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1.
Over a period of three hydrological years during which precipitation was highly variable, measurements of discharge, electrical conductivity, temperature and chemical components of the water at the Cañamero spring (southern Spain) were taken in order to characterise the hydrogeological functioning of the karst aquifer that it drains. The results obtained from analysis of the frequency distribution of electrical conductivity data revealed histograms with a plurimodal morphology (up to 5 modes) and a range of variation that increased with greater pluviometry during the study period. The discharge from this spring increased sharply a few days after major rainfall episodes and, when the discharge reached a value of approximately 3.73 m3/s, an overflow spring started to function. During high-water periods, there were sudden and large falls in EC, temperature and all the chemical components dissolved in the water. This high variability reflects the predominance of groundwater flow through karst drains, a typical feature of conduit flow systems. The considerable hydrochemical heterogeneity observed is caused by the mobilisation of important volumes of recharge waters from shallow areas of the aquifer (soil, epikarst) towards the discharge point, with greater participation of the unsaturated zone during high-water conditions, and a more active role played by the saturated zone during low-water conditions. In karst systems such as the one drained by the Cañamero spring, it is important to monitor several responses (hydrodynamic, hydrothermal, hydrochemical, etc.), with an appropriate sampling frequency and under different hydrometeorological conditions, in order to achieve an adequate hydrological characterisation. This is fundamental for planning, management and protection of groundwater in karst aquifers.  相似文献   

2.
The hydraulic behaviour of the karst aquifer in the Hubelj spring catchment area (SW Slovenia) was studied by using an indirect research method based on natural tracers. The variations of natural tracers (in precipitation and in groundwater) during the storm event made possible the separation of the Hubelj spring storm hydrograph by the three-component separation technique. The results produced information on the aquifer recharge, storage and discharge processes, as well as on the mechanisms that affected them. They verified the so-called epikarst hypothesis presuming that an important part of a karst aquifer recharge reaches rapidly and intensively from the epikarst zone. It was demonstrated that epikarst water could occupy up to 50% of the spring discharge during precipitation events. This phenomenon could have important consequences on protection and management of the problems of karst aquifers, including engineering problems in karst areas. With this respect the results could give way to new engineering ideas.  相似文献   

3.
The karst groundwater in northern China is an important source of water supply. Its capacity for self-renewal is a key factor affecting its sustainable use. The Pingyi–Feixian karst aquifer in central and southern Shandong Province is a typical karst water source, contributing 54% to the total groundwater taken from the region. In this study, 25 groups of water samples were collected from the Pingyi–Feixian karst aquifer in November 2013. The compositions of isotopes of tritium (3H), carbon-13 (13C), and carbon-14 (14C) were measured. As indicated by the tritium values between 7.1 and 12.2 TU, the Pingyi–Feixian karst groundwater is primarily originated from both historical atmospheric precipitation and modern precipitation. The 14C ages corrected by δ13C were between 146 and 5403 years. Specifically, the shallow groundwater is younger than deep groundwater. Groundwater age tends to increase along the flow path. The ages of the groundwater in recharge area were between 146 and 1348 years, while the ages of deep groundwater in flowing area were generally between 2000 and 4000 years. The ages of the groundwater in discharge area with little anthropic exploitation were larger than 4500 years, whereas these with large amounts of exploitation were less than 1500 years. The shallower the groundwater, the stronger its capacity for renewal. The renewable capacity of karst groundwater in discharge area was significantly affected by anthropic exploitation. The karst groundwater in the areas with less exploitation showed the weakest capacity, whereas that in the area with intensive exploitation was much older and had a stronger renewable capacity.  相似文献   

4.
The unique hydrogeology of karst makes the associated groundwater respond quickly to rainfall events and vulnerable to anthropogenic pollutions. In this study, high-frequency monitoring of spring discharge, temperature, electrical conductivity (EC) and pH, along with monthly hydrochemical and microbial analyses, was undertaken at the outlet of Laolondong karst underground river in Nanshan, southwestern China. The aim was to explore the environmental effects of the catchment’s urban area on the karst groundwater resources. The monitoring data of a tracer test and the response of discharge to rainfall events demonstrate that conduits and narrow fissures coexist in the Laolongdong karst aquifer. The EC, Na+, Cl? and SO42? values (840 μS/cm, 33.7, 38.6 and 137.2 μg/L, respectively), along with high concentrations of fecal coliform bacteria, at the outlet indicate considerable urban pollution in this area. The contaminants sulfate and nitrate showed different relationships with discharge and EC in different stages of a rainfall event. This behavior provided information about aquifer structure and the influence of transport properties. Meanwhile, the hydrological processes of groundwater flow could be modified by urbanization and result in increasing magnitude of urban floods in the underground river. In addition, sulfuric and nitric acids introduced by urbanization not only impact the karst groundwater quality, but also result in a significant perturbation to the carbon cycling system in the karst area.  相似文献   

5.
根据岩溶地下水的运动特征,提出了岩溶地下水压力波形成与传播的概念模型,运用灰色系统理论建立了岩溶地下水的水文模型,包括泉水流量对降水量水力响应时间的求解方法及泉水流量对降水量的响应模型,并以山西柳林泉为研究对象,建立了泉水流量对泉域内不同区域降水量的水力响应时间求解模型。结果表明,泉域南部岩溶裸露区的水力响应时间为1年;泉域北部岩溶覆盖区的水力响应时间为7年,所得结论与泉域地质构造一致。基于南、北二区的水力响应时间,建立了带有时滞的描述泉水流量与降水量关系的GM(1,3)模型,模型回代检验的平均误差为6.05%;模型预测检验的平均误差为12.19%。研究证明,岩溶地下水的运动过程是压力波的形成与传播过程,泉水流量是地下水系统对大气降水的响应;水力响应时间是反映岩溶地下水压力波特性的主要参数,通过它可以实现对岩溶地下水过程的定量化描述和含水层的非均质性识别,基于岩溶地下水压力波传播原理建立的泉水流量对泉域内降水的响应模型可以比较准确地模拟泉水流量,为岩溶地下水资源的开发利用和保护提供了基础资料。  相似文献   

6.
Hydrological modeling in the karst area,Rižana spring catchment,Slovenia   总被引：1，自引：1，他引：0  
Karst aquifers are known for their heterogeneity and irregular complex flow patterns which make them more difficult to model and demand specific modeling approaches. This paper presents one such approach which is based on a conceptual model. The model was applied in a karst area of the catchment of Rižana spring (200 km2). It is based on the MIKE SHE code and incorporates the main hydrological processes and geological features of the karst aquifer (diffuse and concentrated infiltration, allogenic recharge, quick and slow groundwater flow, shifting groundwater divides and groundwater outflow from the catchment area). Modeling of evapotranspiration and flow in the upper part of the unsaturated zone is more detailed. For the modeling of groundwater flow in the karst aquifer, a conceptual model was applied which uses drainage function for the simulation of groundwater flow through large conduits (karst channels and large fissures). The model was calibrated and validated against the observed Rižana spring discharge which represents a measured response of the aquifer. The results of validation show that the model is able to adequately simulate temporal evolution of the spring discharge, measured by Nash–Sutcliffe coefficient (0.82) as well as overall water balance.  相似文献   

7.
The water demand in arid regions is commonly covered by groundwater resources that date back to more humid periods of the Pleistocene and Holocene. Within the investigated arid part of SE Saudi-Arabia information about climate, groundwater levels, and pumping rates are only available for regions where groundwater extractions occur at present-day. For the prediction of the impact of long-term climate changes on groundwater resources an understanding of the hydrogeological and hydrological past and the development of the aquifers is necessary. Therefore, all available information about hydrology and hydrogeology for the past 10,000 years BP were collected and compiled to a conceptual model of the aquifer development on the Arabian Peninsula since the last Ice-Age. The climatic history was displayed by changes in precipitation, temperature and recharge during the mid-S and late Holocene. The hydrogeological development is described by groundwater ages, sea level fluctuations, movement of the coastline, and the development of sabkhas. The most sensitive parameter to describe the development of aquifer system is recharge. Present-day recharge was calculated with the hydrological model system HEC-HMS accounting for current precipitation, temperature, wind, soil types, and geomorphology. With respect to changes in precipitation and temperature over the past 10,000 years the temporal and spatial variability of groundwater recharge was calculated using empirical equations valid for semi-arid and arid settings. Further inflow into the groundwater system results from surface water infiltration in wadi beds, while natural outflow from the groundwater system occurs by discharge to the Gulf, evaporation from sabkhas, and spring discharge. Backward predictions can be verified by sedimentological observations of palaeo-river systems and lakes indicating that groundwater levels reached temporarily the surface under wetter climate conditions and 14C groundwater ages displaying groundwater residence times.  相似文献   

8.
Flow and solute transport monitoring in the karst aquifer in SW Slovenia   总被引：1，自引：0，他引：1  
The role of the unsaturated zone in the karst aquifer hydraulic behaviour was brought into focus in these studies of the catchment of the Hubelj spring (SW Slovenia). The variations of natural tracers in precipitation and in groundwater during a summer storm event made it possible to trace local flow and solute transport in the observed aquifer. The results produced data on the aquifer recharge, storage and discharge processes, as well as on mechanisms that affected them, which reflects a karst groundwater dynamics also at a regional scale. They point out the significance of effects of the fast preferential flow—epiflow that is the main factor controlling solute/contaminant transport towards the aquifer saturated zone. Numerous arguments indicate that the karst aquifer flow and solute transport mechanisms depend on the hydraulic behaviour of the epikarst zone.  相似文献   

9.
Measured concentrations of environmental tracers in spring discharge from a karst aquifer in the Shenandoah Valley, USA, were used to refine a numerical groundwater flow model. The karst aquifer is folded and faulted carbonate bedrock dominated by diffuse flow along fractures. The numerical model represented bedrock structure and discrete features (fault zones and springs). Concentrations of 3H, 3He, 4He, and CFC-113 in spring discharge were interpreted as binary dilutions of young (0–8  years) water and old (tracer-free) water. Simulated mixtures of groundwater are derived from young water flowing along shallow paths, with the addition of old water flowing along deeper paths through the model domain that discharge to springs along fault zones. The simulated median age of young water discharged from springs (5.7  years) is slightly older than the median age estimated from 3H/3He data (4.4  years). The numerical model predicted a fraction of old water in spring discharge (0.07) that was half that determined by the binary-dilution model using the 3H/3He apparent age and 3H and CFC-113 data (0.14). This difference suggests that faults and lineaments are more numerous or extensive than those mapped and included in the numerical model.  相似文献   

10.
娘子关泉水流量的GM(1,2)时滞预测模型   总被引：6，自引：0，他引：6  
娘子关泉位于山西省阳泉市平定娘子关附近,多年平均流量10. 93m3 /s,是我国北方最大的岩溶泉群。泉域西高东低,西部多为古生界二叠系、中生界三叠系砂页岩覆盖,大气降水入渗在这里形成浅层地下水,这些浅层水是深层岩溶含水层的间接补给水源; 泉域东部为岩溶裸露区,大气降水直接入渗补给深层岩溶水。由于岩溶泉域地质结构的复杂性和含水介质的多重性,泉域降水对泉水补给具有明显的灰色动态特征和时滞效应。本文应用灰色系统理论方法,建立了GM( 1, 2) 时滞模型,运用该模型对娘子关泉水流量进行了预测,结果与实际相接近。   相似文献   

11.
Sousan Spring emerges from the Keyno Anticline, Zagros Mountains (Iran), and the mean annual discharge is ~24 m3/s. Geological and hydrochemical evaluations suggest that the spring recharge is from the limestone Ilam-Sarvak Formation (Cretaceous) but the Mafaroon Fault, a major thrust feature, influences the regional groundwater flow path by juxtaposing other strata. Geological, geochemical, stable isotope and water balance studies were employed to interpret this behavior. Using the isotope data, the sources and elevations of the recharge area were found. Temporal variations of the isotopic data were compared with variations of electrical conductivity (EC). Unexpectedly, high EC was associated with a relative increase of discharge and depletion of δ18O. Several hypotheses were investigated and approximate water balance studies employed for validation. It was found that an elongated catchment on the Keyno Anticline plus a lesser catchment on a pair of parallel anticlines recharge the aquifer. While the long groundwater flow path along the Keyno Anticline plus guidance by Mafaroon Fault and the adjacent Garou shaly strata lead to increased EC in the Sousan Spring at the end of the dry season, a flow pulse from two adjoining anticlines (Mahalbakh and Shirgoon) arrives at the same time to increase the discharge and deplete the δ18O signal. Apparently the spring did not experience true base flow conditions during the recorded hydrological year. Although the spring response to specific precipitation events was similar to typical karst aquifers, standard interpretation of recession curves and related coefficients will not be practical at Sousan.  相似文献   

12.
在分析区域地质、水文地质条件及水化学同位素的基础上,研究了山西娘子关泉域岩溶水的SO42-、硫同位素分布特征。研究表明:（1）泉域西北、西南地区岩溶水的SO42-主要来源于石膏的溶解;（2）泉域中部汇流区岩溶水的SO42-含量高而δ34S值低,其中的SO42-主要来源于煤系矿坑水,这是因为温河、桃河及南川河沿岸的岩溶水接受了被矿坑水污染的河水的渗漏补给以及部分地区受到钻孔串层污染;（3）娘子关泉群中城西泉水中的SO42-主要来源于煤系矿坑水,而五龙泉和集泉站水中的SO42-主要来源于石膏的溶解;（4）泉域东北部及东部河流沿岸以外的地区,岩溶水中的SO42-主要来源于大气降水、石膏溶解,并受到所处地层岩性的影响。   相似文献   

13.
In order to study the function, hydrodynamic behavior, and hydraulic properties of the karst aquifers in Izeh, southwest Iran, time series analysis was applied to the precipitation, spring discharge, and piezometric head data of two representative karst systems of Zagros (Ilam-Sarvak and Asmari Formations). Time series analysis was applied to two karst aquifers, those of Asmari and Ilam-Sarvak Formations. The daily precipitations of anticlines were estimated based on the precipitation–elevation function which was applied on digital elevation model (DEM) of the area. The mean estimated daily precipitations were considered in bivariate time series analysis as input data of each karst system. The total length of time series was about 2.7 years, extending from May 2007 to December 2009. During the research, several one-parameter probe data loggers were installed, which daily measure the water surfaces in karst aquifers. Time series analysis was applied for describing Izeh karst aquifers with a focus on both univariate (autocorrelation and spectral analysis) and bivariate (cross-correlation, gain function, and coherency function) methods. The results show that Asmari karst aquifer in Kamarderaz Anticline has a large storage capacity. Because of lacking a well-organized karst network, in the Asmari karst aquifer, baseflow dominates with low contribution of quick-flow. In the Ilam-Sarvak karst aquifer (Shavish and Tanush Anticlines), the karstification occurred in fractures and small diameter conduits, which caused to quick-flow between dense limestone. The Ilam-Sarvak karst aquifer could be regarded as a transition between two extreme types of karst, e.g., highly karstified system and in the opposite, extremely diffused one. The analysis of well hydrograph in Ilam-Sarvak karst aquifer shows that the karst aquifer has a low storage capacity. Unlike Asmari karst aquifer, the fractures and small diameter conduits in Ilam-Sarvak karst aquifer are more enhanced, producing a better developed karst network. Contrary to the typical karst systems, however, diffuse flow and conduit flow coexist in the Asmari Formation.  相似文献   

14.
岩溶含水层具有高度的非均质性和各向异性,为定量识别济南泉域岩溶含水层发育状况,通过选取泉域岩溶水补给区和排泄区的地下水位动态数据,采用相关分析和频谱分析,研究其对降雨补给的响应特征.地下水位-降雨量的自相关和互相关分析表明,系统对降雨输入信号的敏感程度自补给区至排泄区逐渐降低,但记忆作用逐渐增强.相位分析结果表明泉域地下水位对降雨信号的响应存在滞后现象,自补给区至排泄区滞后时间逐渐延长,补给区地下水位与降雨具有更好的线性相关性.交叉振幅分析结果表明补给区地下水流中快速流约占20%~30%,而在排泄区快速流占比减少至2.5%~10.0%.岩溶含水系统地下水动力条件主要受岩溶发育程度等介质内部结构影响,济南泉域岩溶含水层岩溶发育程度较低,含水介质和水流通道以岩溶裂隙为主,地下水运动以基质流为主.   相似文献   

15.
The quantification of submarine and intertidal groundwater discharge (SiGD) or purely submarine groundwater discharge (SGD) from coastal karst aquifers presents a major challenge, as neither is directly measurable. In addition, the expected heterogeneity and intrinsic structure of such karst aquifers must be considered when quantifying SGD or SiGD. This study applies a set of methods for the coastal karst aquifer of Bell Harbour in western Ireland, using long-term onshore and offshore time series from a high-resolution monitoring network, to link catchment groundwater flow dynamics to groundwater discharge as SiGD. The SiGD is estimated using the “pollution flushing model”, i.e. a mass-balance approach, while catchment dynamics are quantified using borehole hydrograph analysis, single-borehole dilution tests, a water balance calculation, and cross-correlation analysis. The results of these analyses are then synthesised, describing a multi-level conduit-dominated coastal aquifer with a highly fluctuating overflow regime draining as SiGD, which is in part highly correlated with the overall piezometric level in the aquifer. This concept was simulated using a hydraulic pipe network model built in InfoWorks ICM [Integrated Catchment Modeling]® version 7.0 software (Innovyze). The model is capable of representing the overall highly variable discharge dynamics, predicting SiGD from the catchment to range from almost 0 to 4.3 m3/s. The study emphasises the need for long-term monitoring as the basis for any discharge studies of coastal karst aquifers. It further highlights the fact that multiple discharge locations may drain the aquifer, and therefore must be taken into consideration in the assessment of coastal karst aquifers.  相似文献   

16.
The Xiangxi River basin, South China, is a steep terrane with well-developed karst features and an important Cambrian-Ordovician aquifer. Meteoric water in this mountainous area features a mean δ18O elevation gradient of –2.4?‰/km. This gradient was used to estimate mean recharge elevations of 760 m for Shuimoxi (SMX) spring, 1,060 m for Xiangshuidong (XSD) spring, and 1,430 m for drill hole ZK03, indicating multiple flow paths in the Cambrian-Ordovician karst aquifer. Mean residence times of 230 and 320 days and ～2 years were estimated for these features, respectively, using the damped running average model that predicts the isotopic variations in groundwater from those in precipitation. Groundwater in the regional karst flow system has the longest residence time, the highest recharge elevation, the longest flow paths, the lowest addition of anthropogenic components, and the greatest amount of water–rock interaction as indicated by its higher dissolved solids, Mg2+ concentrations and Mg/Ca ratios than the springs. In contrast, the local and shallow karst flow systems respond rapidly to recharge events. Artificial tracer tests prove that these shallow karst systems can also quickly transmit anthropogenic contaminants, indicating that they are highly vulnerable to human impacts, which include the enrichment of NO3 –. The intensity of water–rock interaction and groundwater vulnerability are mainly determined by the structure and dynamics of the multiple karst flow systems.  相似文献   

17.
A series of long karst spring discharges have been analysed to determine trends, fluctuations and relationship to rainfall. Data come from aquifers in southern Italy, and in some cases cover more than one hundred years of records. Based on yearly discharge data, hydrological series show the drop of the discharge after 1986, which has been interrupted by the recent wet years of 2009 and 2010. This drop is connected to the decrease in annual rainfall, but other factors also seem to contribute to this phenomenon. Based on monthly scale data series, the relationship between meteorological and hydrological droughts has been analyzed, using the standard precipitation index (SPI). As karst systems are large reservoirs, only longer meteorological droughts induce groundwater droughts, and the start, duration and time-lag of the hydrological droughts have been evaluated.  相似文献   

18.
Several natural and anthropogenic tracers have been used to evaluate groundwater residence time within a karstic limestone aquifer in southeastern New Mexico, USA. Natural groundwater discharge occurs in the lower Pecos Valley from a region of karst springs, wetlands and sinkhole lakes at Bitter Lakes National Wildlife Refuge, on the northeast margin of the Roswell Artesian Basin. The springs and sinkholes are formed in gypsum bedrock that serves as a leaky confining unit for an artesian aquifer in the underlying San Andres limestone. Because wetlands on the Refuge provide habitat for threatened and endangered species, there is concern about the potential for contamination by anthropogenic activity in the aquifer recharge area. Estimates of the time required for groundwater to travel through the artesian aquifer vary widely because of uncertainties regarding karst conduit flow. A better understanding of groundwater residence time is required to make informed decisions about management of water resources and wildlife habitat at Bitter Lakes. Results indicate that the artesian aquifer contains a significant component of water recharged within the last 10–50 years, combined with pre-modern groundwater originating from deeper underlying aquifers, some of which may be indirectly sourced from the high Sacramento Mountains to the west.  相似文献   

19.
Discharge-area groundwater in Jinan, a typical karst region in northern China, was investigated by studying both the hydrological and chemical processes evolving from the recharge in mountainous terrains to the karst-spring outflows in the metropolitan area. Large-scale exploitation of karst groundwater has led to a disturbing trend in the ever-decreasing spring outflow rates and groundwater level. There is insufficient information about the Jinan karst aquifers, which provide the main water sources to meet human demand and to sustain spring outflow. The coupling of hydrological and chemical processes quantifies the flow system through aqueous chemistry characterization of the water sources. This approach is used to study the groundwater flow discharges in different locations and geological settings. The potentiometric data indicated limited vertical connectivity between distinct hydrogeological units and alteration of the recharge regime by the faults and by artificial exploitation. Shallow groundwater primarily belongs to the local flow system, with high nitrate concentration and enriched stable isotopic contents. Thermal groundwater has high concentrations of chloride and total dissolved solids, derived from a regional flow system with the highest recharge altitudes and long residence time. Non-thermal karst water may be attributed to the intermediate flow system, with uniform HCO3–Ca(Mg) facies and low nitrate concentration. This work highlighted discharge as a fingerprint of groundwater flow conditions and provides a better insight into the hydrogeological system.  相似文献   

20.
In the Apalachicola-Chattahoochee-Flint (ACF) river basin in Alabama, Georgia, and Florida (USA), population growth in the city of Atlanta and increased groundwater withdrawal for irrigation in southwest Georgia are greatly affecting the supply of freshwater to downstream regions. This study was conducted to understand and quantify the effect of irrigation pumpage on the karst Upper Floridan Aquifer and river–aquifer interactions in the lower ACF river basin in southwest Georgia. The groundwater MODular Finite-Element model (MODFE) was used for this study. The effect of two drought years, a moderate and a severe drought year, were simulated. Comparison of the results of the irrigated and non-irrigated scenarios showed that groundwater discharge to streams is a major outflow from the aquifer, and irrigation can cause as much as 10 % change in river–aquifer flux. The results also show that during months with high irrigation (e.g., June 2011), storage loss (34 %), the recharge and discharge from the upper semi-confining unit (30 %), and the river–aquifer flux (31 %) are the major water components contributing towards the impact of irrigation pumpage in the study area. A similar scenario plays out in many river basins throughout the world, especially in basins in which underlying karst aquifers are directly connected to a nearby stream. The study suggests that improved groundwater withdrawal strategies using climate forecasts needs to be developed in such a way that excessive withdrawals during droughts can be reduced to protect streams and river flows.  相似文献   

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