Future groundwater conditions under long-term water stresses in an arid urban area

The urban area of Greater Dhahran has an extremely arid climate where the average annual rainfail is less than 71 mm. The Umm Er Radhuma (UER) aquifer in that area is the main source of domestic and landscape irrigation demands. Groudwater use has increased drastically during the last 15 years due to extensive developments in the area. Numerical simulation techiques and hydrogeochemical investigations were carried out to assess the effects of increasing pumping rates on the piezometric surface in the UER aquifer and to predict the future levels and quality of water under different pumping scenarios. A groundwater flow model was developed and calibrated for the area. The increase in the water extraction rate between 1967 and 1990 has resulted in a decline in the piezometric surface by about 4 m in the Dhahran area. The results of simulation investigations indicated that if the present trend of the groundwater withdrawal rate continues, the water level is expected to drop by an additional 2 and by the end of the year 2000, by an additional 6 m by the end of 2010. If the present increasing rate in groundwater withdrawal is reduced by 50%, the additional drawdown will also be reduced to about 1 and 2.5 m by the end of years 2000 and 2010, respectively. The average total dissolved solids (TDS) has increased from 2750 to 3545 mg/l between 1967 and 1990 and will continue to rise to 3922 and 4361 by the end of years 2000 and 2010, respectively. These original findings are important because they postulates the negative impacts of increasing groundwater pumping from an aquifer in an arid urban area on future groundwater levels and quality. Therefore, effective groundwater management and conservation schemes should be adopted to maintain the long-term productivity and quality of aquifers in the area.     

Palaeohydrogeology and Water Quality Control of the Tertiary Aquifer,Kuwait

Abstract

The State of Kuwait is located at the northwestern corner of the Arabian Gulf and covers an area of about ≈18,000 km2. The aquifer under investigation is the Eocene Dammam limestone aquifer. This paper discusses the hydrochemistry of the aquifer through the period 1972–2002 in order to identify the chemical and genetic types of groundwater, and to reveal the prevailing geochemical processes in the aquifer. Moreover, the spatial distribution of the brackish-brine groundwater is encountered to provide an overview of the regional scale hydrochemistry and to assess the possible factors controlling the aquifer quality. Accordingly, WATEQ4F program is used to compute the saturation indices of the minerals with respect to a state water composition. The Z- MAP and the STRATWORKS programs are used to construct the structural contour map and the subsurface geophysical logs of the Dammam Formation, respectively.

The hydrochemical and geological investigations revealed that the Dammam limestone aquifer is occupied by a brackish-brine groundwater, with TDS values ranging from 2500 to 150,000 mg/l, which gradually increases towards the N—NE in the flow direction. The main recognized groundwater chemical types are: Na2SO4, CaSO4 and NaCl. Three groundwater genetic types Na-SO4, Mg-Cl, and Ca-Cl are dominant and indicate a continentalmarine stagnant environment.

Also, the study showed that the groundwater is oversaturated with respect to calcite and dolomite, and under-saturated with respect to gypsum. The calculated mean values of PCO2 range between 8.79 x 10–4 and 1.38 x 10–2 atm., which are above that of PCO2 of the earth' atmosphere. These high values of PCO2 suggest that the Dammam limestone aquifer represents a closed system with respect to CO2. The ion-exchange, reverse ion-exchange and dedolomitization are the main geochemical processes prevailing in the aquifer. Furthermore, the carbonate weathering is most likely to operate in the aquifer. Controls on the distribution of water qualities reflect the ancient marine depositional environment, water-rock interaction, aquifer flushing including ion exchange effect, and the structural feature related to the Persian Gulf synclinorium.     

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.     

人类活动对鲁北平原地下水环境影响特征研究

从近10年来对鲁北平原地下水环境问题的调查成果出发,论述了人类活动对鲁北平原地下水环境的影响特征,包括浅层地下水污染、含水层疏干等的分布、形成规律及发展趋势.鲁北平原浅层地下水主要污染物为三氮、砷、铅等重(类)金属,个别地方存在有机物污染.深层含水层疏干主要发生在长期以深层地下水作为生活和工业水源的德州,深层含水层疏干引发了地面沉降;浅层地下水疏干发生在以浅层地下水为农业供水水源的冠县和宁津县.通过对鲁北平原地下水环境问题的分布现状、产生原因及规律、发展趋势及其危害的研究,提出了相应的预防措施及可持续发展对策.     

Simulation Modeling for Efficient Groundwater Management in Balasore Coastal Basin,India

The Balasore coastal groundwater basin in Orissa, India is under a serious threat of overdraft and seawater intrusion. The overexploitation resulted in abandoning many shallow tubewells in the basin. The main intent of this study is the development of a 2-D groundwater flow and transport model of the basin using the Visual MODFLOW package for analyzing the aquifer response to various pumping strategies. The simulation model was calibrated and validated satisfactorily. Using the validated model, the groundwater response to five pumping scenarios under existing cropping conditions was simulated. The results of the sensitivity analysis indicated that the Balasore aquifer system is more susceptible to the river seepage, recharge from rainfall and interflow than the horizontal and vertical hydraulic conductivities and specific storage. Finally, based on the modeling results, salient management strategies are suggested for the long-term sustainability of vital groundwater resources of the Balasore groundwater basin. The most promising management strategy for the Balasore basin could be: a reduction in the pumpage from the second aquifer by 50% in the downstream region and an increase in the pumpage to 150% from the first and second aquifer at potential locations.     

Hydrochemical Processes and Environmental Isotopic Study of Groundwater in Kuwait

Abstract

The present paper studies the hydrochemical processes and the isotopic characteristics of the main aquifers, the Kuwait Group and Dammam aquifers in the State of Kuwait. The water chemical types are dominantly NaCl and Na₂SO₄ in the Kuwait Group aquifer and Na₂SO₄, CaSO₄, and NaCl in the Dammam Limestone aquifer. The groundwater of the Kuwait Group aquifer is supersaturated with respect to quartz and calcite, and near saturation with respect to aragonite, but under-saturated with respect to anhydrite, dolomite, gypsum, and halite. While the groundwater of the Dammam aquifer is strongly under-saturated with respect to anhydrite, halite, and gypsum and is supersaturated with respect to quartz, dolomite, aragonite, and calcite. The saturation indices of the calcite and dolomite are increased in the direction of flow from southwest toward north-northeast. Al-Rawdhatain and Umm Al-Aish groundwater samples lie near the meteoric water line. They represent the effect of recharge by rainfall during pluvial period. The brackish palaeo-groundwater of the Dammam aquifer has low values of δ¹⁸O (?4.5 per mil) and δD (?35 per mil), which reveal that these waters are related to the palaeo-water from the cool wet period in the eastern Arabia 11,000 to 60,000 years B.P. The investigated brackish groundwater samples showed that the deuterium excess values are much lower than that of the Mediterranean areas. This may suggest that the evaporation was a prevailing process before the infiltration to the aquifers.     

Modelling of the Shegaya,Sulaibiya and Umm Gudair fields in Kuwait

Numerical modelling of the two main aquifers in Kuwait—the Kuwait Group and Dammam Limestone aquifers—was carried out. Two different well designs were represented in the model: wells completed in the Dammam Limestone aquifer and dual completion wells in both aquifers. The results of the modelling suggested that (i) most of the decline in potentiometric heads will take place in the central and northern part of the study area, (ii) the direction of vertical leakage, which was upward initially, will change to a downward direction (from the Kuwait Group to Dammam Limestone) and (Hi) the flow direction may change in the eastern part of the study area from north to north‐east.     

滨海盆地变密度地下水流与溶质运移三维耦合数值模型研究

针对滨海含水层的复杂性,以北部湾经济区合浦盆地地下水资源应急潜力评价为例,通过概化出合浦盆地水文地质概念模型的基础上,采用SEAWAT模块建立了合浦盆地变密度地下水流与溶质运移三维耦合数值模型。在对模型进行识别、验证的基础上,假设2025年10月出现极端干旱,在保证不发生海水入侵的条件下,获得了度过整个枯水期各水源地地下水资源应急潜力。结果表明:合浦盆地地下水资源应急潜力为83.13万m~3/d,集中开采区中心地下水水头下降3～8 m, 2 a后水位基本恢复;集中开采区降落漏斗远离海岸线,不受到海水入侵的影响。该方法将滨海水源地地下水应急供水预测和盆地的水文地质结构及当地发展规划紧密结合起来,为合浦盆地地下水资源的合理开发利用和应急能力建设提供了可靠依据。     

Predictive Simulation of Flow and Solute Transport for Managing the Salalah Coastal Aquifer, Oman

A three-dimensional numerical model for flow and solute transport was used for the management of the Salalah aquifer. The model calibration procedures consisted of calibrating the aquifer system hydraulic parameters by history matching under steady and transient conditions. The history of input and output of the aquifer were reconstructed in a transient calibration from 1993 to 2005. Predictive simulation of the aquifer was carried out under transient conditions to predict the future demand of groundwater supply for the next 15 years. A baseline scenario was worked out to obtain the piezometric surface and salinity distribution for the “business as usual” conditions of the aquifer. The “business as usual” scenario was predicted and simulated for the period 2006 until 2020. The effectiveness of seven management options was proposed and assessed for comparison with the “business as usual” conditions. The established simulation model was used to predict the distribution of the piezometric surface, salinity distribution, and mass balance under the proposed scenarios for the prediction period 2006–2020. The scenarios were: (1) relocate Garziz and MAF farms far from the freshwater zone, (2) suspend the abstraction of grass production for 4 months a year, (3) changes in agricultural and irrigation system patterns, (4) establish a desalination plant, (5) combined scenario (1 + 4), (6) combined scenario (1 + 3), and (7) combining all scenarios (1 + 2 + 3 + 4). The result of the simulation shows that the best effective option in terms of aquifer groundwater levels is the fifth proposed scenario and the sixth proposed scenario is the best effective option in terms of aquifer groundwater salinity situation during the next 15 years. This project suggested the application of scenario 6 as it is environmentally sound in terms of sustainable management. A prediction has been made which shows that further actions have to be taken within the next two decades to ensure continuity of the municipal water supply. The management scenarios are examined in the case of the Salalah coastal aquifer using groundwater simulation, which can also be applied to other regions with similar conditions. The established model is considered a reasonable representation of the physical conditions of the Salalah plain aquifer, and can be used as a tool by the water and environmental authorities in the management of the groundwater in the region.     

悬挂式止水帷幕圆形基坑承压含水层地下水非稳定流计算

针对悬挂式止水帷幕基坑中复杂的地下水流动,建立了考虑止水帷幕的圆形基坑承压含水层地下水非稳定流动计算模型。通过对地下水流动计算模型的Laplace变换和有限Fourier余弦变换,推导了Laplace空间的水头降深解,采用Stehfest数值逆变换提出了悬挂式止水帷幕圆形基坑承压含水层地下水非稳定流水头降深半解析解。在验证计算方法正确性和数值逆变换计算准确性的基础上,利用工程实例验证了计算方法的工程适用性。分析了悬挂式止水帷幕插入深度对圆形基坑地下水流动的影响规律,阐明了止水帷幕对基坑内外地下水控制的积极作用,为合理开展悬挂式止水帷幕圆形基坑承压含水层的减压降水设计提供了计算方法。     

Brackish groundwater resources in Bahrain: Current exploitation,numerical evaluation and prospect for utilization

In Bahrain, where water resources available for direct use are finite and the best of its quality has a salinity of over 2.5 g L^–1, utilization of brackish groundwater is an essential part in the management of the country's water resources. Bahrain's brackish water occurs in the Rus-Umm Er Radhuma formations in the form of a lens of a finite lateral extent, with a salinity ranges between 8 and 15 g L^–1. Planning for utilization of brackish groundwater for desalination purposes in Bahrain was based on simulation modeling of the aquifer system using a mixing cell model developed originally in 1983. The model was used to predict the aquifer response to pumping from the proposed wellfield in terms of changes of TDS over a period of 20 years. Construction and operation of the wellfield in 1984 was based on the predicted salinity changes. Over the past 9 uears of wellfield operation (1984–1993), and through continuous monitoring of the aquifer response to pumping, the collected data is used to post-audit the original model by history matching. The calibration process adopted has resulted in a statisfactory agreement between the model output and the observed data. The model is then used to predict the wellfield salinity changes and the aquifer potentiometric levels. The expected life span for the brackish groundwater utilization by the wellfield is redefined through constrained utilization that takes into account salinity deterioration coupled with the effect of head decline on hydraulic interaction between the brackish water and the upper fresh water aquifer. The results suggest that the operation of the wellfield should cease by the year 2007. Construction of a new model that enables testing and evaluating different development scenarios is recommended to aid future management decisions regarding the utilization of brackish groundwater.     

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.     

宁南地区地下水系统划分方法研究

地下水系统的划分是正确评价宁南地区地下水资源的基础,以拥有独立的含水层系统和完整的水循环流动系统为原则,以构造控水理论为依据,将宁南地区地下水系统划分为9个一级地下水系统,19个二级地下水系统。地下水系统的划分有利于对当地地下水资源做出准确评价、开发、规划和管理。     

Assessment of groundwater resources in Kuwait using a finite difference model

Usable groundwater resources have strategic significance, given the arid climate of Kuwait. Assessment of groundwater resources through modelling is considered of paramount importance for sustained long‐term development of this resource. A conceptual model of the regional hydrogeology of the area has been developed based on the available data. Three aquifers were recognized within the Dammam Formation‐Kuwait Group sequence. VTDN software was used for numerical simulation of the groundwater flow in this aquifer system under steady‐state conditions. Calibration runs made to date suggest that the model is sensitive to the vertical coefficient of permeability of the aquitards and the horizontal transmissi‐vities of the aquifers. The water balance achieved shows that the contribution from the natural recharge from precipitation is insignificant.     

Stochastic and Robust Multi-Objective Optimal Management of Pumping from Coastal Aquifers Under Parameter Uncertainty

Combined simulation-optimization approaches have been used as tools to derive optimal groundwater management strategies to maintain or improve water quality in contaminated or other aquifers. Surrogate models based on neural networks, regression models, support vector machies etc., are used as substitutes for the numerical simulation model in order to reduce the computational burden on the simulation-optimization approach. However, the groundwater flow and transport system itself being characterized by uncertain parameters, using a deterministic surrogate model to substitute it is a gross and unrealistic approximation of the system. Till date, few studies have considered stochastic surrogate modeling to develop groundwater management methodologies. In this study, we utilize genetic programming (GP) based ensemble surrogate models to characterize coastal aquifer water quality responses to pumping, under parameter uncertainty. These surrogates are then coupled with multiple realization optimization for the stochastic and robust optimization of groundwater management in coastal aquifers. The key novelty in the proposed approach is the capability to capture the uncertainty in the physical system, to a certain extent, in the ensemble of surrogate models and using it to constrain the optimization search to derive robust optimal solutions. Uncertainties in hydraulic conductivity and the annual aquifer recharge are incorporated in this study. The results obtained indicate that the methodology is capable of developing reliable and robust strategies for groundwater management.     

Groundwater Exploration and Assessment in Rural Communities of Yobe State, Northern Nigeria

The provision of adequate water supply and sanitation to the rapidly growing urban populations is increasingly becoming a problem for governments throughout the world. The continuing expansion of the numbers of people in cities who need water and sanitation services form a continuous pressure to either invest in additional production capacity or to stretch the available supplies to serve more people. Due to rapid increase in population growth in the Yobe State north of Nigeria, there is a shortage in the water supply to Damaturu city the capital of the state and surrounding villages. At the present the total water supply is about 10,000 m³/day abstracted form the shallow alluvial groundwater aquifer using 29 production wells. Due to the expected increase in water demand and the limited potentiality of shallow aquifer system, other deep aquifers were explored and investigated to evaluate their potentiality for future water demand. Vertical Electrical Sounding Method was used for the geophysical survey of the study area. Groundwater flow model was developed and calibrated against the historical information. Three wellfields were designed to provide Damaturu city and surrounding villages with the required water. The calibrated model has been used to evaluate the aquifer potentiality and the effect of future withdrawals on the deep aquifer system. It was found that the aquifer system within the study area consists of two main layers. The upper layer is the Chad formation comprises an alluvial sand and gravel with intercalation of thin sility clay layers. The second layer is Keri-Keri formation consists of sandstone formation which is not explored before. During this study the Kerri-Kerri aquifer system was investigated as an alternative source for groundwater for future demand. The study presents an integrated groundwater resources management strategy for present and future water supply for rural communities.     

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.     

Search beam method

An interactive multi‐objective decision‐making (MODM) model based on the Search Beam Method (SBM) and a finite‐difference groundwater flow model (GWM), is developed for analysing groundwater resources development and management problems. The SBM utilizes one‐dimensional search in the objective space to (systematically) identify the non‐dominated solutions. The steady‐state GWM determines the aquifer response due to well withdrawals. Three competing objectives of maximizing total yield, minimizing maximum compression and minimizing total pumping cost are considered. Applicability of the MODM model is demonstrated on a simplified confined aquifer system resembling one of the water‐bearing layers underlying Bangkok.     

Groundwater use and policy options for sustainable management in Southern Iraq

An important challenge facing the design of sustainable aquifer management plans is weak primary data on aquifer recharge and use patterns. Weak data limit the ability of policy makers to design efficient aquifer protection plans. The objectives of this article are (1) to estimate groundwater use patterns for an important food-producing region of southern Iraq, the Bahr Al-Najaf Basin; (2) to compare groundwater use patterns with the renewable groundwater supply; and (3) to describe a sustainable groundwater policy alternative to current use patterns. For this study, original data on groundwater pumping were secured for 2006–2011. The data show a pattern of unsustainable groundwater withdrawals. A policy intervention is described in which pumping permits could be assigned to groundwater users to promote sustainable use. Allowing or encouraging the permits to be transferable through trading to higher-valued uses could reduce the economic costs of protecting the aquifer while promoting its sustainable use.     

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.