共查询到20条相似文献，搜索用时 31 毫秒
1.
D. C.-F. Shih 《Stochastic Environmental Research and Risk Assessment (SERRA)》1999,13(1-2):85-99
This study uses the cyclical frequency to develop the mathematical relationship between hydraulic diffusivity and spectral
density functions calculated from groundwater level variation. Such relationship can be applied to (1) unsteady state, one-dimensional
confined aquifer with time-dependent water level on both end boundaries, and (2) linearized unconfined aquifer with or without
vertical recharge. The spectral density functions of groundwater fluctuations are largely affected by the spectral density
functions obtained from time-dependent end boundaries and their cross-spectral density functions. Hydraulic diffusivity of
an aquifer can be solved by type-curve matching technique at a specified frequency band under the conditions of (1) confined
aquifer having equal time-dependent boundaries on both ends, (2) unconfined aquifer having equal time-dependent boundaries
on both ends with surface recharge, and (3) unconfined aquifer subjected to surface recharge but neglecting the water table
fluctuations on both end boundaries. 相似文献
2.
Abdulrahman Al-Charideh 《水文科学杂志》2013,58(2):452-467
Abstract Chemical and isotopic data of groundwater of the Upper Cretaceous aquifer in the Orontes basin, Syria, have been used to assess the groundwater geochemistry, the origin of groundwater recharge and groundwater residence time. The chemical data indicate that dissolution of evaporite minerals is the main process controlling groundwater mineralization. The composition of stable isotopes δ18O and δ2H, together with 14C activity, reflect the existence of three different groups: (a) groundwater in the Coastal Mountains with δ18O of –6.65‰, quite similar to modern-day precipitation, and high 14C (>50 pmC); (b) groundwater in the unconfined aquifer of the Hama Uplift, which has δ18O of –5.52‰ and 14C near 20 pmC, and is recharged locally; and (c) groundwater from the confined aquifer of the Homs Depression, which is characterized by more depleted δ18O,, –8.01‰, and low 14C (<7 pmC), and might be recharged in the northern piedmont of the Anti-Lebanon Mountains. The distinctive isotope signatures of the latter two groups indicate different recharge elevations and palaeoclimatic effects. The low recharge rate of the groundwater in the Hama Uplift aquifer, and the even slower recharge rate in the Homs Depression aquifer, are reflected by groundwater 14C residence times of 5 and over 22 Ka BP, respectively. Editor D. Koutsoyiannis Citation Al-Charideh, A., 2013. Recharge and mineralization of groundwater of the Upper Cretaceous aquifer in Orontes basin (Syria). Hydrological Sciences Journal, 58 (2), 452–467. 相似文献
3.
A recently developed approach to carbon isotope methodology (process recognition via isotope diagrams) is applied in a multidisciplinary study of precipitation‐recharged aquifers of the lowlands–plains area of the Manawatu (south‐west North Island). Urban and rural areas rely on groundwater from the upper levels of a deep basin sequence comprising marine and terrestrial sediments of Pleistocene age. Hydrochemical and isotopic (18O, 3H, 13C and 14C) data are merged with known details of geology and hydrogeology to reveal two separate confined aquifers within the depth range to 200 m. The shallower of these, below unconfined, locally recharged groundwater, is recharged on the foothills of the Ruahine Range to the north‐east of the study area; flow direction is NE–SW. The deeper confined aquifer is recharged on the Tararua Range to the immediate east; flow direction essentially is transverse (SE–NW) to that in the shallower aquifer. Two processes are identified as dominant contributors to concentration and isotopic composition of dissolved inorganic carbon (DIC), namely addition of CO2 from decay of organic materials and carbonate dissolution. Limitations of carbon isotope methods in determining residence times are illustrated by the data. Although the confined groundwater is essentially tritium‐free, only a few samples showed conclusive evidence of significant ageing on the time‐scale of 14C. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
4.
The study area is located on the western part of the alluvium‐filled gap between the Rajmahal hills on the west and the Garo hills on the east. Groundwater occurs under unconfined condition in a thick zone of saturation within the Quaternary alluvial sediments. Three hydrochemical facies with distinct characteristics have been identified which are dominated in general by alkaline earths and weak acids. The major‐ion chemistry of the area is controlled by weathering of silicate minerals, rainfall recharge, ion‐exchange processes and anthropogenic activities such as irrigation return flow and the application of inorganic fertilizers and pesticides. A stoichiometric approach suggests that mineral dissolution and anthropogenic activities contribute 79% and 21% of the total cations dissolved in groundwater. Principal component analysis (PCA) of 42 groundwater samples using 13 chemical parameters indicates that the combined processes of recharge of groundwater from rainfall, sediment water interaction, groundwater flow, infiltration of irrigation return water (which is arsenic rich due to the use of arsenic‐bearing pesticides, wood preservatives, etc. and the pumping of arsenic‐rich groundwater for agriculture purpose), oxidation of natural or anthropogenic organic matter and the reductive dissolution of ferric iron and manganese oxides play a key role in the evolution of groundwater in the study area. Factor 2 scores, associated with the infiltration of irrigation return water and spatial distribution of arsenic concentration reveal that the groundwater of the municipal area will not be affected by arsenic in the future in spite of heavy groundwater abstraction. Another PCA with geologic, geomorphic, anthropogenic, geochemical and landuse factors indicates that arsenic concentration in groundwater increases with increasing area of mango orchards, sand lithofacies and nitrate and decreases with increasing distance of paleochannel from the monitored well and depth of bore wells. High loading on nitrate may be attributed to the use of fertilizer, pesticides, etc. in mango orchards and agricultural land. High loadings on log pCO2, mango orchards (with negative sign) and phosphate (with positive sign) indicate that mango orchards provide the organic waste material which is decomposed to form organic carbon. The organic carbon undergoes oxidative carbon degeneration by different oxidants and increases the concentration of CO2 in the aquifer. The reducing condition thus developed in the aquifer helps to dissolve the arsenic adsorbed on iron hydroxide or oxy‐hydroxide coated margins of sand, iron rich heavy mineral grain margins, clay minerals and Fe–Mn concretions present in the aquifer matrix. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
5.
To understand the spatial distribution and the possible sources of high ammonium concentration in the unconfined coastal aquifer of the Po River Delta lowland (Italy), a detailed characterization of inorganic nitrogen species was completed. A total of 59 boreholes were drilled to collect core samples and groundwater samples of the aquifer. Among them, four piezometers, located along a representative flow line, were chosen to monitor the inorganic nitrogen concentrations with depth. Ammonium is the prevalent nitrogen inorganic species in groundwater, and its concentration increases with depth and salinity. Very high ammonium concentrations are found in coincidence with peaty sediments in the salinized anoxic aquifer and in the low‐lying aquitard. In particular, the elevated ammonium concentration derives from mineralization of organic matter present in fine sediments deposited in paleo‐marsh environments. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
6.
Groundwater in coastal areas is commonly disturbed by tidal fluctuations. A two‐dimensional analytical solution is derived to describe the groundwater fluctuation in a leaky confined aquifer system near open tidal water under the assumption that the groundwater head in the confined aquifer fluctuates in response to sea tide whereas that of the overlying unconfined aquifer remains constant. The analytical solution presented here is an extension of the solution by Sun for two‐dimensional groundwater flow in a confined aquifer and the solution by Jiao and Tang for one‐dimensional groundwater flow in a leaky confined aquifer. The analytical solution is compared with a two‐dimensional finite difference solution. On the basis of the analytical solution, the groundwater head distribution in a leaky confined aquifer in response to tidal boundaries is examined and the influence of leakage on groundwater fluctuation is discussed. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
7.
A mathematical model is developed to investigate the effects of tidal fluctuations and leakage on the groundwater head of leaky confined aquifer extending an infinite distance under the sea. The leakages of the offshore and inland aquitards are two dominant factors controlling the groundwater fluctuation. The tidal influence distance from the coast decreases significantly with the dimensionless leakage of the inland aquitard (ui). The fluctuation of groundwater level in the inland part of the leaky confined aquifer increases significantly with the dimensionless leakage of the offshore aquitard (uo). The influence of the tidal propagation parameter of an unconfined aquifer on the head fluctuation of the leaky confined aquifer is comparatively conspicuous when ui is large and uo is small. In other words, ignoring water table fluctuation of the unconfined aquifer will give large errors in predicting the fluctuation, time lag, and tidal influence distance of the leaky confined aquifer for large ui and small uo. On the contrary, the influence of the tidal propagation parameter of a leaky confined aquifer on the head fluctuation of the leaky confined aquifer is large for large uo and small ui. 相似文献
8.
In variably confined carbonate platforms, impermeable confining units collect rainfall over large areas and deliver runoff to rivers or conduits in unconfined portions of platforms. Runoff can increase river stage or conduit heads in unconfined portions of platforms faster than local infiltration of rainfall can increase groundwater heads, causing hydraulic gradients between rivers, conduits and the aquifer to reverse. Gradient reversals cause flood waters to flow from rivers and conduits into the aquifer where they can dissolve limestone. Previous work on impacts of gradient reversals on dissolution has primarily emphasized individual caves and little research has been conducted at basin scales. To address this gap in knowledge, we used legacy data to assess how a gradient of aquifer confinement across the Suwannee River Basin, north‐central Florida affected locations, magnitudes and processes of dissolution during 2005–2007, a period with extreme ranges of discharge. During intense rain events, runoff from the confining unit increased river stage above groundwater heads in unconfined portions of the platform, hydraulically damming inputs of groundwater along a 200 km reach of river. Hydraulic damming allowed allogenic runoff with SICAL < ?4 to fill the entire river channel and flow into the aquifer via reversing springs. Storage of runoff in the aquifer decreased peak river discharges downstream and contributed to dissolution within the aquifer. Temporary storage of allogenic runoff in karst aquifers represents hyporheic exchange at a scale that is larger than found in streams flowing over non‐karst aquifers because conduits in karst aquifers extend the area available for exchange beyond river beds deep into aquifers. Post‐depositional porosity in variably confined carbonate platforms should thus be enhanced along rivers that originate on confining units. This distribution should be considered in models of porosity distribution used to manage water and hydrocarbon resources in carbonate rocks. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
9.
Konstantin W. Scheihing 《水文科学杂志》2018,63(8):1255-1261
The effect of pressure-driven groundwater recharge signal propagation in the Andean-Atacamenian environment is investigated by assessing a record of 15 years of water table fluctuations of an unconfined–confined aquifer system. Based on a singular spectrum analysis of water table time series, it is shown that, in the given case, groundwater levels in the central Atacama Desert are hydraulically controlled by two distant recharge areas associated with the Andes. The maximum observed range of the pressure signal propagation is ~50 km over an elevation difference of more than 3000 m at a lag of ~25 months. Several findings indicate that an often-cited study misinterpreted a water level rise at the same site as an in-situ alluvial fan recharge. Thus, the effect’s impact on groundwater dynamics in complex aquifer systems can easily be overlooked. Singular spectrum analysis could be of use to investigate pressure effects at hydrologically comparable sites. 相似文献
10.
John Spoelstra Kristen A. Leal Natalie D. Senger Sherry L. Schiff Ryan Post 《Ground water》2021,59(5):658-670
The stable isotope ratios of groundwater sulfate (34S/32S, 18O/16O) are often used as tracers to help determine the origin of groundwater or groundwater contaminants. In agricultural watersheds, little is known about how the increased use of sulfur as a soil amendment to optimize crop production is affecting the isotopic composition of groundwater sulfate, especially in shallow aquifers. We investigated the isotopic composition of synthetic agricultural fertilizers and groundwater sulfate in an area of intensive agricultural activity, in Ontario, Canada. Groundwater samples from an unconfined surficial sand aquifer (Lake Algonquin Sand Aquifer) were analyzed from multi-level monitoring wells, riverbank seeps, and private domestic wells. Fertilizers used in the area were analyzed for sulfur/sulfate content and stable isotopic composition (δ18O and/or δ34S). Fertilizers were isotopically distinct from geological sources of groundwater sulfate in the watershed and groundwater sulfate exhibited a wide range of δ34S (−6.9 to +20.0‰) and δ18O (−5.0 to +13.7‰) values. Quantitative apportionment of sulfate sources based on stable isotope data alone was not possible, largely because two of the potential fertilizer sulfate sources had an isotopic composition on the mixing line between two natural geological sources of sulfate in the aquifer. This study demonstrates that, when sulfate isotope analysis is being used as a tracer or co-tracer of the origin of groundwater or of contaminants in groundwater, sulfate derived from synthetic fertilizer needs to be considered as a potential source, especially when other parameters such as nitrate independently indicate fertilizer impacts to groundwater quality. 相似文献
11.
Pumping wells are common in coastal aquifers affected by tides. Here we present analytical solutions of groundwater table or head variations during a constant rate pumping from a single, fully-penetrating well in coastal aquifer systems comprising an unconfined aquifer, a confined aquifer and semi-permeable layer between them. The unconfined aquifer terminates at the coastline (or river bank) and the other two layers extend under tidal water (sea or tidal river) for a certain distance L. Analytical solutions are derived for 11 reasonable combinations of different situations of the L-value (zero, finite, and infinite), of the middle layer’s permeability (semi-permeable and impermeable), of the boundary condition at the aquifer’s submarine terminal (Dirichlet describing direct connection with seawater and no-flow describing the existence of an impermeable capping), and of the tidal water body (sea and tidal river). Solutions are discussed with application examples in fitting field observations and parameter estimations. 相似文献
12.
Evaluation of nitrate levels in groundwater under agricultural fields in two pilot areas in central Chile: A hydrogeological and geochemical approach 总被引：2，自引：0，他引：2 
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下载免费PDF全文 The aim of this study is to evaluate the impact of the application of industrial fertilizers and liquid swine manure in groundwater in two pilot agricultural areas, San Pedro and Pichidegua, which have been under long‐term historic use of fertilizers. A comprehensive hydrogeological investigation was carried out to define the geology and the groundwater flow system. Chemical and isotopic tools were used to evaluate the distribution and behavior of the nitrate in the groundwater. The isotopic tools included δ18O, δ2H, and 3H, which provide information about the origin and residence time of the groundwater; δ15N‐NO3? and δ18O‐NO3?, which provide information about nitrate sources and processes that can affect nitrate along the groundwater flow system. The application rate of liquid manure and other fertilizers all together with land uses was also evaluated. The hydrogeological investigation identified the presence of a confined aquifer underneath a thick low‐permeability aquitard, whose extension covers most of the two study areas. The nitrate concentration data, excepting a few points in zones located near recharge areas in the upper part of the basins and lower areas at the valley outlets (San Pedro), showed nitrate concentration below 10 mgN/L at the regional scale. The isotope data for nitrate showed no influence of the liquid swine manure in the groundwater at the regional scale, except for the high part of the basins and the outlet of the San Pedro valley, which are areas fertilized by manure. This data showed that the regional aquifer on both pilot study areas is protected by the thick low‐permeability aquitard, which is playing an important role on nitrate attenuation. Evidence of denitrification was also found on both shallow and deep groundwater in the Pichidegua site. This study showed that a comprehensive hydrogeological characterization complemented by chemical and isotope data is key for understanding nitrate distribution and concentration in aquifers from areas with intensive agriculture activities. 相似文献
13.
This article investigates the quantity of submarine groundwater discharge (SGD) from a coastal multi‐layered aquifer system in response to constant rainfall infiltration. The system comprises an unconfined aquifer, a leaky confined aquifer and an aquitard between them and terminates at the coastline. An approximate analytical solution is derived based on the following assumptions: (i) flow is horizontal in the aquifers and vertical in the aquitard, and (ii) flow in the unconfined aquifer is described by nonlinear Boussinesq equation. The analytical solution is compared with numerical solutions of the strictly two‐dimensional nonlinear model to validate the model assumptions used for the analytical solution. The SGD from the leaky confined aquifer increases with the inland rainfall infiltration recharge and the specific leakage of aquitard. The maximum SGD ranges from 1·87 to 10·37 m3 per day per meter of shoreline when rainfall infiltration ranges from 18·2 to 182 mm/year and the specific leakage of aquitard varies from 10?9 to 10?1 l/day. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
14.
In eastern England the Chalk aquifer is covered by extensive Pleistocene deposits which influence the hydraulic conditions and hydrochemical nature of the underlying aquifer. In this study, the results of geophysical borehole logging of groundwater temperature and electrical conductivity and depth sampling for major ion concentrations and stable isotope compositions (δ18O and δ2H) are interpreted to reveal the extent and nature of the effective Chalk aquifer of north Norfolk. It is found that the Chalk aquifer can be divided into an upper region of fresh groundwater, with a Cl concentration of typically less than 100 mg l−1, and a lower region of increasingly saline water. The transition between the two regions is approximately 50 m below sea-level, and results in an effective aquifer thickness of 50–60 m in the west of the area, but less than 25 m where the Eocene London Clay boundary is met in the east of the area. Hydrochemical variations in the effective aquifer are related to different hydraulic conditions developed in the Chalk. Where the Chalk is confined by low-permeability Chalky Boulder Clay, isotopically depleted groundwater (δ18O less than −7.5‰) is present, in contrast to those areas of unconfined Chalk where glacial deposits are thin or absent (δ18O about −7.0‰). The isotopically depleted groundwater is evidence for groundwater recharge during the late Pleistocene under conditions when mean surface air temperatures are estimated to have been 4.5°C cooler than at the present day, and suggests long groundwater residence times in the confined aquifer. Elevated molar Mg:Ca ratios of more than 0.2 resulting from progressive rock-water interaction in the confined aquifer also indicate long residence times. A conceptual hydrochemical model for the present situation proposes that isotopically depleted groundwater, occupying areas where confined groundwater dates from the late Pleistocene, is being slowly modified by both diffusion and downward infiltration of modem meteoric water and diffusive mixing from below with an old saline water body. 相似文献
15.
Abstract This paper develops a new analytical solution for the aquifer system, which comprises an unconfined aquifer on the top, a semi-confined aquifer at the bottom and an aquitard between them. This new solution is derived from the Boussinesq equation for the unconfined aquifer and one-dimensional leaky confined flow equation for the lower aquifer using the perturbation method, considering the water table over-height at the remote boundary. The head fluctuation predicted from this solution is generally greater than the one solved from the linearized Boussinesq equation when the ratio of the tidal amplitude to the thickness of unconfined aquifer is large. It is found that both submarine groundwater discharges from upper and lower aquifers increase with tidal amplitude–aquifer thickness ratio and may be underestimated if the discharge is calculated based on the average head fluctuation. The effects of the aquifer parameters and linearization of the Boussinesq equation on the normalized head fluctuation are also investigated. Editor D. Koutsoyiannis; Associate editor J. Simunek Citation Chuang, M.-H., Mahdi, A.-A. and Yeh, H.-D., 2012. A perturbation solution for head fluctuations in a coastal leaky aquifer system considering water table over-height. Hydrological Sciences Journal, 57 (1), 162–172. 相似文献
16.
A general solution for groundwater flow in an estuarine's leaky aquifer system after considering aquifer anisotropy 下载免费PDF全文
下载免费PDF全文 This paper presents an analytical model for describing the tidal effects in a two‐dimensional leaky confined aquifer system in an estuarine delta where ocean and river meet. This system has an unconfined aquifer on top and a confined aquifer on the bottom with an aquitard in between the two. The unconfined and confined aquifers interact with each other through leakage. It was assumed that the aquitard storage was negligible and that the leakage was linearly proportional to the head difference between the unconfined and confined aquifers. This model's solution was based on the separation of variables method. Two existing solutions that deal with the head fluctuation in one‐dimensional or two‐dimensional leaky confined aquifers are shown as special cases in the present solution. Based on this new solution, the dynamic effect of the water table's fluctuations can be clearly explored, as well as the influence of leakage on the behaviour of fluctuations in groundwater levels in the leaky aquifer system. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
17.
Groundwater evolution and mean water age inferred from hydrochemical and isotopic tracers in a tropical confined aquifer 下载免费PDF全文
下载免费PDF全文 Pedro Villegas Vanesa Paredes Teresita Betancur Jean D. Taupin Luis E. Toro 《水文研究》2018,32(14):2158-2175
The coastal confined aquifer in the Gulf of Urabá (Colombia) is an important water source for the banana agro‐industry as well as for urban and rural communities. However, the main processes controlling recharge and mixing in the aquifer are still poorly understood. Hydrochemical analyses and stable isotope monitoring were conducted to (a) determine groundwater recharge origin, mean groundwater age, and the main processes governing groundwater chemistry and the potential mixing of marine water and the influence of diffusive processes from the two surrounding aquitard layers. Hydrochemical data indicate that the main processes affecting the dissolved chemical composition include cation exchange, dissolution of carbonated and CO2, and silicate weathering. δ18O and δ2H compositions combined with 14C data highlight the differences in climatic conditions between the recharge zone and the confined section of the aquifer, which is close to the Atlantic Ocean. Groundwater samples with 14C ages from recent to 28,300 years BP show a depleted isotopic trend ranging from ?6.43‰ to ?9.14‰ in δ18O and from ?43.2‰ to ?65.7‰ in δ2H. The most depleted δ18O and δ2H compositions suggest a cooler recharge climate than the current conditions (corresponding to the last glacial period of the late Pleistocene). Depleted δ13C values in the total dissolved inorganic carbon indicate the existence of organic material oxidation processes within the geologic formation. These results can be used or transferred to enhance groundwater modelling efforts in other confined coastal aquifers of South America where scarcity of long‐term monitoring data limits water resources planification under a changing climate. 相似文献
18.
为深入理解井水位同震响应机理,本文开展了向完整井-松散含水层系统输入由不同频率和振幅（加速度）组成的正弦波荷载的振动台实验。以实验模型为物理模型,建立了振动作用下松散承压含水层中孔隙水压力响应的流固耦合模型和含水层水流与井流的相互作用模型,并运用多物理场耦合模拟软件COMSOL Multiphysics对实验过程进行了数值模拟。实验中观测到的四种典型水位变化形态与野外场地同震井水位变化形态相似。数值模拟结果显示,本研究建立的数学模型能较好地反映松散承压含水层中孔隙水压力和水位的响应情况。本文研究对解释地下水同震响应机制、岩体渗流稳定性和安全问题具有重要意义。 相似文献
19.
Using chlorofluorocarbons (CFCs) and tritium (3H) to estimate groundwater age and flow velocity in Hohhot Basin,China 下载免费PDF全文
下载免费PDF全文 Jun Liu Zongyu Chen Wen Wei Yilong Zhang Zhenghong Li Fuliang Liu Hualiang Guo 《水文研究》2014,28(3):1372-1382
The concentrations of chlorofluorocarbons (CFC‐11, CFC‐12 and CFC‐113) and tritium (3H) content in groundwater were used to date groundwater age, delineate groundwater flow systems and estimate flow velocity in the Hohhot basin. The estimated young groundwater age is fallen in the bracket of 21 ~ 50 a and indicates the presence of two different age profiles and flow systems in the shallow groundwater system. Older age waters occur under the topographically low areas, where the aquifer is double‐layer aquifer system consisting of shallow unconfined‐semi‐confined aquifer and deep confined aquifer. This reflects long flow paths associated with regional flow. Groundwater (range from 21 to 34 years) in the north piedmont and east hilly areas, where the aquifer is a single‐layer aquifer consisting of alluvial fans, are typically younger than those in the low areas. The combination of CFCs dating with hydrogeological information indicates that both local and regional flow systems are present at the basin. The regional groundwater flow mainly flows from the north and east to the southwest, the local groundwater flow system occurs nearby the Hohhot city. The mean regional groundwater flow velocity of the shallow groundwater is estimated about 0.73 km/a. These findings can aid in refining hydrogeological conceptual model of the study area. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
20.
Abstract Knowledge of the processes that control nitrate migration and its geochemical evolution in the subsurface are fundamental for the regional management of polluted aquifers. In this paper, the spatial distribution and transient variations of nitrate concentrations, associated with manure fertilization, are used to depict hydrogeological dynamics within the sedimentary aquifer system of la Plana de Vic in the Osona region of Spain. Flow systems are identified from geological, hydraulic head, hydrochemical and isotopic data, and by considering nitrate itself as a tracer that indicates how flow paths are modified by human pressures. In this area, nitrates move through fractured aquitards in flows induced by groundwater pumping. Moreover, the lack of casing in the boreholes permits a mixing of groundwater from distinct layers inside the wells, which negates any benefits from the low-nitrate groundwater found in the deepest aquifer layers. Therefore, impacts on groundwater quality are related to intensive manure fertilization as well as to inadequate well construction and exploitation strategies. Citation Menció, A., Mas-Pla, J., Otero, N. & Soler, A. (2011) Nitrate as a tracer of groundwater flow in a fractured multilayered aquifer. Hydrol. Sci. J. 56(1), 108–122. 相似文献