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1.
A significant component of domestic demand for water of urban areas located in the Gangetic plains is met by heavy pumping of groundwater. The present study is focused on the Patna municipal area, inhabited by 17 million people and spanning over 134 km2, where entire urban water demand is catered from pumping by wells of various capacities and designs. The present study examines the nature of the aquifer system within the urban area, the temporal changes in the water/piezometric level and the recharge mechanism of the deeper aquifers. The aquifer system is made up of medium-to-coarse unconsolidated sand, lying under a ~40-m-thick predominantly argillaceous unit holding 8- to 13-m-thick localised sand layers and continues up to 220 m below ground. Groundwater occurs under semi-confined condition, with transmissivity of aquifers in 5,500–9,200 m2 day?1 range. Hydraulic head of the deeper aquifer remains in 9–19 m range below ground, in contrast to 1–9 m range of that of the upper aquitard zone. The estimated annual groundwater extraction from the deeper aquifer is ~212.0 million m3, which has created a decline of 3.9 m in the piezometric level of the deeper aquifer during the past 30 years. Unregulated construction of deep tube wells with mushrooming of apartment culture may further exacerbate the problem. The sand layers within the aquitard zone are experiencing an annual extraction of 14.5 million m3 and have exhibited stable water level trend for past one and half decades. This unit is recharged from monsoon rainfall, besides contribution from water supply pipe line leakage and seepage from unlined storm water drains.  相似文献   

2.
Transmissivity (T) is a basic hydraulic parameter of an aquifer that is utilized in most groundwater flow equations to understand the flow dynamics and is generally estimated from pumping tests. However, the cost of performing a large number of aquifer tests is expensive and time consuming. The fact that specific capacity (S c) is correlated with hydraulic flow properties of aquifers simplifies parameter estimation mainly because specific capacity values are more abundant in groundwater databases than values of transmissivity and they offer another approach to estimate hydraulic parameters of aquifers. In this study, an empirical relation is derived using 214 pairs of transmissivity and specific capacity values that are obtained from pumping tests conducted on water wells penetrating the complex volcanic aquifers of Upper Awash Basin, central Ethiopia. Linear and logarithmic regression functions have been performed and it is found that the logarithmic relationship predicting transmissivity from specific capacity data has a better correlation (R = 0.97) than the linear relationship (R = 0.79). The two parameters are log-normally distributed, in which the logarithmic relation is also better statistically justified than the linear relation. Geostatistical estimations of the transmissivity were made using different inputs and methods. Measured and supplemented transmissivity data obtained from estimates using the derived empirical relation were krigged and cokrigged, spherical and exponential models were fitted to the experimental variograms. The cross-validation results showed that the best estimation is provided using the kriging procedure, the transmissivity field represented by the measured transmissivity data and the experimental variogram fitted with the exponential model. Based on the geostatistical approach, the transmissivity map of the aquifer is produced, which will be used for groundwater flow modeling of the study area that will follow this analysis.  相似文献   

3.
Aquifers within the Pampa del Tamarugal Basin (Atacama Desert, northern Chile) are the sole source of water for the coastal city of Iquique and the economically important mining industry. Despite this, the regional groundwater system remains poorly understood. Although it is widely accepted that aquifer recharge originates as precipitation in the Altiplano and Andean Cordillera to the east, there remains debate on whether recharge is driven primarily by near-surface groundwater flow in response to periodic flood events or by basal groundwater flux through deep-seated basin fractures. In addressing this debate, the present study quantifies spatial and temporal variability in regional-scale groundwater flow paths at 20.5°S latitude by combining a two-dimensional model of groundwater and heat flow with field observations and δ18O isotope values in surface water and groundwater. Results suggest that both previously proposed aquifer recharge mechanisms are likely influencing aquifers within the Pampa del Tamarugal Basin; however, each mechanism is operating on different spatial and temporal scales. Storm-driven flood events in the Altiplano readily transmit groundwater to the eastern Pampa del Tamarugal Basin through near-surface groundwater flow on short time scales, e.g., 100–101 years, but these effects are likely isolated to aquifers in the eastern third of the basin. In addition, this study illustrates a physical mechanism for groundwater originating in the eastern highlands to recharge aquifers and salars in the western Pampa del Tamarugal Basin over timescales of 104–105 years.  相似文献   

4.
Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low δ2H and δ18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7?×?10?4 cm3 (STP) g–1?±?2.2 % which is approximately four orders of magnitude higher than expected due to solubility equilibrium with the atmosphere. Groundwater age dating based on estimated in situ production and terrigenic flux of helium provides a groundwater residence time of ～107 years. Although fluid exchange between the deep basal aquifer system and the upper aquifer layers is generally impeded by confining clay layers and lignite, this study’s geochemical data suggest, for the first time, that deep circulating fluids penetrate shallow aquifers in the locality of fault zones, implying  that sub-vertical fluid flow occurs along faults in the LRE. However, large hydraulic-head gradients observed across many faults suggest that they act as barriers to lateral groundwater flow. Therefore, the geochemical data reported here also substantiate a conduit-barrier model of fault-zone hydrogeology in unconsolidated sedimentary deposits, as well as corroborating the concept that faults in unconsolidated aquifer systems can act as loci for hydraulic connectivity between deep and shallow aquifers. The implications of fluid flow along faults in sedimentary basins worldwide are far reaching and of particular concern for carbon capture and storage (CCS) programmes, impacts of deep shale gas recovery for shallow groundwater aquifers, and nuclear waste storage sites where fault zones could act as potential leakage pathways for hazardous fluids.  相似文献   

5.
In the Afram Plains area, groundwater is the main source of water supply for most uses. The area is underlain by aquifers of the southern Voltaian sedimentary basin, which are predominantly sandstones, mudstones, conglomerates and shale. Ordinary least squares regression analysis using 41 well-test data from aquifers in the Afram Plains portion of the Voltaian system reveals that transmissivity, T, exists in a non-linear relationship with specific capacity, Sc. The analysis reveals that T = 0.769Sc1.075 with R 2 = 0.83 for aquifers in the area. The mudstone/conglomerate aquifer in the area appears to be the most variable in terms of both specific capacity and transmissivity with transmissivity ranging from 0.18 to 197.7 m2/day and 0.5 and 148.5 m3/day/m, respectively. Horizontal fractures and joints resulting from secondary fracturing appear to be the main determinants of both transmissivity and specific capacity in the area. PHREEQC modeling and mineral stability diagrams indicate that groundwater quality in the Afram Plains area is controlled by the incongruent weathering of silicate minerals in the aquifers. These processes concentrate calcium, sodium, magnesium, potassium, bicarbonate ion and quartz, leading to calcite, dolomite and aragonite supersaturation at most locations. Hierarchical cluster analysis performed on the raw chemical data reveals two main water types or facies: the calcium–sodium–chloride–bicarbonate facies, and the magnesium–potassium–sulfate–nitrate facies for the southern and northern sections of the Afram Plains area, respectively.  相似文献   

6.
 The central Ganga Basin is one of the major groundwater reservoirs in India. The Kali-Ganga sub-basin is a micro watershed of the central Ganga Basin, containing a number of productive aquifers. A detailed hydrogeological investigation was carried out, which reveals the occurrence of a single-tier aquifer system down to 163 m bgl (metres below ground level), but at places it is interleaved with clay layers; thus imparting it a two-to three-tier aquifer system. These aquifers are unconfined to confined in disposition. The transmissivity, storage coefficient and hydraulic conductivity are determined as 2178 m2/day, 1.12×10–5 and 120 m/day, respectively. The groundwater of the basin is fresh, of an alkali-bicarbonate type and is suitable for irrigation and domestic use. However, in certain areas, extensive agricultural activities, and domestic and industrial effluents have caused some deterioration of groundwater quality. This study contains data of where the concentration of Fe, Pb, Cd, Cr and Ni are higher than the permissible limits, which may be hazardous to public health. Received: 2 March 2000 · Accepted: 3 July 2000  相似文献   

7.
 Quaternary alluvial aquifers in the paleo Pennar delta region of Andhra Pradesh (Long. 80°0′ and 80°12′; Lat. 14°40′ and 14°20′) constitute an important coastal strip, with potential fresh groundwater resources and several well fields in operation. The lineament patterns and traces of paleo channels provide basic information on the configuration and boundaries of paleo delta and the possible neotectonic movements in the region. The paleo delta region is essentially characterized by freshwater aquifer systems at the near-surface depths, (up to 50 m from ground level) with transmissivity values in the system ranging from 1200 to 2500 m2/day. This groundwater system has been subjected to heavy draft situation over the last two decades, parlicularly near the outer rim of the delta where an unlined brackish-water canal runs parallel to the coast imparting chloride contamination to the adjoining fresh aquifers. A two-dimensional solute transport model solution was applied to assess chloride migration rates inland under different hydraulic stresses, combining finite difference solution of flow equation and the method of characteristic solution of solute transport equation. Groundwater flow and chloride migration patterns/rates were obtained for different simulated stress events in the delta system, and measures required to protect the freshwater resources ara outlined. Received: 2 January 1997 · Accepted: 4 November 1997  相似文献   

8.
In the Djerid-Nefzaoua region, southern Tunisia, about 80% of agricultural and domestic water supply is provided by the complex terminal (CT) aquifer. However, 20% of this demand is provided by other hydraulically connected aquifers, namely the continental intercalaire (CI) and the Plio-Quaternary (PQ). Overexploitation of the CT aquifer for agricultural practices has contributed to the loss of the artesian condition and the decline of groundwater level which largely increased the downward leakage from the shallow PQ aquifer. Excess irrigation water concentrates at different rates in the irrigation channels and in the PQ aquifer itself. Then, it returns to the CT aquifer and mixes with water from the regional flow system, which contributes to the salinization of the CT groundwater. A geochemical and isotopic study had been undertaken over a 2-years period in order to investigate the origin of waters pumped from the CT aquifer with an emphasis on its hydraulic relationships with the underlying and the overlying CI and PQ aquifers. Geochemistry indicates that groundwater samples collected from different wells show an evolution of the water types from Na-Cl to Ca-SO4-Cl. Dissolution of halite, gypsum and anhydrite-bearing rocks is the main mechanism that leads to the salinization of the groundwater. Isotopic data indicate the old origin of all groundwater in the aquifer system. Mixing and evaporation effects characterizing the CT and the PQ aquifers were identified using δ2H and δ18O relationship and confirmed by the conjunction of δ2H with chloride concentration.  相似文献   

9.
Hydrogeologic framework of the Maku area basalts, northwestern Iran   总被引：1，自引：0，他引：1  
The Maku area in northwestern Iran is characterized by young lava flows which erupted from Mount Ararat in Turkey. These fractured volcanic rocks overlie alluvium associated with pre-existing rivers and form a good basalt-alluvium aquifer over an area of 650 km2. Groundwater discharge occurs from 12 large springs, ranging from 20 to 4,000 L s?1, and from some extraction wells. Permian and Oligo-Miocene age limestones along the northern boundary of the Bazargan and Poldasht Plains basalts are intensively karstified and groundwater from these high lands easily enters the basalt-alluvium aquifers. The transmissivity of the basalt-alluvium aquifer ranges from 24 to 870 m2 d?1, indicating heterogeneity. Groundwater of the aquifer is a sodium-bicarbonate and mixed cation-bicarbonate type and the concentration of fluoride is higher than the universal maximum admissible concentrations for drinking. In order to determine the chemical composition and identify the source of the high fluoride concentrations in the groundwater of the basaltic area, water samples from the springs, wells and rivers were analyzed. The results indicate that the high fluoride water enters the study area from the Sari Su River.  相似文献   

10.
Pico, the youngest island of the Azores archipelago, is composed of basaltic volcanic deposits less than 300,000 years old. The principal aquifer system consists mainly of recent lava flows that are very permeable and whose head is influenced by tidal fluctuations. Groundwater abstraction is almost entirely by drilled wells. The hydraulic gradient is very low, about 10–4, which agrees with observations made on similar volcanic islands. Groundwater also occurs in perched-water bodies, but the spring discharge from them is very low, about 10–3 L/s. The transmissivity of the volcanic rocks ranges from 9.44×10–3 to 3.05×10–1 m2/s, indicating the heterogeneity of the aquifers. The hydraulic diffusivity, estimated from observations of the effects of tidal fluctuations, also confirms the high permeability of the aquifer system; the average value is higher than published values for other volcanic islands. A mixing process for fresh water and seawater, often coupled with ion-exchange mechanisms, explains the groundwater composition, which is mainly of the sodium-chloride type. The water salinity influences the groundwater quality, resulting in a chloride content that exceeds the recommended chloride limit in 91% of the wells . Water–rock interactions are dominant in the chemical evolution of the perched water, which is characterized by bicarbonate-anion type water. Electronic Publication  相似文献   

11.
A numerical groundwater model of the weathered crystalline aquifer of Ursuya (a major water source for the north-western Pyrenees region, south-western France) has been computed based on monitoring of hydrological, hydrodynamic and meteorological parameters over 3 years. The equivalent porous media model was used to simulate groundwater flow in the different layers of the weathered profile: from surface to depth, the weathered layer (5?·?10?8?≤?K?≤?5?·? 10?7 m s?1), the transition layer (7?·?10?8?≤?K?≤?1?·? 10?5 m s?1, the highest values being along major discontinuities), two fissured layers (3.5?·?10?8?≤?K?≤?5?·?? 10?4 m s?1, depending on weathering profile conditions and on the existence of active fractures), and the hard-rock basement simulated with a negligible hydraulic conductivity (K = 1 10 ?9 ). Hydrodynamic properties of these five calculation layers demonstrate both the impact of the weathering degree and of the discontinuities on the groundwater flow. The great agreement between simulated and observed hydraulic conditions allowed for validation of the methodology and its proposed use for application on analogous aquifers. With the aim of long-term management of this strategic aquifer, the model was then used to evaluate the impact of climate change on the groundwater resource. The simulations performed according to the most pessimistic climatic scenario until 2050 show a low sensitivity of the aquifer. The decreasing trend of the natural discharge is estimated at about ?360 m3 y?1 for recharge decreasing at about ?5.6 mm y?1 (0.8 % of annual recharge).  相似文献   

12.
The rapid expansion of agriculture, industries and urbanization has triggered unplanned groundwater development leading to severe stress on groundwater resources in crystalline rocks of India. With depleting resources from shallow aquifers, end users have developed resources from deeper aquifers, which have proved to be counterproductive economically and ecologically. An integrated hydrogeological study has been undertaken in the semi-arid Madharam watershed (95 km2) in Telangana State, which is underlain by granites. The results reveal two aquifer systems: a weathered zone (maximum 30 m depth) and a fractured zone (30–85 m depth). The weathered zone is unsaturated to its maximum extent, forcing users to tap groundwater from deeper aquifers. Higher orders of transmissivity, specific yield and infiltration rates are observed in the recharge zone, while moderate orders are observed in an intermediate zone, and lower orders in the discharge zone. This is due to the large weathering-zone thickness and a higher sand content in the recharge zone than in the discharge zone, where the weathered residuum contains more clay. The NO3 ? concentration is high in shallow irrigation wells, and F? is high in deeper wells. Positive correlation is observed between F? and depth in the recharge zone and its proximity. Nearly 50 % of groundwater samples are unfit for human consumption and the majority of irrigation-well samples are classed as medium to high risk for plant growth. Both supply-side and demand-side measures are recommended for sustainable development and management of this groundwater resource. The findings can be up-scaled to other similar environments.  相似文献   

13.
A regional lithostratigraphic and hydraulic interpretation is presented for the upper 0–300 m of the Benin Formation where groundwater is abstracted in the Rivers State, Nigeria.The aquifers are predominantly sand beds with minor clays, lignite, and conglomerate intercalations. The sands are very fine to coarse grained, subangular to subrounded, poor to fairly well sorted and mostly lithic arenites. A maximum thickness greater than 50 m is developed in places and vertical stacking is common. Most of the conglomerate beds have a matrix support fabric and appear restricted to the east as the lignite beds. An east-west trending belt, about central to the state, seems to contain more clay interbeds.The transmissivity values for the aquifers range from 1.05 × 10–2 to 11.3 × 10–2 m2/sec, while the coefficient of storage varies between 1.07 × 10–4 and 3.53 × 10–4 and specific capacity values lie between 19.01 and 139.8 m3/h/m drawdown. These values suggest that the aquifers have very good capacity to transmit groundwater. The static water level map shows a north-to-south regional groundwater flow pattern except in the northeast (Imo River catchment area) where the flow is northeast to southwest. The groundwater quality is very good and compares favorably with WHO standards for drinking water. However, relatively high iron and chloride values are localized in time and space.Deposition of the aquifer materials is thought to have occurred in alluvial fan, fluvial channel, tidal channel, intertidal flat, beach, and related microenvironments.  相似文献   

14.
The combined effects of low rainfall, groundwater withdrawal in excess of 300 GL/year and reduced recharge in areas covered by pine plantations has caused the water table in a sandy unconfined aquifer on the Gnangara Mound in Western Australia to drop by up to 5 m and aquifer storage to decline by about 500 GL over the last 20 years. Groundwater has become acidic in areas of high drawdown, with pH values typically being less than 5.0 at the water table, and elevated concentrations of SO4 2?, Al, Fe, Zn, Cu, Ni and Pb. Trends of increasing acidity and base cation concentrations in deep water supply wells in the Mirrabooka wellfield indicate that about 0.7 keq/ha/year of base cations are being leached from soil within cones of depression of pumping wells. These results indicate that the assessment of the sustainable yields of aquifers under conditions of low rainfall needs to consider geochemical interactions between groundwater, aquifer sediments, soils and vegetation, and not be just based on aquifer hydraulics and water-balance changes.  相似文献   

15.
The carbonate aquifers of Lora and Mingo form part of the hydrogeological unit of Sierra de Estepa (SE Spain). By means of time series analysis and a 1D numerical groundwater model, groundwater exploitation was quantified and the mean annual recharge in both systems was estimated (2001–2004). During this period, the Lora and Mingo aquifers received an average groundwater recharge of 0.29 × 106 m3/year and 0.14 × 106 m3/year, respectively, whereas an average of 0.34 × 106 m3/year and 0.21 × 106 m3/year, respectively, was extracted. These conditions led to a conspicuous lowering of the water table in both systems. In addition, the analysis of the evolution of the main hydrogeochemical parameters of the groundwater showed that the increased pumping rates produced an increase in total dissolved solids, and chloride and sodium ions in both aquifers. In the case of the Lora aquifer, the only ion that presented decreased levels was nitrate. The results show that groundwater pumping in both aquifers should not exceed the mean annual recharge of 0.29 × 106 m3/year and 0.14 × 106 m3/year in the Lora and Mingo aquifers, respectively. Nevertheless, it would be advisable to reduce pumping rates to below these values in order to restore piezometric levels and improve groundwater quality for different uses in the future.  相似文献   

16.
This paper reviews, compiles and comprehensively analyzes spatial variations in hydrogeologic characteristics of shallow and deep groundwater aquifers in Kathmandu Valley. To estimate transmissivity (T) (and then hydraulic conductivity) as a function of specific capacity (SC), an empirical relationship between T and SC is developed for shallow and deep aquifer. The results show that T and SC are log linearly related by an equation T = 0.8857(SC)1.1624 [R 2 = 0.79] in shallow and T = 1.1402(SC)1.0068 [R 2 = 0.85] in deep aquifer. The estimated T ranges from 163 to 1,056 m2/day in shallow aquifer and 22.5 to 737 m2/day in deep aquifer. Finally, mapping of spatial distribution in hydrogeologic characteristics (thickness, T, hydraulic conductivity and storage coefficient) in shallow and deep aquifers are accomplished using ArcGIS9.2 and such maps would be useful in delineating potential areas for groundwater development and simulating groundwater flow in the aquifer system.  相似文献   

17.
The use of isotope tracers as a tool for assessing aquifer responses to intensive exploitation is demonstrated and used to attain a better understanding of the sustainability of intensively exploited aquifers in the North China Plain. Eleven well sites were selected that have long-term (years 1985–2014) analysis data of isotopic tracers. The stable isotopes δ18O and δ2H and hydrochemistry were used to understand the hydrodynamic responses of the aquifer system, including unconfined and confined aquifers, to groundwater abstraction. The time series data of 14C activity were also used to assess groundwater age, thereby contributing to an understanding of groundwater sustainability and aquifer depletion. Enrichment of the heavy oxygen isotope (18O) and elevated concentrations of chloride, sulfate, and nitrate were found in groundwater abstracted from the unconfined aquifer, which suggests that intensive exploitation might induce the potential for aquifer contamination. The time series data of 14C activity showed an increase of groundwater age with exploitation of the confined parts of the aquifer system, which indicates that a larger fraction of old water has been exploited over time, and that the groundwater from the deep aquifer has been mined. The current water demand exceeds the sustainable production capabilities of the aquifer system in the North China Plain. Some measures must be taken to ensure major cuts in groundwater withdrawals from the aquifers after a long period of depletion.  相似文献   

18.
The hydrogeologic and hydraulic characteristics of a lateritic terrain in West Bengal, India, were investigated. Test drilling was conducted at ten sites and grain-size distribution curves (GSDCs) were prepared for 275 geologic samples. Performance evaluation of eight grain-size-analysis (GSA) methods was carried out to estimate the hydraulic conductivity (K) of subsurface formations. Finally, the GSA results were validated against pumping-test data. The GSDCs indicated that shallow aquifer layers are coarser than the deeper aquifer layers (uniformity coefficient 0.19–11.4). Stratigraphy analysis revealed that both shallow and deep aquifers of varying thickness exist at depths 9–40 and 40–79 m, respectively. The mean K estimates by the GSA methods are 3.62–292.86 m/day for shallow aquifer layers and 0.97–209.93 m/day for the deeper aquifer layers, suggesting significant aquifer heterogeneity. Pumping-test data indicated that the deeper aquifers are leaky confined with transmissivity 122.69–693.79 m2/day, storage coefficient 1.01?×?10?7–2.13?×?10?4 and leakance 2.01?×?10?7–34.56?×?10?2 day?1. Although the K values yielded by the GSA methods are generally larger than those obtained from the pumping tests, the Slichter, Harleman and US Bureau Reclamation (USBR) GSA methods yielded reasonable values at most of the sites (1–3 times higher than K estimates by the pumping-test method). In conclusion, more reliable aquifers exist at deeper depths that can be tapped for dependable water supply. GSA methods such as Slichter, Harleman and USBR can be used for the preliminary assessment of K in lateritic terrains in the absence of reliable field methods.  相似文献   

19.
Groundwater sustainability assessment in coastal aquifers   总被引：1，自引：0，他引：1  
The present work investigates the response of shallow, coastal unconfined aquifers to anticipated overdraft conditions and climate change effect using numerical simulation. The groundwater flow model MODFLOW and variable density groundwater model SEAWAT are used for this investigation. The transmissivity and specific yield estimated from the existing database range from 10 to 810 m 2/day and 0.08% to 10.92% respectively. After successful calibration with Nash–Sutcliffe efficiency greater than 0.80, the values of horizontal hydraulic conductivity and specific yield of the unconfined aquifer were set in the range 1.85–61.90 m/day and 0.006–0.24 respectively. After validating the model, it is applied for forecasting the aquifer’s response to anticipated future scenarios of groundwater draft, recharge rate and sea level rise. The findings of the study illustrate that saltwater intrusion is intensified in the area adjoining the tidal rivers, rather than that due to the sea alone. Of all the scenarios simulated, the immense negative impact on groundwater quality emerges due to overdraft conditions and reduced recharge with the areal extent of seawater intrusion exceeding about 67% (TDS >1 kg/m 3). The study also arrives at the conclusion that, regional sea level rise of 1 mm/year has no impact on the groundwater dynamics of the aquifer.  相似文献   

20.
Globally, aquifers are suffering from large abstractions resulting in groundwater level declines. These declines can be caused by excessive abstraction for drinking water, irrigation purposes or industrial use. Basaltic aquifers also face these conflicts. A large flood basalt area (1.1?×?105 km2) can be found in the Northwest of the USA. This Columbia River Basalt Group (CRBG) consists of a thick series of basalt flows of Miocene age. The two major hydrogeological units (Wanapum and Grand Ronde formations) are widely used for water abstraction. The mean decline over recent decades has been 0.6 m year?1. At present day, abstraction wells are drying up, and base flow of rivers is reduced. At the eastern part of CRBG, the Moscow sub-basin on the Idaho/Washington State border can be found. Although a thick poorly permeable clay layer exists on top of the basalt aquifer, groundwater level dynamics suggest that groundwater recharge occurs at certain locations. A set of wells and springs has been monitored bi-weekly for 9 months for δ18O and δ2H. Large isotopic fluctuations and d-excess values close to the meteoric water line in some wells are indicating that recharge occurs at the granite/basalt interface through lateral flow paths in and below the clay. A soil moisture routing (SMR) model showed that most recharge occurs on the granitic mountains. The basaltic aquifer receives recharge from these sedimentary zones around the granite/basalt interface. The identification of these types of areas is of major importance for future managed-aquifer recharge solutions to solve problems of groundwater depletion.  相似文献   

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