Estimating Groundwater Withdrawal in Poorly Gauged Agricultural Basins

A method is presented for estimating the annual groundwater withdrawal based on water balance resulting from surface and groundwater hydrological considerations. The unknown groundwater losses of the aquifer are estimated from the groundwater level fluctuations, the specific yield and the groundwater withdrawal prior to the installation of the irrigation network. The meteorological and hydrometric data are used in the Sacramento hydrological conceptual model for the estimation of the stored groundwater volume, via minimization of the difference between the simulated and measured stream discharge. Following the installation of the network due to poorly kept field records, an initial estimation of the groundwater withdrawal is made based on the fluctuations of the groundwater level, the specific yield, and the annual precipitation. The monthly stored groundwater volume is verified against the volume obtained during the recharge of the basin (November–April). The difference between the groundwater volume and the measured discharge of the basin (May–October) is in agreement with the initial estimation of the groundwater withdrawal. This method is applied successfully in an agricultural basin on the island of Crete, Greece and its novelty lies in the fact that it can be used in basins where groundwater withdrawal is not known or data is incomplete.     

Cost-effective Approaches for Sustainable Groundwater Management in Alluvial Aquifer Systems

The consequences of unsustainable use of groundwater are becoming increasingly evident worldwide, particularly in developing nations. Groundwater management is a serious problem in many parts of the world. The prime concern is how to achieve groundwater sustainability. Artificial recharge techniques coupled with water harvesting hold a great promise for groundwater sustainability. The main intent of this paper is to highlight salient cost-effective and easy-to-use methods for augmenting groundwater resources in the alluvial hydrogeologic setting. Based on the intensive field investigation in a groundwater basin of Japan, three low-cost and easy-to-implement recharge techniques are suggested for alluvial aquifer systems, viz., augmentation of river flow, recharge through irrigation/drainage canals, and recharge from paddy fields. The source of recharge water for these recharge techniques is surface water supply. The efficacy of these methods or approaches has been demonstrated. It is emphasized that such cost-effective methods of groundwater recharge are key to sustainable groundwater management in both developing and developed countries. These methods must not be overlooked in the midst of sophisticated and highly expensive methods.     

Estimating Regional Groundwater Recharge Using a Hydrological Budget Method

Estimating groundwater recharge is a key component in determining the sustainable yield of groundwater resources in arid and semi-arid areas such as southern California. Estimating groundwater recharge on a regional scale requires developing a water budget that incorporates data on boundary conditions, aquifer properties, groundwater levels, and groundwater production. The hydrological budget method proposed herein is simple, cost-effective, and easy to apply. It utilizes matched pairs of groundwater level measurements, groundwater extraction data, and distributed specific yield information for estimating groundwater recharge. In this method, ARCGIS 9.0 Geostatistical and Spatial Analyst applications are used for interpolating/extrapolating and creating grids for specific yield, bedrock elevation, and raw groundwater data. The annual average groundwater recharge for the Hemet subbasin in western Riverside County, California, from 1997 to 2005 is estimated at 12.5 MCM, with wet and dry periods ranging between 14.9 MCM and 11.7 MCM, respectively. The proposed method utilizes information commonly available to most groundwater management entities, such as groundwater production data, groundwater level measurements, and lithologic information.     

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.     

开采浅层水 增雨水入渗 引河水补源 水可持续用

南皮县淡水资源严重短缺,制约工农业与经济社会的发展。春季开采浅层地下水包括微咸水和半咸水抗旱灌溉,腾出地下含水层空间；汛期增加降雨入渗,减少径流流失,防渍防涝,把时空分布不均的天然降雨转化为地下水资源；秋冬利用河道沟渠引蓄河水补源,淡化地下水质,增加地下水可采量。地上水地下水联合运用,保持水资源采补平衡。实现旱涝碱咸综合治理、水资源可持续利用与经济社会可持续发展。     

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。     

Impact of Urbanization on the Hydrology of Ganga Basin (India)

Large scale emigrations from rural areas to urban areas and population growth have been uninterrupted and accelerating phenomena in parts of Ganga basin, where urbanization is increasing at an unprecedented rate. Urban agglomeration is causing radical changes in groundwater recharge and modifying the existing mechanisms. Majority of the cities are sited on unconfined or semi confined aquifers depend upon river water and groundwater for most of their water supply and disposal of most of their liquid effluents and solid residues to the rivers and ground. There has also been an inevitable rise in waste production. Drainage of surface water has been disrupted as the small natural channels and low lying areas have been in filled, often with municipal waste. Total water potential of the Ganga basin including surface water potential and ground water potential is around 525.02 km³ and 170.00 km³ respectively. Basin supports approximately 42% of the total population in India. Water tables are declining at approximately an average of 0.20 m per year in many parts of the basin and there is a trend of deteriorating groundwater quality. The demand of water has been increased many folds and most of the areas are highly reliant upon the groundwater to meet this increasing demand for water, but unfortunately degradation of groundwater both in terms of quantity and quality has deteriorated the situation. Studies shows that change in climate may increase temperature by 2 to 6°C and can reduce precipitation up to 16%, which could reduce the groundwater recharge by 50%. In densely populated Ganga basin urban drainage consumes a high proportion of the investments into urban infrastructure and needs integrated approach for the sustainable development of water management, water education regarding conservation and pollution caused by urbanization.     

西辽河流域平原区地下水动态补给研究

基于分布式水循环模拟模型MODCYCLE,建立强人类活动影响下西辽河流域水循环模拟模型,量化西辽河平原地下水补给组成,分析地下水动态补给情况及年际、年内变化。分析结果表明：西辽河流域平原区地下水补给以降水入渗补给为主,与年降水量直接相关。随降水减少,降水入渗补给比重减少,河道入渗补给及灌溉回归补给比重增加。地下水补给的年内变化差异较大,且与年内降水分布直接相关。研究结果可为西辽河平原地下水资源可持续开发利用提供依据     

Development of a Rainfall-Recharge Relationship for a Fractured Basaltic Aquifer in Central India

Groundwater being an important component of the hydrological cycle, estimation of its annual replenishment is essential to evolve a plan for optimum utilization. Groundwater balance approach, which is used extensively for the quantification of recharge and discharge components has been adopted for the rainfall-recharge estimation. Various inflow and outflow components have been identified and estimated for Sagar block in Sagar district of Madhya Pradesh, which faces acute water scarcity and continuous decline in groundwater levels. The computed recharge from rainfall varies between 122.45 and 183.71 MCM. The computed rainfall-recharge is compared with the Chaturvedi (1973), Kumar and Seethapathi (2002), Krishna (1987), and U.P. Irrigation Research Institute models. Models have also been developed to estimate rainfall-recharge for varying ranges of the annual rainfall and have been compared with the existing models. The relative error in estimation of rainfall-recharge from proposed models varies between 0.03 and 9.24%. The overall scenario is net decline in groundwater storage to an extent of ?31.31 MCM over a period of 16 years from 1985–1986 to 2000–2001. The trend analysis by Kendall’s rank correlation test, regression test for linear trend and Mann–Kendall test also clearly suggests falling trends in groundwater storage at 5% significant level, thereby demonstrating over-exploitation of the groundwater aquifer. This has subsequently led to progressive decline in groundwater table in the study area. Efforts should be initiated to tap the surface water by creating storages at suitable sites and artificial recharge practices should be encouraged after identifying suitable recharge zones. Conjunctive use of the surface and groundwater along with water conservation practices and groundwater management measures should be taken up to arrest the progressive decline in groundwater levels and over-exploitation of groundwater aquifer.     

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.

     

An Analytical Solution of Boussinesq Equation to Predict Water Table Fluctuations Due to Time Varying Recharge and Withdrawal from Multiple Basins, Wells and Leakage Sites

Recharging and pumping are the integral part of any scheme of ground water resources development and both processes significantly affect the dynamic behavior of the aquifer system. Leakage from the aquifer’s base, if present, is other process which affects the water table variation. Therefore, an accurate estimation of water table fluctuation induced by recharging, pumping and leakage is pre-requisite to ensure sustainability of groundwater resources. In the present work an analytical solution of a 2-D linearized Boussinesq equation is developed to predict water table fluctuations in the presence of time varying recharge, pumping and leakage from any number of recharge basins, wells and leakage sites of any dimension for any number of recharge and pumping cycles. The rate of time varying recharge (or pumping) is approximated by using a series of linear elements of different lengths and slopes which are dependent on the nature of variation in the recharge (or pumping) rate. Application of the solution in the prediction of water table fluctuation in the presence of time varying recharge, pumping and leakage is demonstrated with the help of a numerical example. These numerical results indicate significant effect of the time varying recharge/pumping rates and leakage on the water table variation. Such information is useful for the proper management of groundwater.     

Management of Alluvial Aquifers in Two Southern African Ephemeral Rivers: Implications for IWRM

This paper summarises innovative research into the assessment of long-term groundwater recharge from flood events in dryland environments of the Kuiseb (Namibia) and the Buffels (South Africa) rivers. The integrated water resource management (IWRM) policies and institutions affecting the exploitation of groundwater resources in each of these developing countries are compared. The relatively large alluvial aquifer of the Kuiseb River (～240 Mm³) is recharged from irregular floods originating in the upper catchment. Reported abstraction of 4.6 Mm³ per year is primarily consumed in the town of Walvis Bay, although the groundwater decay (pumping and natural losses along the period 1983–2005) was estimated in 14.8 Mm³ per year. Recharge is variable, occurring in 11 out of 13 years in the middle Kuiseb River, but only in 11 out of 28 years in the middle-lower reaches. In contrast, the Buffels River has relatively minor alluvial aquifers (～11 Mm³) and recharge sources derive from both lateral subsurface flow and floodwater infiltration, the latter limited to a recharge maximum of 1.3 Mm³ during floods occurring once every four years. Current abstractions to supply the adjacent rural population and a few small-scale, irrigated commercial farms are 0.15 Mm³ yr^???1, well within the long-term sustainable yield estimated to be 0.7 Mm³ yr^???1. Since independence in 1990, Namibia’s water resource management approach has focussed on ephemeral river basin management of which the Kuiseb Basin Management Committee (KBMC) is a model. Here, some water points are managed independently by rural communities through committees while the national bulk water supplier provides for Walvis Bay Municipality from the lower aquifers. This provides a sense of local ownership through local participation between government, NGOs and CBOs (community-based organisations) in the planning and implementation of IWRM. Despite the potential for water resource development in the lower Buffels River, the scope for implementing IWRM is limited not only by the small aquifer size, but also because basin management in South Africa is considered only in the context of perennial rivers. Since 2001, water service delivery in the Buffels River catchment has become the responsibility of two newly created local municipalities. As municipal government gains experience, skills and capacity, its ability to respond to local needs related to water service delivery will be accomplished through local participation in the design and implementation of annual ‘integrated development plans’. These two case studies demonstrate that a variety of IWRM strategies in the drylands of developing countries are appropriate depending on scales of governance, evolving policy frameworks, scales of need and limitations inherent in the hydrological processes of groundwater resources.     

王赫生，李燕，周锴锷，张庆

为系统了解沙颖河流域地下水含水系统的补给源以及水化特征,在取样测试、现场监测的基础上,分别采用同位素、水文地球化学等方法,深入分析了沙颍河流域地下水含水系统特征。研究发现：沙颖河流域浅层地下水水化学类型自流域上游到下游呈HCO3-Ca+Mg型向HCO3+Cl-Ca+Mg型变化的趋势,中深层水以HCO3-Na型为主,局部呈HCO3+Cl型可能是浅层水混入的结果。采用铀不平衡方法识别地下水补给源,结果表明：浅层地下水补给源除降水外,还包括深层地下水的贡献;深层水来源包括大气降水、潜水和深层地下水3个补给源。各方法所得结论互相验证,研究结果可为流域内水循环模式研究、水污染防治等提供科学依据。     

Optimum Abstraction of Groundwater for Sustaining Groundwater Level and Reducing Irrigation Cost

Adaptation to increasing irrigation cost due to declination of groundwater level is a major challenge in groundwater dependent irrigated region. The objective of this study is to estimate the optimum abstraction of groundwater for irrigation for sustainable management of groundwater resources in Northwest Bangladesh. A data-driven model using a support vector machine (SVM) has been developed to estimate the optimum abstraction of groundwater for irrigation and a multiple-linear regression (MLR)-based model has been developed to estimate the reduction of the irrigation cost due to the elevation of the groundwater level. The application of the SVM model revealed that the groundwater level in the area can be kept within the suction lift of a shallow tube-well by reducing pre-monsoon groundwater-dependent irrigated agriculture by 40%. Adaptive measures, such as reducing the overuse of water for irrigation and rescheduling harvesting, can keep the minimum level of groundwater within the reach of shallow tube-wells by reducing only 10% of groundwater-based irrigated agriculture. The elevation of the groundwater level through those adaptive measures can reduce the irrigation cost by 2.07 × 10³ Bangladesh Taka (BDT) per hectare in Northwest Bangladesh, where the crop production cost is increasing due to the decline of the groundwater level. It is expected that the study would help in policy planning for the sustainable management of groundwater resources in the region.     

太湖地区典型小流域地下水储量动态模拟与分析

对太湖地区典型小流域的近地表地质特征进行系统野外试验,分析近地表土层土壤和岩层结构特征,初步确定了含水层计算参数;采用三维地下水流数值模拟方法概化水文地质条件,识别与验证模型参数。结果表明:地表水补给地下水的量约是地下水补给地表水总量的2倍,山溪型小流域的地表地下水交互过程趋于单向交换,即河道水补给地下水。从含水层储水量变化看,除去蒸散发,通过地下通道流失的水量占据总水量的相当比重,且地下储水的减少量主要依赖降雨入渗进行补给。所建立的模型能够较好地反映研究区实际的水文地质条件,揭示地表水和地下水的交互量的变化过程,并定量研究流域水量平衡动态关系,可为变化环境下的地下水保护和滨湖区的地下水潜流计算研究提供预测分析依据。     

Statistical Approach for Comprehensive Planning of Watershed Development Through Artificial Recharge

The purpose of the study is to demonstrate that cross-correlation analyses can contribute to the artificial recharge study in regional level of shallow aquifer. Correlations between hydrologic time series data were analyzed to identify the hydrogeologic location for potential artificial recharge in district Surat, Gujrat, India. The natural groundwater-level fluctuations and rainfall data were used for the analyses. The effective development of groundwater resources is essential for a country like India. India receives a good amount of average annual rainfall (114?cm) but most of its part goes waste as runoff. Over exploitation of groundwater due to increasing population is an additional cause of water crisis that results in the reduction in per capita availability of water in the country. Artificial recharge is essential for effective development of groundwater resources. An effort has been made to evaluate the suitable recharge zone considering rainfall by arresting runoff to restore groundwater conditions using a statistical technique. Groundwater system in a basaltic terrain where the top weathered regolith forms shallow aquifer the water table variation is directly influenced with temporal rainfall variation. Understanding of this relation is of critical importance to management of groundwater resources. A diagnostic relationship between recharge time series and water level time series is used to serve the purpose to determine the best site for groundwater recharge.     

Process Based Integrated Models for Managed Aquifer Recharge and Aquifer Storage Treatment and Recovery

Water Resources Management - Process based semi-analytical models for surface and ground water management of a recharge basin, based on the concept of managed aquifer recharge (MAR) and aquifer...     

A Generalized Predictive Model of Water Table Fluctuations in Anisotropic Aquifer Due to Intermittently Applied Time-Varying Recharge from Multiple Basins

Mathematical models play a key role in assessing the future behavior of a groundwater system in response to various schemes of ground water resources development such as artificial recharging and in selecting an appropriate one out of many proposed schemes for its sustainable development. This paper presents an analytical solution of groundwater flow equation for unconfined, anisotropic, 2-D rectangular aquifer under the Boussinesq approximation to predict water table fluctuations in the aquifer in response to general time-varying intermittent recharge from multiple rectangular infiltration basins of different spatial dimensions. The horizontal anisotropy incorporated in the model is such that the principal axes of the hydraulic conductivity tensor are oriented parallel to the rectangular sides of the aquifer. The time-varying recharge rate is approximated by a series of line elements of different lengths and slopes depending on the nature of variation of recharge rate. The solution is obtained by using extended finite Fourier sine transform. Application of the solution is demonstrated with the help of synthetic examples. Numerical results of the analytical solutions are verified by comparison with the results obtained from MODFLOW. Numerical results indicate significant effect of anisotropy in hydraulic conductivity on the nature of water table variation.     

Design of Managed Aquifer Recharge for Agricultural and Ecological Water Supply Assessed Through Numerical Modeling

The Walla Walla Basin, in Eastern Oregon and Washington, USA, faces challenges in sustaining an agricultural water supply while maintaining sufficient flow in the Walla Walla River for endangered fish populations. Minimum summer river flow of 0.71 m³/s is required, forcing irrigators to substitute groundwater from a declining aquifer for lost surface water diversion. Managed Aquifer Recharge (MAR) was initiated in 2004 attempting to restore groundwater levels and improve agricultural viability. The Integrated Water Flow Model (IWFM) was used to compute surface and shallow groundwater conditions in the basin under water management scenarios with varying water use, MAR, and allowable minimum river flow. A mean increase of 1.5 m of groundwater elevation, or 1.5 % of total aquifer storage, was predicted over the model area when comparing maximum MAR and no MAR scenarios where minimum river flow was increased from current level. When comparing these scenarios a 53 % greater summer flow in springs was predicted with the use of MAR. Results indicate MAR can supplement irrigation supply while stabilizing groundwater levels and increasing summer streamflow. Potential increase in long-term groundwater storage is limited by the high transmissivity of the aquifer material. Increased MAR caused increased groundwater discharge through springs and stream beds, benefiting aquatic habitat rather than building long-term aquifer storage. Judicious siting of recharge basins may be a means of increasing the effectiveness of MAR in the basin.     

Simulating Future Groundwater Recharge in Coastal and Inland Catchments

Groundwater is a primary source of drinking water in the Mediterranean, however, climate variability in conjunction with mismanagement renders it vulnerable to depletion. Spatiotemporal studies of groundwater recharge are the basis to develop strategies against this phenomenon. In this study, groundwater recharge was spatiotemporally quantified using the Soil and Water Assessment Tool (SWAT) in one coastal and one inland hydrological basin in Greece. A double calibration/validation (CV) procedure using streamflow data and MODIS ET was conducted for the inland basin of Mouriki, whereas only ET values were used in the coastal basin of Anthemountas. Calibration and simulation recharge were accurate in both sites according to statistical indicators and previous studies. In Mouriki basin, mean recharge and runoff were estimated as 16% and 9%, respectively. In Anthemountas basin recharge to the shallow aquifer and surface runoff were estimated as 12% and 16%, respectively. According to the predicted RCP 4.5 and 8.5 scenarios, significant variations in groundwater recharge are predicted in the coastal zone for the period 2020–2040 with average annual recharges decreasing by 30% (RCP 4.5) and 25% (RCP 8.5). Variations in groundwater recharge in the inland catchment of Mouriki were insignificant for the simulated period. Anthemountas basin was characterized by higher runoff rates. Groundwater management in coastal aquifers should include detailed monitoring of hydrological parameters, reinforced groundwater recharge during winter and reduced groundwater abstraction during summer depending on the spatiotemporal distribution of groundwater recharge.