地下水化学动力学法在大庆前进水源地求参中的应用

大庆前进水源地自20世纪80年代运行以来,随着开采活动的加剧,地下水系统状态已发生改变,水资源重新评价势在必行。依据已有水文地质和水质分析资料,运用地下水化学动力学理论和方法,通过水化学指标（组分活度α、矿物饱和指数β）的计算分析,结合有限的抽水试验资料,分区计算出渗透系数K、导水系数T、地下水实际流速U、渗透速度V和地下水年龄t等5项水文地质参数,定量的认识水文地质条件,认证了水源地泰康组承压含水层具有渗透性强、导水性强、地下水循环交替快、可更新能力强等特点。不仅为地下水资源评价提供了参数,也为水源地持续合理地开发管理提供了定量依据。     

云应盆地东北部含水层结构特征及地下水转化模式

云应盆地东北部属鄂北贫水地区,赋存于古近系—第四系含水层中的地下水是当地生产、生活用水的主要来源,亟需查明含水层的结构、含水层间地下水的转化关系等基本条件,为研究区内合理开发利用地下水提供依据。本研究通过野外水文地质调查、水文地质钻探工作,将研究区划分为单层含水层与双层含水层结构两个亚区（6个小区）。并通过地下水水位动态长期监测,获取了区内不同含水层的水位动态变化特征,分析各含水层之间的水力联系,建立了区域地下水转化的概念模式,即:研究区地下水以接受山前降雨入渗及风化裂隙水侧向径流补给为主,主要以水平径流的形式经古近系孔隙-裂隙含水层及第四系孔隙承压含水层往澴水方向运移,而后进入第四系孔隙潜水含水层。地下水和地表水在不同季节补排模式不同,雨季地表水（澴水）补给地下水,旱季地下水向地表水（澴水）排泄。古近系孔隙-裂隙水与上覆第四系孔隙水联系密切互为补给,共同构成具有统一水力联系的垂向多层结构的含水系统。独特的含水层结构决定了区内地下水接受降水补给的条件较差,地下水可开采资源量总体较贫乏,建议重点利用区域地表水资源,适度开发地下水资源,推进农业节水灌溉工程,实现水资源可持续利用。     

A multi-method approach for groundwater resource assessment in coastal carbonate (karst) aquifers: the case study of Sierra Almijara (southern Spain)

Understanding the transference of water resources within hydrogeological systems, particularly in coastal aquifers, in which groundwater discharge may occur through multiple pathways (through springs, into rivers and streams, towards the sea, etc.), is crucial for sustainable groundwater use. This research aims to demonstrate the usefulness of the application of conventional recharge assessment methods coupled to isotopic techniques for accurately quantifying the hydrogeological balance and submarine groundwater discharge (SGD) from coastal carbonate aquifers. Sierra Almijara (Southern Spain), a carbonate aquifer formed of Triassic marbles, is considered as representative of Mediterranean coastal karst formations. The use of a multi-method approach has permitted the computation of a wide range of groundwater infiltration rates (17–60%) by means of direct application of hydrometeorological methods (Thornthwaite and Kessler) and spatially distributed information (modified APLIS method). A spatially weighted recharge rate of 42% results from the most coherent information on physiographic and hydrogeological characteristics of the studied system. Natural aquifer discharge and groundwater abstraction have been volumetrically quantified, based on flow and water-level data, while the relevance of SGD was estimated from the spatial analysis of salinity, ²²²Rn and the short-lived radium isotope ²²⁴Ra in coastal seawater. The total mean aquifer discharge (44.9–45.9 hm³ year^?1) is in agreement with the average recharged groundwater (44.7 hm³ year^?1), given that the system is volumetrically equilibrated during the study period. Besides the groundwater resources assessment, the methodological aspects of this research may be interesting for groundwater management and protection strategies in coastal areas, particularly karst environments.     

Hydrogeology of karst aquifer systems in SW Turkey and an assessment of water quality and contamination problems

The aim of this research is to determine the relationship between groundwater flow and water quality of different ground and surface water basins in the southwest Turkey. In addition, groundwater vulnerability is assessed taking into consideration groundwater flow and quality. The autochthonous Beydaglari limestone is the major karstic aquifer in the region. According to the groundwater level map of alluvium aquifers in the basins, groundwater discharge toward the carbonate aquifer is direct and indirect. The hydrogeological connection between ground and surface water basins occurs via the karstic aquifer located at the bottom of the alluvium bottom. In Egirdir lake, water also discharges in the karstic aquifer via karstic sinkholes at the western border of the lake. In the research area, general groundwater discharge is toward the Mediterranean Sea by means of autochthonous carbonate system, according to hydrogeological investigations, research of lineament and hydraulic conductivities. This result is supported by the locations of lineaments and shore springs discharging from the limestone. In addition, spreading of contaminants via karstic aquifer to great distance has been clearly identified.     

Role of high-elevation groundwater flows in the hydrogeology of the Cimino volcano (central Italy) and possibilities to capture drinking water in a geogenically contaminated environment

Origin, yield and quality of the groundwater flows at high elevation in the Cimino volcano (central Italy) were examined. In this area, groundwater is geogenically contaminated by arsenic and fluoride, yet supplies drinking water for approximately 170,000 inhabitants. The origin of the high-elevation groundwater flows is strictly related to vertical and horizontal variability of the rock types (lava flows, lava domes and ignimbrite) in an area of limited size. In some cases, groundwater circuits are related to perched aquifers above noncontinuous aquitards; in other cases, they are due to flows in the highly fractured dome carapace, limited at the bottom by a low-permeability dome core. The high-elevation groundwater outflow represents about 30% of the total recharge of Cimino’s hydrogeological system, which has been estimated at 9.8 L/s/km². Bicarbonate alkaline-earth, cold, neutral waters with low salinity, and notably with low arsenic and fluoride content, distinguish the high-elevation groundwaters from those of the basal aquifer. Given the quantity and quality of these resources, approaches in the capture and management of groundwater in this hydrogeological environment should be reconsidered. Appropriate tapping methods such as horizontal drains, could more efficiently capture the high-elevation groundwater resources, as opposed to the waters currently pumped from the basal aquifer which often require dearsenification treatments.

     

Effects of solution mining on groundwater quality in the Kazan trona field,Ankara-Turkey: model predictions

Three aquifer systems as deep, middle, and shallow were identified in the Kazan trona ore deposit area. The flow conditions and the interaction between various layers were conceptualized into a site hydrogeological model. Each aquifer system was hydraulically and chemically characterized and represented in a numerical groundwater model. The resulting model has been calibrated under steady-state and transient conditions using available data. The flow model was used in conjunction with a three-dimensional solute transport model to assess the impacts of the pilot well solution mining of the trona deposit on groundwater resources during operation and post-operation periods. The results of operation period indicate that, even under the worse conditions (50 times increase in vertical hydraulic conductivity due to subsidence), ion contribution from the mine area with 118,000 mg/l maximum concentration would be about 58 mg/l into the deep aquifer system. This contribution is about 1.45% of the existing concentration (4,000 mg/l) in the deep aquifer. After 1,000 years of post-operation period, ion contribution from the mine area with maximum 119,000 mg/l concentration would be about 205 mg/l into the deep aquifer under extremely worse conditions. This contribution is about 5–20% of present concentrations in the deep aquifer. Retardation factors, which were not considered during model simulations would decrease the predicted concentrations. It is concluded that pilot well solution mining of the trona deposit would not have significant impact on the quality of groundwater resources in the overlying aquifers.     

Hydrostratigraphic framework and hydrogeological behaviour of the Mancha Oriental System (SE Spain)

The Mancha Oriental System (MOS) has a surface area of 7,260 km², making it one of the largest carbonate aquifer systems in Spain. The system sustains about 1,000 km² of irrigated crops and supplies groundwater to 275,000 inhabitants. The economic transformation brought about by the development of extensive irrigated cropland has led to a water-balance disequilibrium of about 75 million m³/year. This input–output deficit has negative consequences in the quantity and quality of the available resources, in the river–aquifer relationship, and in the associated ecosystems as well. To understand the hydrogeological behaviour of the system, it is necessary to design a conceptual model. Further, the conceptualisation of a groundwater flow system is a requirement of the European Water Framework Directive for the characterisation of groundwater bodies. The robustness of the conceptual model depends heavily on the user capability of representing the real system. In this work, a multidisciplinary approach has been used to represent the three-dimensional geological framework and the groundwater flow conceptualisation of the MOS. Data management and three-dimensional visualisation have been carried out by means of geographical information system (GIS) tools and software for contouring and three-dimensional surface mapping.     

Assessing Groundwater Resource Vulnerability by Coupling GIS-Based DRASTIC and Solute Transport Model in Ajmer District,Rajasthan

Groundwater aquifer vulnerability has been assessed by incorporating the major geological and hydrogeological factors that affect and control the groundwater contamination using GIS-based DRASTIC model along with solute transport modeling. This work demonstrates the potential of GIS to derive a vulnerability map by overlying various spatially referenced digital data layers (i.e., depth to water, net recharge, aquifer media, soil media, topography, the impact of vadose zone and hydraulic conductivity) that portrays cumulative aquifer sensitivity ratings in Kishangarh, Rajasthan. It provides a relative indication of groundwater aquifer vulnerability to contamination. The soil moisture flow and solute transport regimes of the vadose zone associated with specific hydrogeological conditions play a crucial role in pollution risk assessment of the underlying groundwater resources. An effort has been made to map the vulnerability of shallow groundwater to surface pollutants of thestudy area, using soil moisture flow and contaminant transport modeling. The classical advection-dispersion equation coupled with Richard’s equation is numerically simulated at different point locations for assessing the intrinsic vulnerability of the valley. The role of soil type, slope, and the land-use cover is considered for estimating the transient flux at the top boundary from daily precipitation and evapotranspiration data of the study area. The time required by the solute peak to travel from the surface to the groundwater table at the bottom of the soil profile is considered as an indicator of avulnerability index. Results show a high vulnerability in the southern region, whereas low vulnerability is observed in the northeast and northern parts. The results have recognized four aquifer vulnerability zones based on DRASTIC vulnerability index (DVI), which ranged from 45 to 178. It has been deduced that approximately 18, 25, 34, and 23% of the area lies in negligible, low, medium and high vulnerability zones, respectively. The study may assist in decision making related to theplanning of industrial locations and the sustainable water resources development of the selected semi-arid area.     

山西太原晋祠—兰村泉水复流的岩溶水文地质条件新认识

晋祠泉和兰村泉是山西著名的岩溶大泉,受自然条件变化和人类活动的影响,两个泉于20世纪末相继断流。针对山西省政府提出的要使晋祠、兰村泉水复流的生态修复目标任务,文章在泉域水文地质调查基础上,就泉水复流密切相关的四个关键性岩溶水文地质条件问题开展研究并提出了新认识。核实了目前划定的晋祠—兰村泉域边界,依据最新资料对现行的晋祠、兰村泉域边界提出了7处修正,修改后晋祠泉域面积由2 030 km2变为2 713 km2,兰村泉域面积由2 500 km2变为2 614 km2。汾河二库在蓄水后库区的主体部分划归到晋祠泉域而非兰村泉域,其渗漏补给是造成近年来晋祠泉域区域岩溶地下水位大幅回升的主要原因。确定了晋祠泉域内盘道—马家山断裂带是一个岩溶水强富水带,也是岩溶地下水从北部中、上寒武统含水岩组向南部中奥陶统含水岩组的转换带。圈定了晋祠泉域:玉门河南峪村—杜儿平煤矿东侧—官地矿与白家庄矿交界处—龙山—明仙村东—晋祠泉的岩溶地下水强径流带。这些认识是开展晋祠—兰村泉域岩溶地下水资源评价、地下水开发管理和保护的基础,更是制定晋祠、兰村泉水复流方案的重要依据。     

Assessment of aquifer vulnerability based on GIS and DRASTIC methods: a case study of the Senirkent-Uluborlu Basin (Isparta, Turkey)

Aquifer vulnerability has been assessed in the Senirkent-Uluborlu Basin within the Egirdir Lake catchment (Turkey) using the DRASTIC method, based on a geographic information system (GIS). There is widespread agriculture in the basin, and fertilizer (nitrate) and pesticide applications have caused groundwater contamination as a result of leaching. According to hydrogeological data from the study area, surface water and groundwater flow are towards Egirdir Lake. Hence, aquifer vulnerability in the basin should be determined by water quality in Egirdir Lake. DRASTIC layers were prepared using data such as rainfall, groundwater level, aquifer type, and hydraulic conductivity. These data were obtained from hydrogeological investigations and literature. A regional-scale aquifer-vulnerability map of the basin was prepared using overlay analysis with the aid of GIS. A DRASTIC vulnerability map, verified by nitrate in groundwater data, shows that the defined areas are compatible with land-use data. It is concluded that 20.8% of the basin area is highly vulnerable and urgent pollution-preventions measures should be taken for every kind of relevant activity within the whole basin.     

GIS支持下的新疆平原区地下水资源评价模型

在阐述地下水资源系统特征的基础上,采用水均衡的基本原理,在MAPGIS、RS、数据库和VBA面向对象开发技术支持下,构建地下水资源评价模型,评价模型主要应用了遥感信息、水文地质调查、水位水质观测及其他试验资料多源信息,综合考虑了影响地下水系统的多种因素,如含水层特征、水质、植被覆盖情况以及地下水开发利用状况.该评价方法同传统方法相比,具有速度快、精度高的优点.另外,基于GIS的评价模型更大的优势是数据更新时,便于模型重新评价,最终为水资源统一规划提供可靠的决策依据.     

Hydrological and hydrogeological characteristics of Wadi el Mujib catchment area,Jordan

Hydrological and hydrogeological data in the area have been verified to evaluate the availability and the potentiality of the water resources for the proposed damsites in the Wadi el Mujib catchment area, which is considered a semiarid to arid region. The quantity of the surface waters is very small compared with the surface area of the basin, however, due to the shortage of precipitation in the country and the necessity to attain socioeconomic objectives, the investigation of these waters has become more vital. The most reliable exploitation can be essentially achieved by constructing small storage dams on the suitable sites in order to benefit from the flood waters coming from the main wadis. For the above purpose, the hydrogeological and hydrological study of Wadi el Mujib catchment area was carried out, where the Wadi Mujib dam site will be constructed. The hydrogeological investigation of the groundwater was performed by constructing a groundwater contour map of the Amman-Wadi Es Sir aquifer (B2/A7) so as to verify the groundwater flow system and to determine the potentiality of the aquifer from the hydraulic parameters obtained from the pumping test analysis. The hydrological feasibility study of the dam was carried out by evaluating the water balance for a long-term period (1970 to 1990) in order to obtain reliable data that can be used to estimate the recharge to B2/A7 aquifer. In addition, a frequency analysis was performed to estimate the flood design of the reservoir area as well as the spillway at the proposed dam site.     

The Basin of Mexico aquifer system: regional groundwater level dynamics and database development

The aquifer system of the Basin of Mexico is the main source of water supply to the Mexico City Metropolitan Zone. Management of the Basin’s water resources requires improved understanding of regional groundwater flow patterns, for which large amounts of data are required. The current study analyses the regional dynamics of the potentiometric groundwater level using a new database called the Basin of Mexico Hydrogeological Database (BMHDB). To foster the development of a regional view of the aquifer system, data on climatological, borehole and runoff variables are part of the BMHDB. The structure and development of the BMHDB are briefly explained and then the database is used to analyze the consequences of groundwater extraction on the aquifer’s confinement conditions using lithology data. The regional analysis shows that the largest drawdown rates are located north of Mexico City, in Ecatepec (a region that has not yet received attention in hydrogeological studies), due to wells that were drilled as a temporary solution to Mexico City’s water-supply problem. It is evident that the aquifer has changed from a confined to an unconfined condition in some areas, a factor that is responsible for the large subsidence rates (40 cm/year) in some regions.     

Hydrogeological framework and water balance studies in parts of Krishni–Yamuna interstream area, Western Uttar Pradesh, India

The Krishni–Yamuna interstream area is a micro-watershed in the Central Ganga Plain and a highly fertile track of Western Uttar Pradesh. The Sugarcane and wheat are the major crops of the area. Aquifers of Quaternary age form the major source of Irrigation and municipal water supplies. A detailed hydrogeological investigation was carried out in the study area with an objective to assess aquifer framework, groundwater quality and its resource potential. The hydrogeological cross section reveals occurrence of alternate layers of clay and sand. Aquifer broadly behaves as a single bodied aquifer down to the depth of 100 m bgl (metre below ground level) as the clay layers laterally pinch out. The depth to water in the area varies between 5 and 16.5 m bgl. The general groundwater flow direction is from NE to SW with few local variations. An attempt has been made to evaluate groundwater resources of the area. The water budget method focuses on the various components contributing to groundwater flow and groundwater storage changes. Changes in ground water storage can be attributed to rainfall recharge, irrigation return flow and ground water inflow to the basin minus baseflow (ground water discharge to streams or springs), evapotranspiration from ground water, pumping and ground water outflow from the basin. The recharge is obtained in the study area using Water table fluctuation and Tritium methods. The results of water balance study show that the total recharge in to the interstream region is of the order of 185.25 million m³ and discharge from the study area is of the order of 203.24 million m³, leaving a deficit balance of −17.99 million m³. Therefore, the present status of groundwater development in the present study area has acquired the declining trend. Thus, the hydrogeological analysis and water balance studies shows that the groundwater development has attained a critical state in the region.     

Evaluation of the water resources potential at Dahaban region, western Saudi Arabia

Shallow renewable groundwater sources have been used to satisfy the domestic needs and the irrigation in many parts of Saudi Arabia. Increased demand for water resulting from accelerated development activities has placed excess stress on the renewable sources especially in coastal aquifers of the western region of Saudi Arabia. It is expected that the current and future development activities will increase the rate of groundwater mining of the coastal aquifer near the major city Jeddah and surrounding communities unless management measures are implemented. The current groundwater development of Dahaban coastal aquifer located at alluvial fan at the confluence of three major Wadis is depleting the shallow renewable groundwater sources and causes deterioration of its quality. Numerical models are known tools to evaluate groundwater management scenarios under a variety of development options under different hydrogeological regimes. In this study, two models are applied—the MODFLOW for evaluating the hydrodynamic behaviors of the aquifer and MT3D salinity distribution to the costal aquifer near Dahaban town. The models’ simulation evaluates two development scenarios—the impact of excessive abstraction and the water salinity variation keeping abstraction at its current or increases in levels with or without groundwater recharge taking place. The simulation evaluated two scenarios covering a 25-year period—keeping the current abstraction at its current and the other scenario is increasing the well abstraction by 50% for dry condition (no recharge) and wet condition (with recharge). The analysis reveals that, under the first scenario, the continuation of the current pumping rates will result in depletion of the aquifer resulting in drying of many wells and quality deterioration at the level of 2,500 ppm. The results are associated with the corresponding salinity distribution in the region. Simulation of salinity in the region is a density-independent problem as salt concentration does not exceed 2,000 ppm, which is little value compared with sea salinity that amounts to 40,000 ppm. It is not recommended to increase the pumping rate than the current values. However, for the purpose of increasing water resources in the region, it is recommended to install new wells in virgin zones west of Dahaban main road. Maps of high/low potential groundwater and maps of salinity zones (more or less than 1,000 ppm) are provided and could be used to identify zones of high groundwater potential for the four studied scenarios. The implemented numerical simulation of Dahaban aquifer was undertaken to assess the water resources potential in order to reduce the depletion of sources in the future.     

Hydrogeological investigation of groundwater artificial recharge by treated wastewater in semi-arid regions: Korba aquifer (Cap-Bon Tunisia)

Korba aquifer is one of the most typical examples of overexploited coastal aquifer in the Mediterranean countries. In fact, from 1985, a considerable piezometric level drop, water salinization, and seawater intrusion were registered in the aquifer. In December 2008, Tunisian authorities initiated a general plan to groundwater management in order to augment groundwater resources, restore the piezometric levels, and improve water quality. The plan consists of artificial recharge of groundwater used treated wastewater through three infiltration basins. During the first 4 years (from December 2008 to December 2012), 1.41 Mm³ of treated wastewater was injected to the Korba aquifer. This study presents a hydrogeological assessment of groundwater evolution during the recharge processes. In this study, 32 piezometric and chemical surveys of 70 piezometers and observed wells are used to present hydrogeological investigation and water quality evolution of wastewater reuse through artificial recharge in Korba coastal aquifer. The piezometric evolution maps are used to specify the positive effect in groundwater level that exceeding 1.5 m in some regions. The interpretation of salinity evolution maps are used to indicate the improving of groundwater quality.     

The geochemical and isotopic composition of aquifer systems in the deltaic region of the Po River plain (northern Italy)

The chemical and hydrodynamic characteristics of groundwater in deltaic regions are strongly influenced by the complex stratigraphy of these areas, caused by the continuously varying depositional environments associated with their recent hydrographic evolution. As a case study, the eastern sector of the Po River plain, northern Italy, has been investigated to understand the quality of the available groundwater resources. Based on the analysis of hydrochemical and isotopic data, the recharge characteristics, the groundwater residence time and the aquifer vulnerability are defined. The results show significant qualitative degradation of the unconfined aquifer due to the shallow depth to water, while in the underlying confined aquifer, a hydrochemical facies of Ca–HCO₃ type prevails. The spatial variation and relationship between oxygen-18 and deuterium determine: firstly, hydraulic separation of the two hydrogeological units; secondly, direct infiltration of local precipitation to the unconfined aquifer; thirdly, the occurrence of waters originating in the Alps and locally from the Apennines, pervading the confined aquifer. The tritium results suggest local mixing between the superficial waters and the confined aquifer, occurring along the palaeo-river channels. This increases the pollution vulnerability of the confined hydrogeological unit within the plain, which is the only natural groundwater resource exploited for water supply.     

Characterization of the groundwater flow system in the hillside and coastal aquifers of the Mersin-Tarsus region (Turkey)

In the region between Mersin and Tarsus cities, located along the Mediterranean Sea coast in southern Turkey, the demand for groundwater has increased dramatically as the available surface water supplies have already been developed. Fundamental information is required to characterize the existing groundwater system in this area in order to establish a sustainable groundwater-use policy. For this purpose, hydrochemical and environmental isotopic data were collected and integrated with available geological and hydrogeological information to develop a conceptual model of the system. Results, backed up mainly by depleted stable isotope composition and infinitesimal tritium content, suggest that most of the groundwater along the coastal zone is supplied by the neighboring mountain belt while local precipitation has also contributes to aquifer recharge. The validation of the conceptual perspective by a steady-state numerical groundwater flow model reveals that about 90% of the recharge to the aquifer system is supplied by the deep flow of karstic groundwater fed from the Taurus Mountains. Monitoring of changes in the recharge regime of the mountain sector seems to be critical in establishing future groundwater use policies.     

Hydrogeological characterization of a carbonate aquifer using geophysical and geochemical approach: case of the Krachoua Formation in Tataouine area,Southern Tunisia

An integrated hydrogeological investigation involving geological surface data, well data (lithostratigraphical and piezometric data) and the vertical electrical sounding (VES) method was carried out in Tataouine area, Southern Tunisia to characterize the hydrogeology and the geochemistry of the Krachoua Formation aquifer. The electrical data were used to differentiate lithostratigraphic units and characterize their hydrogeological potentialities. Major elements contents within groundwater samples were assessed and some plots and diagrams have been established in order to investigate the hydrochemical properties of this aquifer and the origin of its mineralization. The Krachoua aquifer exhibits a general drawdown of the piezometric level from 2004 to 2015 reflecting a dramatic decrease in groundwater resources due to increased groundwater abstraction during the last decades. Flow directions shows that the recharge of this aquifer considered as a free aquifer is directly ensured by rainfalls over the outcropping fractured limestones. The geometry of the Krachoua Formation aquifer is tectonically controlled and structured in horst and graben features that impacted greatly the hydrogeology and the hydrodynamics of the area. Subsequent thickness and facies variations within this aquifer influenced the reservoir quality and the groundwater flows. The increased values of salinity to the northwest of the study area seems to be mainly related to the dissolution of the Upper Liassic gypsum of Mestaoua Formation which outcrops widely and can be dissolute easily by meteoric water and contaminate the Krachoua aquifer. This fact is also supported by the sulfated and calci-magnesian chloride facies of this aquifer related to the dissolution of evaporitic rocks (gypsum, anhydrite, and halite). However low salinity values are recorded within the zone where these evaporitic rocks are relatively deep.     

Groundwater hydrochemistry and origin in the south-eastern part of Wadi El Natrun,Egypt

The demand for water is rapidly increasing in Egypt, because of high population and agriculture production growth rate, which makes research of water resources necessary. The regional multi-aquifer system of the Miocene–Pleistocene age is discharged in Wadi El Natrun area. Intensive aquifer overexploitation and agricultural development in the area are related to groundwater quality deterioration. Hydrochemical and hydrogeological data was evaluated to determine the groundwater origin and quality in the south-eastern part of wadi, which appears to be more significant for water supply owing to lower groundwater salinity. The dominance of the high mineralised Cl groundwater type was found; however, also less mineralised SO₄ and HCO₃ types were identified there. Based on the ion relations, halite and gypsum dissolution and ion exchange are the most important hydrochemical processes forming the groundwater chemical composition. The Cl dominated groundwater matches the discharge part of the regional hydrogeological system. Contrary, the presence of HCO₃ and SO₄ hydrochemical types corresponds to the infiltration and transferring parts of the hydrogeological system indicating the presence of zones conducting low mineralised groundwater. The discharge area of the over-pumped aquifer in Wadi El-Natrun lies 23 m beneath the sea level with the shoreline being at the distance of 100 km, thus there is a real risk of seawater intrusion. Using the hydrochemical facies evolution diagram, four samples in the centre of the discharge area indicate advanced seawater intrusion. The zones of the highest demand for groundwater quality protection were indicated based on a spatial pattern of hydrogeochemical composition.