地下水,旱季时地下水补给河水,而靠近地下水漏斗中心的越河乡剖面地下水水位埋深达25m,其常年受地表水补给。     

塔里木河流域中游绿洲地下水资源评价——以沙雅县为例

地下水资源是我国西部地区水资源的主要组成部分,对地下水资源全面科学的调查和评价,是解决水资源问题的基础性工作。本文尝试采用水均衡方法的同时进行数值模拟的方法对塔里木河流域中游绿洲沙雅县地下水水资源进行评价。结果表明:通过地下水资源均衡计算,绿洲地下水处于正均衡状态,通过数值模拟法计算,绿洲地下水处于负均衡状态。水均衡方法对较大区域地下水资源评价方便易行,但是局部地区精细化计算能力不足,由于多数补给项采用补给系数法计算,结果误差偏大;数值模拟方法对各种尺度研究区均可以进行模拟计算,但是对已有基础资料要求较高,模拟过程充分考虑实际水文地质条件及地下水位动态拟合精度,各源汇项计算精度优于水均衡评价方法结果。两种方法结合应用可更好地用于地下水资源评价。对沙雅县的地下水资源进行评价和分析,目的是科学合理开发利用地下水,保持水土平衡,促进沙雅县经济可持续发展。     

Regional Water Balance and Economic Assessment as Tools for Water Management in Coastal Lebanon

The Lebanese coast is highly subject to seawater intrusion and groundwater deterioration. The study is carried out in Byblos district (Jbeil Caza) 35 km north of Beirut. It aims to investigate the seawater intrusion, to determine the regional water balance of the region and finally to estimate the economic value of that water for agricultural use. The monitoring of the aquifer was achieved through samples from different wells chosen randomly. As for the regional water balance, it was determined with use of a GIS model. The economic evaluation was carried out, using the contingent valuation method to estimate the willingness to pay of farmers to contribute to the improvement of groundwater quality; two alternative scenarios were proposed and compared with the current situation. The annual regional water balance is positive, which means that the region is rich in water. The monitoring results show that the coastal part of the region is slightly contaminated by seawater intrusion due to the excess of pumping from the aquifer. The economic evaluation estimated that farmers would contribute by 102 US$ yr^− 1 for the first proposal and 166.67 US$ yr^− 1 for the second.