Hydrogeochemical characteristics of surface water and groundwater in the karst basin,southwest China   总被引：1，自引：0，他引：1  

Pan Wu  Changyuan Tang  Lijun Zhu  Congqiang Liu  Xuefang Cha  Xiuzhen Tao 《水文研究》2009,23(14):2012-2022

Groundwater is a very significant water source used for irrigation and drinking purposes in the karst region, and therefore understanding the hydrogeochemistry of karst water is extremely important. Surface water and groundwater were collected, and major chemical compositions and environmental isotopes in the water were measured in order to reveal the geochemical processes affecting water quality in the Gaoping karst basin, southwest China. Dominated by Ca²⁺, Mg²⁺, HCO₃^? and SO₄^2?, the groundwater is typically characterized by Ca? Mg? HCO₃ type in a shallow aquifer, and Ca? Mg? SO₄ type in a deeper aquifer. Dissolution of dolomite aquifer with gypsiferous rocks and dedolomitization in karst aquifers are important processes for chemical compositions of water in the study basin, and produce water with increased Mg²⁺, Ca²⁺ and SO₄^2? concentrations, and also increased TDS in surface water and groundwater. Mg²⁺/Ca²⁺ molar ratios in groundwater decrease slightly due to dedolomitization, while the mixing of discharge of groundwater with high Mg²⁺/Ca²⁺ ratios may be responsible for Mg²⁺/Ca²⁺ ratios obviously increasing in surface water, and Mg²⁺/Ca²⁺ ratios in both surface water and groundwater finally tending to a constant. In combination with environmental isotopic analyses, the major mechanism responsible for the water chemistry and its geochemical evolution in the study basin can be revealed as being mainly from the water–rock interaction in karst aquifers, the agricultural irrigation and its infiltration, the mixing of surface water and groundwater and the water movement along faults and joints in the karst basin. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

萍-乐坳陷带之岩溶发育规律及岩溶水富集特征     

张爱华 《火山地质与矿产》2010,(2):149-156

萍-乐坳陷带为江西省最主要的隐伏岩溶发育区带之一,岩溶地层发育,地表水、地下水循环交替强烈,地质构造复杂,为岩溶的发育、岩溶地下水的富集提供了良好的条件。查明岩溶发育规律及岩溶水的富集特征,可为地下水资源合理开发与地质环境保护提供科学依据。  相似文献   

Validation of a Numerical Indicator of Microbial Contamination for Karst Springs   总被引：1，自引：0，他引：1  

Christoph Butscher  Adrian Auckenthaler  Stefan Scheidler  Peter Huggenberger 《Ground water》2011,49(1):66-76

Rapid changes in spring water quality in karst areas due to rapid recharge of bacterially contaminated water are a major concern for drinking water suppliers and users. The main objective of this study was to use field experiments with fecal indicators to verify the vulnerability of a karst spring to pathogens, as determined by using a numerical modeling approach. The groundwater modeling was based on linear storage models that can be used to simulate karst water flow. The vulnerability of the karst groundwater is estimated using such models to calculate criteria that influence the likelihood of spring water being affected by microbial contamination. Specifically, the temporal variation in the vulnerability, depending on rainfall events and overall recharge conditions, can be assessed and quantified using the dynamic vulnerability index (DVI). DVI corresponds to the ratio of conduit to diffuse flow contributions to spring discharge. To evaluate model performance with respect to predicted vulnerability, samples from a spring were analyzed for Escherichia coli, enterococci, Clostridium perfringens, and heterotrophic plate count bacteria during and after several rainfall events. DVI was shown to be an indication of the risk of fecal contamination of spring water with sufficient accuracy to be used in drinking water management. We conclude that numerical models are a useful tool for evaluating the vulnerability of karst systems to pathogens under varying recharge conditions  相似文献   

Formation of phreatic caves in an eogenetic karst aquifer by CO2 enrichment at lower water tables and subsequent flooding by sea level rise     

J. D. Gulley  J. B. Martin  P. J. Moore  J. Murphy 《地球表面变化过程与地形》2013,38(11):1210-1224

Formation of extensive phreatic caves in eogenetic karst aquifers is widely believed to require mixing of fresh and saltwater. Extensive phreatic caves also occur, however, in eogenetic karst aquifers where fresh and saltwater do not mix, for example in the upper Floridan aquifer. These caves are thought to have formed in their modern settings by dissolution from sinking streams or by convergence of groundwater flow paths on springs. Alternatively, these caves have been hypothesized to have formed at lower water tables during sea level low‐stands. These hypotheses have not previously been tested against one another. Analyzing morphological data and water chemistry from caves in the Suwannee River Basin in north‐central Florida and water chemistry from wells in the central Florida carbonate platform indicates that phreatic caves within the Suwannee River Basin most likely formed at lower water tables during lower sea levels. Consideration of the hydrological and geochemical constraints posed by the upper Floridan aquifer leads to the conclusion that cave formation was most likely driven by dissolution of vadose CO₂ gas into the groundwater. Sea level rise and a wetter climate during the mid‐Holocene lifted the water table above the elevation of the caves and placed the caves tens of meters below the modern water table. When rising water tables reached the land surface, surface streams formed. Incision of surface streams breached the pre‐existing caves to form modern springs, which provide access to the phreatic caves. Phreatic caves in the Suwannee River Basin are thus relict and have no causal relationship with modern surficial drainage systems. Neither mixing dissolution nor sinking streams are necessary to form laterally extensive phreatic caves in eogenetic karst aquifers. Dissolution at water tables, potentially driven by vadose CO₂ gas, offers an underappreciated mechanism to form cavernous porosity in eogenetic carbonate rocks. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

The origin and the formation laws of groundwater and mine water chemistry in the Eastern Donets Basin     

A. I. Gavrishin  A. Coradini 《Water Resources》2009,36(5):538-547

Successive classification modeling of multivariate observations was used to objectively identify and quantitatively describe four major hydrogeochemical directions of changes in mine water chemistry and two hydrogeochemical trends for groundwater in the Eastern Donets Basin (two types of vertical hydrogeochemical zonality). Processes along the first hydrogeochemical direction result in the formation of acid sulfate mineralized water, those along the second direction form neutral chloride-sulfate waters, those along the third direction form sulfate-chloride and chloride, and those along the fourth direction form soda, hydrocarbonate-sulfate-chloride waters; the processes of sulfur oxidation and water mixing play the main role in the formation of water chemistry. In the case of groundwater, the first trend (direct zonality) manifests itself in the formation of highly mineralized chloride sodium water (mineralization of up to 60–80 g/l), while the second trend (inverse zonality) results in the formation of moderately mineralized soda hydrocarbonate-chloride and chloride sodium water (1–3 g/l). The genesis of water chemistry is explained with the engagement of infiltration, sedimentation, and evaporation-condensation hypotheses. Giving preference to the evaporation-condensation genesis of groundwater chemistry according to the second trend, the authors came to the conclusion that the Eastern Donets Basin is promising in terms of oil and gas accumulations.  相似文献   

Mass transport triggered by heavy rainfall: the role of endorheic basins and epikarst in a regional karst aquifer          下载免费PDF全文

Maria Dolores Fidelibus  Gabriella Balacco  Andrea Gioia  Vito Iacobellis  Giuseppe Spilotro 《水文研究》2017,31(2):394-408

This study aims at recognizing the mechanisms of mass transport between the karst surface and the saturated zone in a morphostructural relief of the Mesozoic karst carbonate platform of Murgia (Puglia, Southern Italy). The large dimension of the karst aquifer, the regional scale of the flow system, the boundary condition constituted by the sea, and the lack of freshwater springs constrain to the use of wells as monitoring points and limit the study area to the recharge area comprising 986 endorheic basins. The concentrations of non‐reactive tracers (nitrates) in the waters of autogenic recharge (from endorheic basins) have been modeled through the evaluation of effective infiltration, land use, and nitrogen surplus, with reference to a time window, which includes a low precipitation period followed by significant rainfall events. The comparison between the modeled nitrate concentrations and the nitrate concentrations measured in ground waters, coupled with the analysis of groundwater chemograms and records of hydraulic heads (all referred to the same time window), allows inferring the mechanism of mass transport between the karst surface and the groundwater table. The mass transport conceptual model requires the presence of the epikarst. The infiltration of significant rainfall in the endorheic basins after a low precipitation period displaces waters stored in the epikarst toward the saturated zone. Ground waters in the post‐event period show higher concentrations of nitrates, lower concentrations of total organic carbon, and higher Mg/Ca ratios than both those of the pre‐event period and the autumn‐winter recharge period. The post‐event recharge from epikarst storage determines a transient hazard of groundwater pollution with a time lag from the occurrence of the heavy rainfall.  相似文献   

An Application of HFE-D for Evaluating Sea Water Intrusion in Coastal Aquifers of Southern Vietnam     

Thi Thuy Van Le  Rungruang Lertsirivorakul  Tran Vuong Bui  Marcia K. Schulmeister 《Ground water》2020,58(6):1012-1022

The coastal aquifers and inland waters of the Long Xuyen Quadrangle and Ca Mau Peninsula of southern Vietnam have been significantly impacted by sea water intrusion (SI) as a result of recent anthropogenic activities. This study identified the evolution and spatial distribution of hydrochemical conditions in coastal aquifers at this region using Hydrochemical Facies Evolution Diagram (HFE-D) and Geographical Information System mapping. Hydraulic heads and water chemistry were measured at 31 observation wells in four layered aquifers during dry and rainy seasons in early (2005), and more recent (2016), stages of agricultural development. Hydrochemical facies associated with intrusion or freshening stages were mapped in each aquifer after assigning mixing index values to each facies. The position of groundwater freshening and SI phases differed in Holocene, Upper Pleistocene, Middle Pleistocene, and Lower Pleistocene aquifers. The geographic position of freshening and intrusion fronts differ in dry and rainy seasons, and shifted after 11 years of groundwater abstraction in all four aquifers. The spatial and temporal differences in hydrochemical facies distributions according to HFE-D reflect the relative impact of SI in the four aquifers. The study results provide a better understanding of the evolution of groundwater quality associated with SI in a peninsular coastal aquifer system, and highlight the need for improving groundwater quality and management in similar coastal regions.  相似文献   

Drying increases organic colloidal mobilization in the karst vadose zone: Evidence from a 15-year cave-monitoring study     

Jin Liao  Chaoyong Hu  Xiuli Li  Jiaoyang Ruan 《水文研究》2021,35(4):e14163

Understanding the hydrological processes of colloids within the karst vadose zone is vital to the security of karst groundwater and providing appropriate paleohydrological explanations of colloid-facilitated metals in speleothem. This study addresses the mobilization mechanisms driving colloidal organic matter (COM) transport in the karst vadose zone using a 15-year long monthly monitoring dataset from a cave drip point (HS4) in Heshang Cave, Qingjiang Valley, China. Variations in COM concentrations were reported as the fluorescence difference values of raw and filtered (<0.22 μm) samples at an excitation wavelength of 320 nm and emission wavelength of ~400 nm. A fluorescence humification index (HIX) lower than 0.8 and an autochthonous index (BIX) higher than 1.2 indicated that the origin of COM was mainly from the karst vadose zone, rather than the soil zone. The COM concentration varied from 0.001 to 0.038 Raman Unit (RU), with evident seasonal fluctuations. Rising limbs for COM values occurred prior to rising limbs within a dripwater hydrograph; moreover, the COM peak values corresponding to the beginning of the increasing hydrograph generally suggested that the mobilization of COM reflected the movement of the air–water interface (AWI) in the karst vadose zone rather than rainfall intensity or flow velocity. COM peak values were positively correlated with the antecedent drying duration and negatively correlated with HIX values. These phenomena may be explained by the increased amount of organic matter that was aggregated and absorbed on the surface of carbonate in the karst vadose zone during a longer drying duration. Moreover, the longer drying duration was also beneficial to autochthonous biological activity, which subsequently decreased the HIX value of the organic matter in the karst vadose zone. The movement of AWI and the drying duration are both controlled by the outside weather conditions. This study is therefore conducive to evaluating the security of karst groundwater in response to climate change, and challenges prevailing paleoclimate interpretations of colloid-facilitated metal abundance timeseries reported from speleothems.  相似文献   

Modeling Groundwater Depletion at Regional and Global Scales: Present State and Future Prospects     

Yoshihide Wada 《Surveys in Geophysics》2016,37(2):419-451

Except for frozen water in ice and glaciers, groundwater is the world’s largest distributed store of freshwater and has strategic importance to global food and water security. In this paper, the most recent advances quantifying groundwater depletion (GWD) are comprehensively reviewed. This paper critically evaluates the recently advanced modeling approaches estimating GWD at regional and global scales, and the evidence of feedbacks to the Earth system including sea-level rise associated with GWD. Finally, critical challenges and opportunities in the use of groundwater are identified for the adaption to growing food demand and uncertain climate.  相似文献   

Evaluation of the MODFLOW-2005 Conduit Flow Process   总被引：1，自引：0，他引：1  

Melissa E. Hill  Mark T. Stewart  Angel Martin 《Ground water》2010,48(4):549-559

The recent development of the Conduit Flow Process (CFP) by the U.S. Geological Survey (USGS) provides hydrogeologic modelers with a new tool that incorporates the non-Darcian, multiporosity components of flow characteristic of karst aquifers. CFP introduces new parameters extending beyond those of traditional Darcian groundwater flow codes. We characterize a karst aquifer to collect data useful for evaluating this new tool at a test site in west-central Florida, where the spatial distribution and cross-sectional area of the conduit network are available. Specifically, we characterize: (1) the potential for Darcian/non-Darcian flow using estimates of specific discharge vs. observed hydraulic gradients, and (2) the temporal variation for the direction and magnitude of fluid exchange between the matrix and conduit network during extreme hydrologic events. We evaluate the performance of CFP Mode 1 using a site-scale dual-porosity model and compare its performance with a comparable laminar equivalent continuum model (ECM) using MODFLOW-2005. Based on our preliminary analyses, hydraulic conductivity coupled with conduit wall conductance improved the match between observed and simulated discharges by 12% to 40% over turbulent flow alone (less than 1%).  相似文献   

A high‐altitude temporary spring in a compartmentalized carbonate aquifer: the role of low‐permeability faults and karst conduits     

Emma Petrella  Paolo Capuano  Massimiliano Carcione  Fulvio Celico 《水文研究》2009,23(23):3354-3364

The aim of this research was to refine the actual conceptual model related to the activation of high‐altitude temporary springs within the carbonate Apennines in southern Italy. The research was carried out through geophysical, hydrogeological, hydrochemical and isotopic investigations at the Acqua dei Faggi experimental site during five hydrologic years. The research demonstrated that, in carbonate aquifers where low‐permeability faults cause the aquifer system to be compartmentalized, high‐altitude temporary springs may be recharged by groundwater. In such settings, neither surface water infiltration in karst systems nor perched temporary aquifers play a role of utmost importance. The rare (once or a few time a year) activation of such springs is due to the fact that groundwater unusually reach the threshold head that allows the spring to flow. The activation of the studied high‐altitude temporary spring also depended on relationships between a low‐permeability fault core and a karst system that locally interrupts the low‐permeability barrier. In fact, when the hydraulic head did not reach the karst system, the concentrated head loss within the fault core did not allow the spring to flow, because the groundwater entirely flowed through the fault towards the downgradient compartment. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Effects of Changing Meteoric Precipitation Patterns on Groundwater Temperature in Karst Environments          下载免费PDF全文

A.E. Brookfield  G.L. Macpherson  M.D. Covington 《Ground water》2017,55(2):227-236

Climate predictions indicate that precipitation patterns will change and average air temperatures will increase across much of the planet. These changes will alter surface water and groundwater temperatures which can significantly affect the local and regional environment. Here, we examine the role of precipitation timing in changes to groundwater temperature in carbonate‐karst aquifers using measured groundwater level and temperature data from the Konza Prairie Long‐Term Ecological Research Site, Kansas. We demonstrate that shifts to increased cool‐season precipitation may mitigate the increases in groundwater temperature produced by increases in average annual air temperature. In karst, the solution‐enlarged conduits allow faster and focused recharge, and the recharge‐event temperature can strongly influence the groundwater temperature in the aquifer. Our field data and analysis show that predictions of future groundwater conditions in karst aquifers need to consider changes in precipitation patterns, in addition to changes to average annual air temperature.  相似文献   

广西岩溶区工程地质灾害及场地处理     

杨仕升  蒙雷  何声  梁齐立 《震灾防御技术》2015,10(4):884-891

为减小岩溶区地质灾害带来的损失,以广西岩溶区为例,分析了广西岩溶地质的分布特点,对广西岩溶区的工程地质灾害进行研究分类,对岩溶区工程场地处理方法进行研究,综述了地表封闭防渗法、地面下加固处理法、结构物跨越法三大方法的原理、实施效果和实用性。研究发现:由于降雨和地下岩石类别差异等因素,广西的岩溶分布类型具有强烈的地域特性,形成了三大岩溶地貌特征;产生岩溶区地质灾害最主要的诱因是地下水的变化,重要工程中定时定点监控地下水变化十分重要;广西的岩溶区溶洞和土洞塌陷主要是人为因素造成的。  相似文献   

Model Averaging Techniques for Quantifying Conceptual Model Uncertainty     

Abhishek Singh  Srikanta Mishra  Greg Ruskauff 《Ground water》2010,48(5):701-715

In recent years a growing understanding has emerged regarding the need to expand the modeling paradigm to include conceptual model uncertainty for groundwater models. Conceptual model uncertainty is typically addressed by formulating alternative model conceptualizations and assessing their relative likelihoods using statistical model averaging approaches. Several model averaging techniques and likelihood measures have been proposed in the recent literature for this purpose with two broad categories—Monte Carlo-based techniques such as Generalized Likelihood Uncertainty Estimation or GLUE (Beven and Binley 1992) and criterion-based techniques that use metrics such as the Bayesian and Kashyap Information Criteria (e.g., the Maximum Likelihood Bayesian Model Averaging or MLBMA approach proposed by Neuman 2003) and Akaike Information Criterion-based model averaging (AICMA) (Poeter and Anderson 2005). These different techniques can often lead to significantly different relative model weights and ranks because of differences in the underlying statistical assumptions about the nature of model uncertainty. This paper provides a comparative assessment of the four model averaging techniques (GLUE, MLBMA with KIC, MLBMA with BIC, and AIC-based model averaging) mentioned above for the purpose of quantifying the impacts of model uncertainty on groundwater model predictions. Pros and cons of each model averaging technique are examined from a practitioner's perspective using two groundwater modeling case studies. Recommendations are provided regarding the use of these techniques in groundwater modeling practice.  相似文献