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.     

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。     

Post Audit Analysis of a Groundwater Level Prediction Model in Developed Semiconfined Aquifer System

This paper assesses groundwater recharge under conditions of long-term groundwater pumping at the Ravnik pumping site in Croatia and analyses the groundwater level prediction model used in prior aquifer modelling. The results of model calibration revealed a very low net infiltration rate at the start of the pumping site’s operation. As the operation continued, the net infiltration rate slowly increased, while the percentage of infiltrated rainfall scaled up with increasing pumping rates. The predicted recharge of the covering aquitard amounts approximately 14–15 % of the mean annual precipitation. The aquifer recharge takes place from aquitard by seepage. A subsequent simulation of the pumping site’s operation was performed for the 9 years period on the assumption that the pumping rates and the groundwater recharge would be the same as those recorded during the final calibration years. Results show that the post audit measured levels correspond relatively well to the predicted levels and that increasing of the pumping rate causes changes in the water budget in advantage of net groundwater recharge as a consequence of spreading recharge area outside of previous model boundaries.     

石川河河谷区地下水人工补给潜力与补给方式

为实现石川河地下水位的有效回升进而维持采补平衡,需在该区实施地下水人工补给工程,并确定合理的 补给位置及有效的补给方式。选取地下水埋深、坡度、含水层厚度、含水层渗透系数、与环境敏感区距离和给水 度 6 个指标,运用空间分析技术对人工补给地下水地点适宜性进行评价;在此基础上建立三维地质模型分析典型 人工补给潜力区的地层结构,探索可行的地下水人工补给方式。结果表明：适宜进行人工补给的高潜力和较高潜 力区域主要分布在研究区中部及东南部,面积达 48.01?km2,占研究区总面积的 32.0%。建议：在石川河河道中上 游高潜力和较高潜力区域的北部修建地表入渗池或渗坑;在河道中上游高潜力和较高潜力区域南部和河道中下 游的较高潜力区域布设反滤回灌井群;可沿石川河河道中上游高潜力与较高潜力区域之间布置一条长约 4.5?km 的渗渠,利用河道进行入渗补给。研究结果可为地下水库的修建提供参考。     

油气田区承压含水层地下水污染机理及其脆弱性评价

根据研究区地质构造及水文地质概况，分析了研究区承压含水层地下水有机污染的机理，建立了针对该地区承压含水层地下水污染脆弱性评价指标体系，并应用神经网络技术作为评价体系中参数的赋权方法；由ANN与GIS耦合技术得到的研究区承压含水层地下水污染脆弱性区划图比较好地符合研究区的实际情况。     

Groundwater Level Forecasting in a Shallow Aquifer Using Artificial Neural Network Approach

Forecasting the ground water level fluctuations is an important requirement for planning conjunctive use in any basin. This paper reports a research study that investigates the potential of artificial neural network technique in forecasting the groundwater level fluctuations in an unconfined coastal aquifer in India. The most appropriate set of input variables to the model are selected through a combination of domain knowledge and statistical analysis of the available data series. Several ANN models are developed that forecasts the water level of two observation wells. The results suggest that the model predictions are reasonably accurate as evaluated by various statistical indices. An input sensitivity analysis suggested that exclusion of antecedent values of the water level time series may not help the model to capture the recharge time for the aquifer and may result in poorer performance of the models. In general, the results suggest that the ANN models are able to forecast the water levels up to 4 months in advance reasonably well. Such forecasts may be useful in conjunctive use planning of groundwater and surface water in the coastal areas that help maintain the natural water table gradient to protect seawater intrusion or water logging condition.     

地下水人工回灌和停采对地面沉降控制的影响分析

地面沉降是全世界主要的工程地质灾害之一,而地下水超采是造成地面沉降的主要原因之一。为研究地下水人工回灌和停采对北京平原地面沉降的影响,采用三维地下水模型和情景设计法,设计3个情景(保持现状、人工回灌和地下水停采)对北京平原区域及沉降中心的沉降速率进行模拟。结果表明:保持现状、人工回灌和地下水停采等情景下北京平原在2015、2020和2030年的区域地面沉降分别为24 mm/a左右、12. 7～23. 2 mm/a及12. 4～23. 7mm/a,沉降中心地面沉降分别为39. 30～158. 62 mm/a、21. 09～165. 83 mm/a及16. 5～162. 95 mm/a;人工回灌和地下水停采对研究区地下水水位和含水层储存量的恢复以及地面沉降的控制有显著的促进作用,但地下水停采的效果要优于人工回灌的效果;只有综合考虑社会经济发展和地面沉降控制,才能既控制地面沉降的恶化,又保证北京平原社会的可持续发展。     

不同回灌补源模式下石川河富平地下水库数值模拟

石川河富平地区地下水长期处于采补失衡状态,大范围含水层被疏干,形成区域性降落漏斗,针对拟建的石川河富平地下水库,设置5种开采回灌方案,建立地下水流数值模型模拟不同方案下地下水库水位和蓄水库容变化情况。结果表明：各回灌方案在消除降落漏斗的同时,均能较好地恢复地下水水位,且不超过地下水库的调蓄上限水位;回灌量相同、回灌方式不同时,逐日回灌方式的水位恢复效果优于灌期+非灌期回灌方式,较2018年地下水水位平均抬升13.55 m,蓄水库容增加2.99×10⁸ m³;回灌量不同时,较大回灌量对地下水水位的影响大于回灌方式,即泾惠渠水源回灌时,水位抬升程度最大,为19.77 m,蓄水库容相应增加4.36×10⁸ m³。模拟结果可为地下水库的调蓄与运行提供参考。     

Optimization of recharge and pumping rates by means of an inverse 3D model

The paper concerns the optimization of pumping and artificial recharge rates under hydraulic head constraints. This optimization is accomplished by means of an inverse three-dimensional (3D) model which is a combination of a numerical model, sensitivity analyses and nonlinear regression. The optimization criterion used is the minimization of the sum of the squares between the calculated and the desired water table maps. These maps were established for the end of each month of the period from December to August so that the annual average flux is outward from the modeling area. This outward flux will push back the salt water intrusion. The assumed natural recharge rates of the different months equal the mean values of the period 1958–1977. The aquifer parameters describing the water conducting and storing properties are also required as input data as well as the initial hydraulic heads. The optimized parameters are the artificial recharge rates of the months December, January, February and March and the pumping rates of the months April, May, June, July and August. For the first-mentioned months, the pumping rates are considered as known. During the last-mentioned period, no artificial recharge is possible. A unique solution is obtained. To check the optimized rates, a water balance is made. With this balance, it is shown that the treated phreatic aquifer can be used as a subterranean reservoir to store water that is abundantly present in the winter until the summer when water demand is large. It is also proved that the salt-water intrusion can be stopped by the temporal storage of the artificial recharged water.     

滨海深部含水层地下水排泄量评估

为了进一步计算评估滨海深部含水层地下水排泄量,以一个海底深部承压含水层系统为例,包括承压含水层及上覆弱透水含水层(海底),在内陆补给上考虑了与时间无关的年平均补给(常数)和由季节性降雨引起的周期性补给两种情况,从而建立了一个描述承压含水层中海底地下水排泄的数学模型,并得到其解析解。继而利用解析解分析了位于美国南大西洋Onslow海湾的SGD。结果显示,SGD排泄宽度变化范围为0.5~3.0 km,在承压含水层中海岸线处高于平均海平面1.0 m的水头值,其所产生的SGD速率为1.1~10.0 m2/d。     

天山北坡经济带东段浅层地下水固有脆弱性评价

基于改进的DRASTIC方法,选择地下水埋深、含水层净补给量、含水层岩性、土壤介质类型、地面坡度、浅层地下水水质、包气带介质类型、含水层渗透系数和潜水蒸发量9项评价指标,分别确定其评分体系和权重体系,并利用Arc Gis 10.2中的图层空间叠加分析功能,对天山北坡经济带东段地区的浅层地下水固有脆弱性进行评价。结果表明:脆弱性较高区和中等区占研究区总面积的80.17%,地下水整体脆弱性偏高,而导致研究区浅层地下水脆弱性偏高的主要因素为地下水埋深较小、含水层渗透性较强、浅层地下水水质差。     

第二松花江流域平原区浅层地下水脆弱性时变特征分析

以第二松花江流域平原区为研究区,选择了地下水埋深、净补给量、含水层介质、土壤介质、地形坡度、包气带影响、渗透系数7个指标,运用DRASTIC评价方法对浅层地下水脆弱性进行了评价,进一步分析了地下水脆弱性评价结果的影响因素。结果表明:(1)地下水脆弱性分区在整体上具有空间分带特征性,并与地貌分区具有良好的一致性,其中河谷平原区由于地下水埋藏较浅,地下水脆弱性较高,污染风险大;(2)受地下水位变动以及净补给量的影响,具体地段的地下水脆弱性等级也具有较为明显的年际与年内变化特征,但整体区域上的地下水脆弱性的相对级别仍受地貌格局的控制。在开展区域地下水脆弱性评价时,应注意选择具有代表性的时段数据进行评价。     

Quantifying natural recharge characteristics of shallow aquifers in groundwater overexploitation zone of North China

To improve the accuracy of hydrological simulations in the groundwater overexploitation zone of North China, it is necessary to study the characteristics of shallow aquifer recharge on daily scale. Three shallow aquifer recharge indices were used to quantify shallow aquifer recharge in two ways. The recharge coefficient was used to quantify the amount of shallow aquifer recharge. The recharge duration and water table rise coefficient were used to quantify the recharge temporal process. The Spearman rank correlation coefficient and regression analysis were used to determine the relationships between aquifer water table depth (WTD), rainfall, and shallow aquifer recharge. The Jiangjiang River Basin, a tributary of the Haihe River, was selected as the study area. The results showed that the recharge coefficient first increased, then decreased, and finally leveled off as WTD increased. When WTD was between 5 and 6 m, the recharge coefficient reached its maximum (approximately 0.3). When WTD was greater than 10 m, the recharge coefficient remained stable (around 0.12). With regard to the sources and forms of recharge, preferential flow was dominant in the areas near the extraction wells. In contrast, plug flow became dominant in the areas distant from the wells. With the reduction of rainfall duration, the proportion of preferential flow contributing to aquifer recharge increased. With the increase of rainfall amount, the duration of aquifer recharge lengthened.     

沈阳市地下水库建设的技术可行性分析

地下水在我国尤其是北方地区城乡供水中占较大比例。地下水库因具有地表水与地下水资源联合调控、多年调蓄、水资源战略储备及应急供水等功能而受到越来越广泛的关注。在分析地下水库基本结构的基础上,提出了建设地下水库的基本条件,并以沈阳市为例进行分析,给出了论证地下水库补给水源、补给区、地下水库储水空间估算及开采条件的具体分析与计算方法。最后利用建立的地下水流数值模型,模拟预测了地下水库建成后分别按常规水源与应急水源两种方式所产生的供水规模。结果表明,在研究区建设地下水库具有较高可行性。     

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.     

On the prediction of groundwater mound formation due to transient recharge from a rectangular area

Recharge to the aquifer leads to the growth of a groundwater mound. Therefore, for the proper management of an aquifer system, an accurate prediction of the spatio-temporal variation of the water table is very essential. In this paper, a problem of groundwater mound formation in response to a transient recharge from a rectangular area is investigated. An approximate analytical solution has been developed to predict the transient evolution of the water table. Application of the solution and its sensitivity to the variation of the recharge rate have been illustrated with the help of a numerical example.Notations a = Kh/e [L²/T] - A = aquifer's extent in the x-direction [L] - B = aquifer's extent in the y-direction [L] - e = effective porosity - h = variable water table height [L] - h ₀= initial water table height [L] - h = weighted mean of the depth of saturation [L] - K = hydraulic conductivity [L] - m, n = integers - P = constant rate of recharge [L/T] - P ₁+P₀= initial rate of transient recharge [L/T] - P ₁= final rate of transient recharge [L/T] - s = h ²–h ₀ ² [L²] - t = time of observation [T] - x,y = space coordinates - x ₂–x₁= length of recharge area in x-direction [L] - y ₂–y₁= width of recharge area in y-direction [L] - z = decay constant [T^-1]     

A Suitable Tool for Sustainable Groundwater Management

Artificial recharge is used to increase the availability of groundwater storage and reduce saltwater intrusion in coastal aquifers, where pumping and droughts have severely impaired groundwater quality. The implementation of optimal recharge methods requires knowledge of physical, chemical, and biological phenomena involving water and wastewater filtration in the subsoil, together with engineering aspects related to plant design and maintenance operations. This study uses a novel Decision Support System (DSS), which includes soil aquifer treatment (SAT) evaluation, to design an artificial recharge plant. The DSS helps users make strategic decisions on selecting the most appropriate recharge methods and water treatment technologies at specific sites. This will enable the recovery of safe water using managed aquifer recharge (MAR) practices, and result in reduced recharge costs. The DSS was built using an artificial intelligence technique and knowledge-based technology, related to both quantitative and qualitative aspects of water supply for artificial recharge. The DSS software was implemented using rules based on the cumulative experience of wastewater treatment plant engineers and groundwater modeling. Appropriate model flow simulations were performed in porous and fractured coastal aquifers to evaluate the suitability of this technique for enhancing the integrated water resources management approach. Results obtained from the AQUASTRESS integrated project and DRINKADRIA IPA CBC suggest the most effective strategies for wastewater treatments prior to recharge at specific sites.     

Methods for Integrating an Extensive Geodatabase with 3D Modeling and Data Management Tools for the Virttaankangas Artificial Recharge Project, Southwestern Finland

An Oracle® relational database was integrated with a data management system including custom-made user interface, surface modeling, and three-dimensional (3D) modeling tools to produce an easily updatable 3D hydrogeologic model of the Virttaankangas aquifer, southwestern Finland. The area will be used to provide the 285,000 inhabitants of the Turku region with artificially recharged groundwater. The implementation of this artificial recharge project requires capabilities to store and process a variety of data, which are updating on a daily basis. The database and the integrated modeling tools allow the user to concentrate on the interpretation of geologic factors and their interactions and to have an access to the most up-to-date 3D hydrogeologic model, while the common and laborious routine tasks have been automated. Integration of the geodatabase, 3D hydrogeologic model, groundwater flow model and possible solute transport models can be used to reach the quantitative understanding of the aquifer system. During the process, the benefits of using geologic models and other visualization tools can be applied to many sectors involved with the artificial infiltration project.     

基于EMD-LSTM耦合模型的趵突泉岩溶地下水水位预测应用

由于岩溶地下水具有强烈的非线性及非平稳波动特征,水位预测结果容易产生较大误差。针对岩溶地下水水位预测精度较差的问题,提出一种EMD-LSTM耦合模型,首先采用经验模态分解（EMD）将趵突泉岩溶地下水水位分解为5个分量（4个本征模函数项和1个残余项）,以此消除水位数据的非平稳波动性;同时构建长短期记忆（LSTM）神经网络模型,并将与地下水水位动态变化密切相关的降水量（表征含水层补给项）和月平均气温值、月最高气温值、月最低气温值、水汽压值（表征含水层排泄项）作为输入项分别对5个分量进行预测,最终将分量预测结果累加获得地下水水位预测值。结果表明：EMD能够显著消除岩溶地下水水位的非平稳波动特征;EMD-LSTM耦合模型可有效提高岩溶地下水水位的预测精度,其均方根误差相比于LSTM神经网络模型、ARIMA模型分别减小了27.86%和59.94%。总体来说,本文所提出的EMD-LSTM耦合模型具有较强的可靠性和稳定性,可为岩溶地下水水位的精确预测提供借鉴。     

Effect of management strategies on reducing negative impacts of climate change on water resources of the Isfahan–Borkhar aquifer using MODFLOW

Recently, many studies have investigated the effect of climate change on groundwater resources in semiarid and arid areas and have shown adverse effects on groundwater recharge and water level. However, only a few studies have shown suitable strategies for reducing these adverse effects. In this study, climate conditions were predicted for the future period of 2020–2044, under the emission scenarios of RCP2.6, RCP4.5, and RCP8.5, for Isfahan–Borkhar aquifer, Isfahan, Iran, using MODFLOW‐2000 (MODFLOW is United States Geological Survey product). Results showed that the average groundwater level of the aquifer would decrease to 13, 15, and 16 m in 2012 to 2044 approximately under RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively. Then, three groundwater sustainability management scenarios were defined that included 10%, 30%, and 50% reduction in groundwater extraction. These strategies simulated the reduced negative effects of climate change on the aquifer. The results showed that decreases in water withdrawal rates of 10%, 30%, and 50% under RCP8.5 scenario (critical scenario) could decrease the mean groundwater level by 14, 11, and 7 m, respectively. The main result of the study showed that 50% reduction in groundwater withdrawal may increase the groundwater levels significantly in order to restore the aquifer sustainability in the study area. In this study, with assuming that the current harvest of wells in the future period is constant, so the results of studies showed that for the aquifer's sustainability management, the water abstraction from the aquifer should reduce up to 50% of the existing wells. Changing the irrigation method from surface to subdroplet irrigation plays an important role in reducing the withdrawal from the aquifer. The results of a study in Iran have shown that the change in the irrigation method from surface to subdroplet irrigation causes a 40% reduction in water use for agriculture.