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1.
ABSTRACT

Groundwater is used by 3?million inhabitants in the coastal urban city of Douala, Cameroon, but comprehensive data are too sparse for it to be managed in a sustainable manner. Hence this study aimed to (1) assess the potability of the groundwater; (2) evaluate the spatial variation of groundwater composition; and (3) assess the interaction and recharge mechanisms of different water bodies. Hydrogeochemical tools and methods revealed the following results in the Wouri and Nkappa formations of the Douala basin, which is beneath Douala city: 30% of water samples from hand-dug wells in the shallow Pleistocene alluvium aquifer were saline and highly mineralized. However, water from boreholes in the deeper (49–92 m depth) Palaeocene aquifer was saline-free, less mineralized and potable. Water in the shallow aquifer (0.5–22 m depth) was of Na+-K+-Cl?-NO3? type and not potable due to point source pollution, whereas Ca+-HCO3? unpolluted water dominates in the deeper aquifer. Water in the deep and shallow aquifers indicates the results of preferential flow pass and evaporative recharge, respectively. Possible hydrogeochemical processes include point source pollution, reverse ion exchange, remote recharge areas and mixing of waters with different chemical signatures.
EDITOR D. Koutsoyiannis ASSOCIATE EDITOR M.D. Fidelibus  相似文献   

2.
In order to maintain the scenic and eco-environmental values of a lake, we need to characterize its water interactions. Shahu Lake was used as a case study to show the interactions among replenishment water, lake water and groundwater in an arid region. Shahu Lake is located in the Ningxia Hui Autonomous Region of northwest China and has an area of 13.96 km2 and an average depth of 2.2 m. The groundwater modelling software MODFLOW was used. The analysis results show that hydraulic connectivity among replenishment water, lake water and groundwater is the crucial driving factor that affects the water level in Shahu Lake. The lake water level is highly sensitive to the volume of replenishment water. The groundwater is of great importance in balancing the water level in the lake and preventing it from drying up. It was determined that 13.8 × 106 m3/yr is the optimal volume of replenishment water for Shahu Lake in order to maintain the lake level at its normal state and also to make the best use of available water resources on a long-term basis. Understanding of the water interactions can promote effective management of water resources in Shahu Lake.
EDITOR D. Koutsoyiannis

ASSOCIATE EDITOR D. Hughes  相似文献   

3.
Abstract

An investigation on the groundwater potentials of the Egbe-Mopa area in central Nigeria, underlain by the Basement Complex, is presented. The investigation involved mapping of the subsurface by use of vertical electrical soundings; measurement of depth to groundwater; and evaluation of hydraulic conductivity, transmissivity and yield by means of pumping test interpretation. The results indicate subsurface units that range from three to five resistivity layers; depth to groundwater of 0–10 m; overburden thickness of 3–16 m; hydraulic conductivity of 6.2?×?10?6 to 3.4?×?10?4 m/s; transmissivity of 4.3?×?10?7 to 2?×?10?3 m2/s; and groundwater yield of 0.2–2.5 L/s. The hydraulic head assessments revealed a general northward groundwater flow direction. The study identified three aquifer potential types, of high, medium and low productivity, respectively. Based on the longitudinal conductance of the overburden units, four distinct Aquifer Protective Capacity zones were delineated, namely, poor, weak, moderate and good.

Citation Okogbue, C.O. and Omonona, O.V., 2013. Groundwater potential of Egbe-Mopa basement area, central Nigeria. Hydrological Sciences Journal, 58 (4), 826–840.  相似文献   

4.
Groundwater provides an important source of water for maize cultivation where the water table is shallow in the semi-arid Hailiutu River catchment of the Maowusu Desert on the Erdos Plateau in Northwest China. A HYDRUS-1D model of the unsaturated flow beneath a maize (Zea mays L.) field was calibrated and validated with measured soil water contents at various depths during the maize growing period from 30 April to 1 October 2011, and from 23 May to 27 September 2012, respectively. The model computed the actual maize evapotranspiration (ETa) as 580 mm during the whole growing period from 30 April to 1 October 2011. The groundwater contribution to ETa was calculated to be 220 mm, accounting for 38% of maize water use during the growing season in 2011. When the groundwater level drops below a depth of 157 cm, maize can no longer use groundwater for transpiration. The irrigation water requirement increases with the increase of groundwater table depth. These results are very important for managing crop irrigation in the area.
EDITOR D. Koutsoyiannis

ASSOCIATE EDITOR L. Ruiz  相似文献   

5.
Knowledge of aquifer parameters is essential for management of groundwater resources. Conventionally, these parameters are estimated through pumping tests carried out on water wells. This paper presents a study that was conducted in three villages (Tumba, Kabazi, and Ndaiga) of Nakasongola District, central Uganda to investigate the hydrogeological characteristics of the basement aquifers. Our objective was to correlate surface resistivity data with aquifer properties in order to reveal the groundwater potential in the district. Existing electrical resistivity and borehole data from 20 villages in Nakasongola District were used to correlate the aquifer apparent resistivity (ρ e) with its hydraulic conductivity (K e), and aquifer transverse resistance (TR) with its transmissivity (T e). K e was found to be related to ρ e by; $ {\text{Log }}(K_{\text{e}} ) = - 0.002\rho_{\text{e}} + 2.692 $ . Similarly, TR was found to be related to T by; $ {\text{TR}} = - 0.07T_{\text{e}} + 2260 $ . Using these expressions, aquifer parameters (T c and K c) were extrapolated from measurements obtained from surface resistivity surveys. Our results show very low resistivities for the presumed water-bearing aquifer zones, possibly because of deteriorating quality of the groundwater and their packing and grain size. Drilling at the preferred VES spots was conducted before the pumping tests to reveal the aquifer characteristics. Aquifer parameters (T o and K o) as obtained from pumping tests gave values (29,424.7 m2/day, 374.3 m/day), (9,801.1 m2/day, 437.0 m/day), (31,852.4 m2/day, 392.9 m/day). The estimated aquifer parameter (T c and K c) when extrapolated from surface geoelectrical data gave (7,142.9 m2/day, 381.9 m/day), (28,200.0 m2/day, 463.4 m/day), (19,428.6 m2/day, 459.2 m/day) for Tumba, Kabazi, and Ndaiga villages, respectively. Interestingly, the similarity between the K c and K o pairs was not significantly different. We observed no significant relationships between the T c and T o pairs. The root mean square errors were estimated to be 18,159 m2/day and 41.4 m/day.  相似文献   

6.
Delineating hydrologic and pedogenic factors influencing groundwater flow in riparian zones is central in understanding pathways of water and nutrient transport. In this study, we combined two‐dimensional time‐lapse electrical resistivity imaging (ERI) (depth of investigation approximately 2 m) with hydrometric monitoring to examine hydrological processes in the riparian area of FD‐36, a small (0.4 km2) agricultural headwater basin in the Valley and Ridge region of east‐central Pennsylvania. We selected two contrasting study sites, including a seep with groundwater discharge and an adjacent area lacking such seepage. Both sites were underlain by a fragipan at 0.6 m. We then monitored changes in electrical resistivity, shallow groundwater, and nitrate‐N concentrations as a series of storms transitioned the landscape from dry to wet conditions. Time‐lapse ERI revealed different resistivity patterns between seep and non‐seep areas during the study period. Notably, the seep displayed strong resistivity reductions (～60%) along a vertically aligned region of the soil profile, which coincided with strong upward hydraulic gradients recorded in a grid of nested piezometers (0.2‐ and 0.6‐m depth). These patterns suggested a hydraulic connection between the seep and the nitrate‐rich shallow groundwater system below the fragipan, which enabled groundwater and associated nitrate‐N to discharge through the fragipan to the surface. In contrast, time‐lapse ERI indicated no such connections in the non‐seep area, with infiltrated rainwater presumably perched above the fragipan. Results highlight the value of pairing time‐lapse ERI with hydrometric and water quality monitoring to illuminate possible groundwater and nutrient flow pathways to seeps in headwater riparian areas.  相似文献   

7.
Rainwater, groundwater and soil-water samples were analysed to assess groundwater geochemistry and the origin of salinity in the Ochi-Narkwa basin of the Central Region of Ghana. The samples were measured for major ions and stable isotopes (δ18O, δ2H and δ13C). The Cl? content in rainwater decreased with distance from the coast. The major hydrochemical facies were Na-Cl for the shallow groundwaters and Ca-Mg-HCO3, Na-Cl and Ca-Mg-Cl-SO4 for the deep groundwaters. Groundwater salinization is caused largely by halite dissolution and to a minor extent by silicate weathering and seawater intrusion. Stable isotope composition of the groundwaters followed a slope of 3.44, suggesting a mixing line. Chloride profiles in the soil zone revealed the existence of salt crusts, which support halite dissolution in the study area. A conceptual flow model developed to explain the mechanism of salinization showed principal groundwater flow in the NW–SE direction.
EDITOR D. Koutsoyiannis

ASSOCIATE EDITOR K. Heal  相似文献   

8.
Abstract

A sand dune area, ~50 km2 in size, the only source of freshwater in the coastal zone of Prakasham district, Andhra Pradesh, India, is bounded by marine sediments in the northwest, and the Bay of Bengal in the southeast. Measurements of groundwater level, hydrochemistry and stable isotopes for three years facilitated the identification of the aquifer response to drought and intense cyclonic storms. There was no major change in hydrochemistry and isotope values between drought and highly saturated conditions, except in a few wells in the northwest. During drought, the groundwater remained fresh, although the levels dipped to 2–5 m b.m.s.l., signifying no saline water ingression (no measurable bromide). Based on the field observations, resistivity soundings, electrical conductivity and groundwater level change due to pumping, the existence of impermeable boundaries in the northwest and southeast are hypothesized. Thus, the existing hydrogeological settings appear to be inhibiting the movement of the freshwater–saline water interface into the freshwater zone.
Editor D. Koutsoyiannis  相似文献   

9.
Coastal groundwater discharge (CGD) plays an important role in coastal hydrogeological systems as they are a water resource that needs to be managed, particularly in wetland areas. Despite its importance, identifying and monitoring CGD often presents physical and logistical constraints, restraining the application of more traditional submarine groundwater discharge surveying techniques. Here we investigate the capability of electrical resistivity imaging (ERI) in the Peníscola wetland (Mediterranean coast, Spain). ERI surveying made it possible to identify and delineate an ascending regional groundwater flow of thermal and Ra‐enriched groundwater converging with local flows and seawater intrusion. The continuous inputs of Ra‐rich groundwater have induced high activities of Ra isotopes and 222Rn into the marsh area, becoming among the highest previously reported in wetlands and coastal lagoons. Geoelectrical imaging enabled inferring focused upward discharging areas, leaking from the aquifer roof through a confining unit and culminating as spring pools nourishing the wetland system. Forward modelling over idealized subsurface configurations, borehole datasets, potentiometric records from standpipe piezometers, petrophysical analysis, and four natural and independent tracers (224Ra, 222Rn, temperature and salinity) permitted assessing the geoelectrical model and a derived hydrogeological pattern. The research highlights the potential of ERI to improve hydrogeological characterization of subsurface processes in complex contexts, with different converging flows. Additionally, a hydrogeological conceptual model for a groundwater‐fed coastal wetland was proposed, based on the integration of surveying datasets. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

10.
Abstract

The multi-layered Jeffara de Gabes aquifer system is greatly influenced by tectonics. This system is limited at the base and laterally by evaporite layers and has lateral contacts with the sebkhas (salt flats). The groundwater in this aquifer is characterized by high salinity (3–10 g L-1). Multivariate statistical analysis and a geochemical approach were applied to determine the influence of the evaporite layers and sebkhas on the hydrochemical quality of the Jeffara de Gabes aquifer, and to understand the processes governing its salinity. According to these methods, and based in part on the Sr2+/Ca2+ ratio, it is demonstrated that the strong salinity of the groundwater is due to interactions between water and the evaporite layers that act as a substratum of this aquifer, as well as saltwater intrusion from the sebkhas. Moreover, the medium- to poor-quality groundwaters are characterized by geochemical interactions: cationic exchange and the precipitation/dissolution process of minerals in the aquifer formations.

Editeur Z.W. Kundzewicz

Citation Ben Alaya, M., Zemni, T., Mamou, A. et Zargouni, F., 2014. Acquisition de salinité et qualité des eaux d’une nappe profonde, Tunisie: approche statistique et géochimique. Hydrological Sciences Journal, 59 (2), 395–419.  相似文献   

11.
Geophysical methods were applied for hydrogeological targets in many countries including Vietnam. This paper presents results of using complex geophysical techniques as well as 2D electrical resistivity imaging (ERI), vertical electrical sounding (VES), very low frequency (VLF), and seismic refraction for geological structure investigation for locating the aquifers and assessing the hydrogeological conditions for groundwater potential in industrial zones of North Hanoi, Vietnam. The locations of two aquifers are determined by their depth and thickness on the basis of resistivity and seismic velocity values which were proved by stratifications of three boreholes to 40–60 m of depth on the study area. There are connections from surface water to shallow aquifer by hydraulic windows, as follows from VLF data. The deeper aquifer can be considered as a potential groundwater supply, but the water level is descending in time, as shown by hydrological monitoring. However, with careful use and by reducing sources of pollution, groundwater can continue to be an important natural resource for future.  相似文献   

12.
Abstract

Preferential flow pathways in a fractured aquifer may yield abrupt reductions of the water velocity in a well. We propose a new device for measuring low (5–13 cm d-1) velocities in wells originating from fractures at different depths. The presented flowmeter has been applied in a well in the Bari (southern Italy) fractured aquifer. In the same well, the horizontal flowmeter velocity (9.6 cm d-1) at 0.5 m depth was compared with velocity (8 cm d-1) derived from a field tracer test, providing a value 16.5% higher. Moreover, the flowmeter measurements at 1.5 m depth gave a horizontal velocity of 7.2 cm d-1, which is 11% less than water flow velocity estimated from the field test. The new flowmeter implements the tracer point-dilution method in a plastic (PVC) pipe by causing the water flow to pass through an artificial filter. Laboratory calibration tests have confirmed the good performance of the proposed flowmeter technique, even for water flow up to 300 cm d-1. The flowmeter was sensitive to 0.1 cm d-1, with a detection limit of 1.5 cm d-1, i.e. half the measurable flow velocity of existing flowmeters in wells.

Editor D. Koutsoyiannis; Associate editor S. Grimaldi  相似文献   

13.
Abstract

This study evaluates an over-exploited aquifer (Balasor, India) and also explores the possibilities of sustainable management using several statistical approaches. First, bootstrap analysis indicates that groundwater pumping has resulted in the reduction of mean cultivated area as the average irrigation capacity per bore well dropped from 3.74 ha to 1.5 ha within a period of 10 years of operation. However, modelling the groundwater levels using the seasonal autoregressive integrated moving average (SARIMA) procedure showed no evidence of large-scale groundwater withdrawals. The derived models can be used for water table forecasting and also for infilling the missing observations. The empirical relationship among pumping test results indicated that well depth and aquifer thickness significantly influence the discharge from the aquifer. This discharge may have encouraged the resource-rich farmers to exploit the lower aquifer. Based on a contour plot, the zone of groundwater exploitation was estimated to vary from 25 to 60 m below the surface. Therefore, a uniform aquifer exploitation policy needs to be implemented to curb the vertical competition in exploiting the aquifer and to develop sustainable management of the groundwater.

Citation Panda, D. K. & Kumar, A. (2011) Evaluation of an over-used coastal aquifer (Orissa, India) using statistical approaches. Hydrol. Sci. J. 56(3), 486–497.  相似文献   

14.
Population growth and changing climate continue to impact on the availability of natural resources. Urbanization of vulnerable coastal margins can place serious demands on shallow groundwater. Here, groundwater management requires definition of coastal hydrogeology, particularly the seawater interface. Electrical resistivity imaging (ERI) appears to be ideally suited for this purpose. We investigate challenges and drivers for successful electrical resistivity imaging with field and synthetic experiments. Two decades of seawater intrusion monitoring provide a basis for creating a geo-electrical model suitable for demonstrating the significance of acquisition and inversion parameters on resistivity imaging outcomes. A key observation is that resistivity imaging with combinations of electrode arrays that include dipole–dipole quadrupoles can be configured to illuminate consequential elements of coastal hydrogeology. We extend our analysis of ERI to include a diverse set of hydrogeological settings along more than 100 km of the coastal margin passing the city of Perth, Western Australia. Of particular importance are settings with: (1) a classic seawater wedge in an unconfined aquifer, (2) a shallow unconfined aquifer over an impermeable substrate, and (3) a shallow multi-tiered aquifer system over a conductive impermeable substrate. We also demonstrate a systematic increase in the landward extent of the seawater wedge at sites located progressively closer to the highly urbanized center of Perth. Based on field and synthetic ERI experiments from a broad range of hydrogeological settings, we tabulate current challenges and future directions for this technology. Our research contributes to resolving the globally significant challenge of managing seawater intrusion at vulnerable coastal margins.  相似文献   

15.
Bacteria and viruses are ubiquitous in subterranean aquatic habitats. Bacterial abundance is known to vary with depth in aquifers; however, whether viral abundance varies with depth is less well known. Here we use flow cytometry (FCM) to enumerate bacteria and virus‐like particles (VLP) from groundwater depth profiles. Groundwater samples were obtained from a set of nested piezometers from depths of 15, 30, 45, 60, 80, and 90 m and bacteria and VLP abundances were determined in purged aquifer water and unpurged water at each slot depth. Mean bacterial abundance (cells / mL) was not significantly different in unpurged water (3.2 × 105) compared to purged water (1.4 × 105); however, mean VLP abundance (particles / mL) was significantly greater in unpurged water (4.4 × 105) compared to purged water (2.3 × 105). Purged water was used to investigate the aquifer depth profile and bacterial and VLP abundances were observed to vary significantly between depths. The virus‐bacteria ratio was determined and was observed to steadily increase with depth. Overall, our data indicate the dynamic nature of bacterial and viral abundances in subsurface environments which should be considered when designing groundwater microbial sampling methodologies.  相似文献   

16.
ABSTRACT

Floodplains are composed of complex depositional patterns of ancient and recent stream sediments, and research is needed to address the manner in which coarse floodplain materials affect stream–groundwater exchange patterns. Efforts to understand the heterogeneity of aquifers have utilized numerous techniques typically focused on point-scale measurements; however, in highly heterogeneous settings, the ability to model heterogeneity is dependent on the data density and spatial distribution. The objective of this research was to investigate the correlation between broad-scale methodologies for detecting heterogeneity and the observed spatial variability in stream/groundwater interactions of gravel-dominated alluvial floodplains. More specifically, this study examined the correlation between electrical resistivity (ER) and alluvial groundwater patterns during a flood event at a site on Barren Fork Creek, in the Ozark ecoregion of Oklahoma, USA, where chert gravels were common both as streambed and as floodplain material. Water table elevations from groundwater monitoring wells for a flood event on 1–5 May 2009 were compared to ER maps at various elevations. Areas with high ER matched areas with lower water table slope at the same elevation. This research demonstrated that ER approaches were capable of indicating heterogeneity in surface water–groundwater interactions, and that these heterogeneities were present even in an aquifer matrix characterized as highly conductive. Portions of gravel-dominated floodplain vadose zones characterized by high hydraulic conductivity features can result in heterogeneous flow patterns when the vadose zone of alluvial floodplains activates during storm events.
EDITOR D. Koutsoyiannis; ASSOCIATE EDITOR X. Chen  相似文献   

17.
ABSTRACT

A modelling study was undertaken to quantify effects that the climate likely to prevail in the 2050s might have on water quality in two contrasting UK rivers. In so doing, it pinpointed the extent to which time series of climate model output, for some variables derived following bias correction, are fit for purpose when used as a basis for projecting future water quality. Working at daily time step, the method involved linking regional climate model (HadRM3-PPE) projections, Future Flows Hydrology (rainfall–runoff modelling) and the QUESTOR river network water quality model. In the River Thames, the number of days when temperature, dissolved oxygen, biochemical oxygen demand and phytoplankton exceeded undesirable values (>25°C, <6 mg L?1, >4 mg L?1 and >0.03 mg L?1, respectively) was estimated to increase by 4.1–26.7 days per year. The changes do not reflect impacts of any possible change in land use or land management. In the River Ure, smaller increases in occurrence of undesirable water quality are likely to occur in the future (by 1.0–11.5 days per year) and some scenarios suggested no change. Results from 11 scenarios of the hydroclimatic inputs revealed considerable uncertainty around the levels of change, which prompted analysis of the sensitivity of the QUESTOR model to simulations of current climate and hydrology. Hydrological model errors were deemed of less significance than those associated with the derivation and downscaling of driving climatic variables (rainfall, air temperature and solar radiation). Errors associated with incomplete understanding of river water quality interactions with the aquatic ecosystem were found likely to be more substantial than those associated with hydrology, but less than those related to climate model inputs. These errors are largely a manifestation of uncertainty concerning the extent to which phytoplankton biomass is controlled by invertebrate grazers, particularly in mid-summer; and the degree to which this varies from year to year. The quality of data from climate models for generating flows and defining driving variables at the extremes of their distributions has been highlighted as the major source of uncertainty in water quality model outputs.
EDITOR A. Castellarin; ASSOCIATE EDITOR X. Fang  相似文献   

18.
Abstract

A new structured approach is presented to derive groundwater baseline conditions, in this case for a dolomitic limestone aquifer suffering from salinization and other anthropogenic impacts. It builds on the HydroChemical System Analysis (HCSA) to map different groundwater bodies (hydrosomes) and hydrochemical zones within them, each of which show significant differences in baseline conditions. It also comprises a rigorous elimination scheme for samples affected by bias or pollution. The method is applied to the Damour coastal aquifer system, south of Beirut (Lebanon). Concentrations of Cl, Cl/Br, 2H, 18O and Ca/Sr were used to discern five hydrosomes and to determine mixing ratios. The dominant hydrochemical facies was (sub)oxic, calcareous and salinized, indicating a very low reduction capacity of the aquifer system, strong dissolution of dolomitic limestone and clear traces of seawater encroachment. The method proposed was capable of filtering out baseline conditions for 16 main constituents, 64 trace elements and two isotopes.  相似文献   

19.
An area of about 30 km2 located in Ain Jouhra, south of Rabat, Morocco, was the subject of a geoelectric resistivity investigation. The main goal of the investigation was the assessment of the groundwater potential of the uppermost aquifer. The aquifer conditions such as depth, thickness and boundaries were also investigated. The obtained apparent resistivity curves were first analysed qualitatively and classified using simple curve shapes. Thereafter, the data were converted to resistivity and thickness pairs semi‐quantitatively by means of master curves and then quantitatively by computer modelling using ATO and Winsev software (Zohdy, 1989; Zohdy and Bisdrof, 1989). Lithological control from the available single well with a stratigraphic log aided in the correlation of the resistivity values to different rock units. Three different AB‐spacing iso‐resistivity maps, an isopach map of the main groundwater‐bearing horizon, the depth to the aquifer substratum map and five geoelectric cross‐sections were constructed. The interpretation of these soundings indicates the presence of an unconfined to semi‐confined sandy aquifer with relatively important extent and varying thickness. The maximal thickness of the aquifer is recorded in the central part of the investigated area and is thinning southwards to pinch out farther to the south. Geophysical as well as field data indicate a hydraulic connection between the upper and deeper aquifers. Indeed, the two aquifers are separated from each other by a marly substratum that is indicated throughout the area by the lowest values of the interpreted true resistivity. The value of this resistivity varies laterally, most likely due to the lateral variation in the shale‐to‐sand ratio. The altitude of the substratum decreases towards the north, and increases southwards. Regarding the availability of the groundwater in the study area, zones with high potential are theoretically expected to occur in the central part where the transversal resistance is greatest. However, sufficient water supply and high flow rates from wells intended to produce restrictively from the most upper aquifer are not likely to exist. This conclusion, which seems to be very pessimistic, is evidenced from two real field and experimental observations. The first is the rapid fall of the level of Gharnoug lake, despite the ongoing feeding by three wells. Hence, the amount of water level drop cannot be accounted for by the evaporation alone. That means that the deeper aquifer is continuously draining the upper aquifer at a high flow rate. Very low rates are recorded in all the wells that penetrated only the upper aquifer, the exception being the well that reached deeper into the lower aquifer. The flow rate in this lower aquifer measured 18 litre s?1. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

20.
1D resistivity sounding and 2D resistivity imaging surveys were integrated with geological and hydrochemical data to assess the aquifer vulnerability and saltwater intrusion in the north of Nile Delta, Egypt. In the present study, the El-Gharbyia main drain was considered as a case study to map the sand bodies within the upper silt and clay aquitard. Twenty Schlumberger soundings and six 2D dipole-dipole profiles were executed along one profile close to the western side of the main drain. In addition, 14 groundwater samples and 4 surface water samples from the main drain were chemically analyzed to obtain the major and trace elements concentrations.The results from the resistivity and hydrochemical data were used to assess the protection of the groundwater aquifer and the potential risk of groundwater pollution. The inverted resistivities and thicknesses of the layers above the aquifer layer were used to estimate the integrated electrical conductivity (IEC) that can be used for quantification of aquifer vulnerability. According to the aquifer vulnerability assessment of an underlying sand aquifer, the southern part of the area is characterized by high vulnerability zone with slightly fresh to brackish groundwater and resistivity values of 11-23 Ω.m below the clay cap. The resistivity sections exhibit some sand bodies within the clay cap that lead to increase the recharging of surface waste water (650 mg/l salinity) and flushing the upper part of underlying saltwater aquifer. The region in the north has saltwater with resistivity less than 6 Ω.m and local vulnerable zones within the clay cap. The inverted 2D dipole-dipole profiles in the vulnerable zones, in combination with drilling information have allowed the identification of subsoil structure around the main drain that is highly affected by waste water.  相似文献   

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