Karst morphology and groundwater vulnerability of high alpine karst plateaus

High alpine karst plateaus are recharge areas for major drinking water resources in the Alps and many other regions. Well-established methods for the vulnerability mapping of groundwater to contamination have not been applied to such areas yet. The paper characterises this karst type and shows that two common vulnerability assessment methods (COP and PI) classify most of the areas with high vulnerability classes. In the test site on the Hochschwab plateau (Northern Calcareous Alps, Austria), overlying layers are mostly absent, not protective or even enhance point recharge, where they have aquiclude character. The COP method classifies 82% of the area as highly or extremely vulnerable. The resulting maps are reasonable, but do not differentiate vulnerabilities to the extent that the results can be used for protective measures. An extension for the upper end of the vulnerability scale is presented that allows identifying ultra vulnerable areas. The proposed enhancement of the conventional approach points out that infiltration conditions are of key importance for vulnerability. The method accounts for karst genetical and hydrologic processes using qualitative and quantitative properties of karst depressions and sinking streams including parameters calculated from digital elevations models. The method is tested on the Hochschwab plateau where 1.7% of the area is delineated as ultra vulnerable. This differentiation could not be reached by the COP and PI methods. The resulting vulnerability map highlights spots of maximum vulnerability and the combination with a hazard map enables protective measures for a manageable area and number of sites.     

Environmental tracers as indicators of karst conduits in groundwater in South Dakota,USA

Environmental tracers sampled from the carbonate Madison aquifer on the eastern flank of the Black Hills, South Dakota, USA indicated the approximate locations of four major karst conduits. Contamination issues are a major concern because these conduits are characterized by direct connections to sinking streams, high groundwater velocities, and proximity to public water supplies. Objectives of the study were to estimate approximate conduit locations and assess possible anthropogenic influences associated with conduits. Anomalies of young groundwater based on chlorofluorocarbons (CFCs), tritium, and electrical conductivity (EC) indicated fast moving, focused flow and thus the likely presence of conduits. δ¹⁸O was useful for determining sources of recharge for each conduit, and nitrate was a useful tracer for assessing flow paths for anthropogenic influences. Two of the four conduits terminate at or near a large spring complex. CFC apparent ages ranged from 15 years near conduits to >50 years in other areas. Nitrate-N concentrations >0.4 mg/L in groundwater were associated with each of the four conduits compared with concentrations ranging from <0.1 to 0.4 mg/L in other areas. These higher nitrate-N concentrations probably do not result from sinking streams but rather from other areas of infiltration.     

Behaviour of metals and nutrients in soils and groundwater of a karst polje

The Croatian south part of the country is mainly composed of strongly krastified carbonate rocks. Also in this south part of Croatia is lacking of large depressions and poljes with thick covers. Some karst poljes and depressions may have thick covers, like for example the Vransko polje. The Vransko polje is characterised by an intensive agricultural activity. At the centre of the polje is located a karst spring (Turanjsko jezero), which is used for the water supply of the town Biograd and its surroundings. Total metals, nutrients (nitrate, ammonia, phosphate), organic matter content and cation exchange capacity (CEC) were measured in soil samples collected from the polje. Metals and nutrients were also measured in the water samples of channel Kotarka (which is passing through the area) and three springs (Turanjsko jezero, Kakma and Tinj). Measured total concentrations of metals of soil samples were treated by R-cluster multivariate statistical analysis. The result of statistical analysis showed grouping of metals with similar behaviour. Content of metals and nutrients were low in the spring samples but high in the water sample of the channel Kotarka, because the channel drains the water from the surroundings. Although agricultural activity in the Vransko polje is high, there is no high anthropogenic influence on groundwater and soil. They are both of good quality.     

双峰、界岭幅岩溶地下水开发利用与区划研究

双峰、界岭幅位于湖南省中部邵阳凹陷盆地,地处西南岩溶丘陵区,总面积913 km^2,所涉行政区有:邵阳的新邵县、邵东县和娄底的双峰县、涟源市,特殊的地貌地质形态造就了湖南省著名的"衡邵干旱走廊"。根据调查统计,区内干旱面积64. 71 km^2,总缺水人口38 500人,占区内人口总数的11. 46%。本文意在探索区内的合理、高效、科学的地下水开发利用方式,提出了5种地下水开发利用区划方案,为区内解决干旱缺水困难问题提供理论依据。     

Identification of sources of chemical constituents in groundwater from the Vilnius wellfields, Lithuania

The only source of drinking water in Vilnius City, Lithuania's capital, is groundwater. It can be supplied from 20 wellfields situated in the City or its environs. About half of them (11) are located in the valley of the Neris River crossing the City. The exploited aquifers were formed by melting continental glaciers and modified by the river. Until 1990 groundwater resources had not been conserved—the per capita consumption for domestic use in Vilnius reached 350 l/day. After 1990, due to the increasing cost of supplying drinking water, its consumption was reduced by a factor of three. As pumping rates of wellfields in Vilnius were increased or decreased, the groundwater quality was changed significantly. It is mainly affected by the surface water and shallow aquifers of the hydrologic system. The unoxidised organic matter that enters the exploitable aquifers from rivers and polluted shallow groundwater consumes scarce oxygen resources, thus creating anoxic conditions favourable for increasing the accumulation of iron, manganese and ammonium. Modelling and monitoring data show that the concentrations of sulphates and chlorides in Vilnius wellfields indicate not only the rise of brackish water from below, but also downward seepage of polluted surface water into the aquifers.     

Travel time based approach for the assessment of vulnerability of karst groundwater: the Transit Time Method

Karst aquifers represent important water resources in many parts of the world. Unfortunately, karst aquifers are characterised by high contamination risks. This paper presents a travel time based method for the estimation of karst groundwater vulnerability. It considers (1) physics-based lateral flow within the uppermost weathered zone (epikarst) in a limestone-dominated region and (2) high velocities of vertical infiltration at discrete infiltration points (e.g. sinkholes) or lines (e.g. dry valleys, faults). Consequently, the Transit Time Method honours the actual flow path within the unsaturated zone of a karst aquifer system. A test site in Northern Jordan was chosen for the demonstration of the assessment technique, i.e. the catchment area of the Qunayyah Spring north of the capital Amman. The results demonstrate that zones of highest vulnerability lie within valleys and nearby main fault zones. It also reveals that regions, categorised as protected areas by other methods due to thick unsaturated zones, contribute to a major degree to the total risk.     

Effects of urbanization on groundwater level in aquifers of Binh Duong Province,Vietnam

The purpose of this paper was to assess the impact of urbanization on the groundwater level(GWL)in aquifers of Binh Duong(BD)Province.The research method is to analyze the trend of GWL,the recharge capacity of surface over time and the relationship between them.The data of the GWL used in the study are the average values in the dry and rainy seasons of 35 observation wells from 2011 to 2018,which are in Pleistocene and Pliocene aquifers.The ability to recharge groundwater from the surface in this study was represented by the curve number(CN),a parameter used in hydrology for calculating direct runoff or infiltration from rainfall.The land use data to identify the CN was analyzed from the Landsat images.The results show that besides over-exploitation,the change of surface characteristic due to the urbanization development process is also the cause of the GWL decline.The analysis of seasonal GWL data shows that the increase in impervious surface area is the cause of GWL decline in the Pleistocene aquifer,which is more evident in the rainy season than in the dry season.The statistical results also show that in the rainy season and in shallow aquifers,a higher CN change can be found with the wells that had a remarkable GWL decline compared to the remaining wells.     

地下水水位管理研究进展综述

地下水位变化是地下水资源量多寡最直接的表现形式,是地下水管理最重要的控制性指标。对地下水水位进行管理,可实现对地下水资源的量化管理。通过对地下水位与生态及地质环境的关系、地下水位阈值、地下水管理水位划定等几个方面进行综述,力图从相对全面的角度认识当前地下水水位管理的发展。在回顾地下水水位管理以上研究进展的基础上,对我国地下水水位管理面临的问题、地下水管理策略、复合型地区地下水水位管理等发展趋势进行了探讨,为相关研究人员提供一定的参考。     

论岩溶地下水位对岩溶塌陷形成的控制作用——以山东枣庄市岩溶地面塌陷区为例

枣庄市是山东省岩溶地面塌陷的主要发育地区之一,岩溶地面塌陷灾害连年发生,给当地的生产、生活造成巨大经济损失,已成为该地区经济发展的制约因素。本文对该地区的地质条件、塌陷现状及岩溶地面塌陷的分布规律进行了分析归纳,从中得出枣庄岩溶地面塌陷容易发生在:在第四系厚度为5～10m的地段,时间为每年4～9月份,地势低洼处。本文从压力差的角度,在简要分析岩溶管道的发育程度、盖层条件的基础上,分析了地下水位在枣庄地面岩溶塌陷的控制作用,并以此为依据简要提出了几个防治建议。     

Effects of groundwater level on vegetation in the arid area of western China

At present, investigation about the relationship between the change of groundwater level and vegetation mostly focuses on specific watersheds, i.e. limited in river catchment scale. Understanding the change of groundwater level on vegetation in the basin or large scale, be urgently needed. To fill this gap, two typical arid areas in the west of China (Tarim Basin and Qaidam Basin) were chosen the a typical research area. The vegetation status was evaluated via normalization difference vegetation index (NDVI) from 2000 to 2016, sourced from MODN1F dataset. The data used to reflect climate change were download from CMDSC (http://data.cma.cn). Groundwater level data was collected from monitor wells. Then, the relationship of vegetation and climate change was established with univariate linear regression and correlation analysis approach. Results show that: Generally, NDVI value in the study area decreased before 2004 then increased in the research period. Severe degradation was observed in the center of the basin. The area with an NDVI value > 0.5 decreased from 12% to 6% between 2000 and 2004. From 2004 to 2014, the vegetation in the study area was gradually restored. The whole coverage of Qaidam Basin was low. And the NDVI around East Taigener salt-lake degraded significantly, from 0.596 to 0.005, 2014 and 2016, respectively. The fluctuation of groundwater level is the main reason for the change of surface vegetation coverage during the vegetation degradation in the basin. However, the average annual precipitation in the study area is low, which is not enough to have a significant impact on vegetation growth. The annual average precipitation showed an increase trend during the vegetation restoration in the basin, which alleviates the water shortage of vegetation growth in the region. Meanwhile, the dependence of surface vegetation on groundwater is obviously weakened with the correlation index is –0.248. The research results are of some significance to eco-environment protection in the arid area of western China.© 2021 China Geology Editorial Office.     

Investigation of groundwater flow in karst areas using component separation of natural potential measurements

 The natural (electrical) potential (NP) method – also known as self-potential, spontaneous potential and streaming potential (SP) – has been used to locate areas of groundwater flow in karst terrane. NP is the naturally occurring voltage at the ground surface resulting from ambient electrical currents within the earth. The measurement of NP can be used to characterize groundwater flow in karst terrane because electrical potential gradients are generated by the horizontal flow of water along fractures or conduits and the vertical infiltration of water into fractures or shafts. NP data from a site on the Mitchell Plain of southern Indiana, USA, revealed that NP data can be decomposed into three components: topographic effect, residual NP and noise. At this site, NP was inversely proportional to elevation, but the correlation varied with time. The topographic correction factor varied from –2.5 to –1.2 mV/m (NP change per unit elevation increase), with an average linear correlation coefficient (R) of 0.95. Because the site slopes toward an adjacent creek that is the local groundwater discharge zone, one possible explanation for this effect is a streaming-potential mechanism generated by groundwater movement toward the creek. The residual NP data revealed three negative anomalies at the survey area. Two of them coincide with sinkholes. A part of the third anomaly is coincident with a small valley, and concentrated infiltration does occur at this elevation in other valleys at the site, as evidenced by the existence of sinkholes. However, the dispersed, low-magnitude nature of the third anomaly does not prove the existence of concentrated groundwater recharge activity. Received: 18 March 1998 · Accepted: 27 April 1998     

Effect of geochemical conditions on fate of organic compounds in groundwater

In situ microcosms were successfully used to study the degradation of a range of organic compounds in two pristine aquifers, one aerobic (Vejen) and one anaerobic (Villa Farm). Degradation and sorption behavior in the laboratory column microcosms packed with Villa Farm sediment was very similar to that in the in situ microcosms. However, when the columns were packed with quartz and equilibrated with aerated Villa Farm groundwater, behavior mirrored that at Vejen, indicating that oxygen rather than sediment or groundwater composition was the critical parameter. The aromatic and polyaromatic compounds (benzene, toluene,o-xylene, naphthalene) degraded under aerobic conditions only. The organochlorine compounds (trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, 1,4-dichlorobenzene and 1,2-dichlorobenzene) showed little or no sign of degradation either aerobically or anaerobically. Interpretation of the data was complicated by strong sorption to the Villa Farm sediment but tetrachloromethane, nitrobenzene, ando-nitrophenol appeared to degrade under anaerobic conditions only. Phenol degraded rapidly under both sets of conditions.     

Dynamics and contribution of karst groundwater to surface flow during Mediterranean flood

This paper describes the role of groundwater contribution to surface flow at the Causse d’Aumelas, a karst system near Montpellier (France), which is traversed by an intermittent river, the Coulazou. A first hydrologic model integrating a digital terrain model shows the inability of a standard rainfall-runoff model to replicate recorded flood hydrographs. While the flood peaks are routed through the karstic system along the Coulazou without a phase lag, the peak magnitude is somewhat modified. These results indicate an initial karst system recharge followed by a significant contribution to surface flow. A hydrodynamic analysis of ground-water flow confirms these results: the karst system first absorbs part of the rainfall, which induces a general water table rise within the aquifer, and then contributes to surface flow in the Coulazou.     

Assessment of water level threshold for groundwater restoration and over-exploitation remediation the Beijing-Tianjin-Hebei Plain

The Beijing-Tianjin-Hebei Plain (BTHP) is the political, economic and cultural center of China, where groundwater is the main source of water supply to support social and economic development. Continuous overdraft of the resources has caused a persistent decline of groundwater level and formed a huge cone of depression at a regional scale. This paper addresses current groundwater situation over the BTHP area. The paper also delineates the groundwater flow field, using groundwater level data, in order to provide an effective method for the restoration of groundwater level and associated water resources management. Based on the analysis of multiple factors, such as groundwater level, soil salinization, ground subsidence, groundwater recharge and storage, urban underground space security, formation of fractures, and seawater intrusion, the threshold for groundwater level restoration is defined, and some measures for groundwater over-exploitation management are accordingly proposed. The study shows that: (i) Since the 1980s to 2020, shallow groundwater level in the western part of the BTHP area has dropped by 25 m to 60 m, while the cumulative decline of deep groundwater in the central and eastern regions is in the range of 40–80 m; (ii) The water table of the shallow groundwater within the depression zone over the Western Piedmont Plain should be controlled in the range of 15–30 m below ground level (mbgl), while the depth of groundwater level in large and medium-sized urban areas should be controlled within 20–30 mbgl. The groundwater level in the resource preservation area should be controlled within 10–15 mbgl, and the groundwater level in the area with identified soil salinization in the central and eastern plain should be controlled within 3–10 mbgl. However, for the deep groundwater in the central and eastern plainwater, the main focus of the resources management is to control the land subsidence. The water level in the severe land subsidence area should be controlled within 45–60 mbgl, and in the general subsidence area should be controlled within 30–45 mbgl; (iii) Based on the water level recovery threshold and proposed groundwater overdraft management program, if the balance of abstraction and recharge is reached in 2025, the shallow groundwater abstraction needs to be gradually reduced by about 2×10⁸ m³. Meanwhile, the ecological water replenishment of rivers through the South-to-North Water Transfer Project should be increased to 28.58×10⁸ m³/a, and the deep groundwater abstraction needs to be gradually reduced by 2.24×10⁸ m³. To reach the target of shallow groundwater level in 2040, surface water replacement is recommended with a rate of 25.77×10⁸ m³/a and the ecological water replenishment of rivers in the South-to-North Water Diversion Project should reach 33.51×10⁸ m³/a. For deep groundwater recovery, it is recommended to replace the deep freshwater extraction with the utilization of shallow salt water by 2.82×10⁸ m³ , in addition to the amount of 7.86×10⁸ m³ by water diversion. The results are of great significance to the remediation of groundwater over-exploitation, the regulation of water resources development and utilization, and ecological protection in Beijing-Tianjin-Hebei plain.     

Impact of land use change on groundwater quality in a typical karst watershed of southwest China: a case study of the Xiaojiang watershed,Yunnan Province

The impact of land-use change on the quality of groundwater in the Xiaotjiang watershed, China was assessed for the period 1982–2004. Groundwater samples were collected from 30 monitoring points across the watershed, and were representative of the various changes, determined by remote sensing and geographical information systems. The results indicate that 610 km² (60% of the total watershed area) were subject to land-use change during the period. The most important changes were the conversion of 135 km² of forested land to cultivated land, and 211 km² of unused land to cultivated land. The main impact was ascribed to diffuse pollution from fertilizers applied to newly cultivated land, and from building development. Overall the groundwater pH value was significantly increased, as were the concentrations of ions , , , , and Cl⁻ in groundwater whilst the concentrations of Ca²⁺ and declined. More precisely, in the regions where forested land and unused land were converted into cultivated land, the pH value and the concentrations of Mg²⁺, , , , , Cl⁻ increased whilst the concentrations of Ca²⁺ and declined. However in the region where cultivated land was converted into construction land, the pH value and the concentrations of Ca²⁺, Mg²⁺, , , , , , Cl⁻ increased.

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Résumé  L’impact des changements de l’utilisation du territoire sur la qualité de l’eau souterraine dans le bassin versant de Xiaojiang, en Chine, a été évalué de 1982 à 2004. Des échantillons d’eau souterraine ont été récoltés à partir de 30 points d’observation éparpillés sur le bassin, représentant les divers changements déterminés par télédétection et système d’information géographique. Les résultats indiquent que 610 km² (soit 60% de la surface du bassin) ont été sujets à des modifications de l’utilisation du territoire sur cette période. Les changements les plus importants furent la conversion de 135 km² de forêt et 211 km² de terres inutilisées en terres cultivées. Le principal impact est attribué à la pollution diffuse des engrais utilisés en agriculture et pour les batiments. De manière générale le pH de l’eau souterraine a augmenté significativement, ainsi que les concentrations des ions , , , , et Cl⁻, tandis que les concentration en Ca²⁺ et ont diminué. Plus précisément dans les régions transformées en terres cultivées, la valeur du pH et les concentrations en Mg²⁺, , , , , Cl⁻ ont augmenté tandis que les concentrations en Ca²⁺ et ont diminué. Toutefois dans les régions cultivées converties en zones de construction, le pH et les concentrations en Ca²⁺, Mg²⁺, , , , , , Cl⁻ ont augmenté.

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Resumen  El impacto del cambio en uso de la tierra en la calidad del agua en la cuenca Xiaojiang, China fue evaluado para el periodo 1982–2004. Muestras de agua subterránea fueron tomadas de 30 puntos de monitoreo a través de la cuenca, y fueron representativas de los múltiples cambios, determinados por sensores remotos y sistemas de información geográfica. Los resultados indican que 610 km² (60% del área total de la cuenca) estaban sujetos a cambios de uso de la tierra durante el periodo estudiado. Los cambios más importantes fueron la conversión de 135 km² de bosques a tierra cultivada, y 211 km² de tierra sin uso (ociosa) a tierra cultivada. El impacto principal fue causado por contaminación difusa de fertilizantes aplicados a la tierra recientemente cultivada, y a desarrollo de construcciones. En general el pH en agua subterránea creció significantemente, al igual que las concentraciones de los iones , , , , y Cl⁻ en agua subterránea mientras que las concentraciones de Ca²⁺ y decrecieron. Mas precisamente, en las regiones donde bosque y tierra ociosa fueron convertidas en tierra cultivada, el valor de pH y las concentraciones de Mg²⁺, , , , , Cl⁻ crecieron mientras las concentraciones de Ca²⁺ y decrecieron. Sin embargo en la región donde tierra cultivada fue convertida en construcciones, el valor de pH y las concentraciones de Ca²⁺, Mg²⁺, , , , , , Cl⁻ crecieron.

     

Temporal variability of phosphorus fractions in Irish karst springs

Transfer pathways of phosphorus (P) from soil to surface waters are the subject of much current research because of concerns about eutrophication. However, P transfer via groundwater discharge has received little attention. Temporal P changes at eight Carboniferous limestone karst springs from two catchments in western Ireland are examined. The eight springs were sampled fortnightly between June and October 1999 and thereafter monthly until February 2000. Each sample was analysed for total P (TP), total dissolved P (TDP) and dissolved reactive P (DRP). Total P exhibited some hydrological response at all springs (e.g. increase from 45 to 107 µg l^–1) reflecting significant changes in particulate P (PP) (e.g. increase from 7 to 44 µg l^–1) and dissolved organic P (DOP) (e.g. increase from 0 to 27 µg l^–1), with DRP displaying greatest temporal stability. Greatest response to rainfall events occurred after the first major autumnal rains in September 1999, when there appeared to be dislodging of loosely bound PP and DOP, which was transported to groundwater. This response to the first autumnal rains probably reflects the hydrological switch where the catchments change from a soil moisture deficit to a soil moisture surplus situation. Daily autosampling demonstrated TP concentrations of up to 1,814 µg l^–1 due to local pollution, highlighting the need to adopt storm event driven sampling rather than discrete sampling in karstic springs. Identification and management of springs in karst areas, with associated point recharge via swallow holes, presents an urgent and demanding challenge.     

Determining safe yield and mapping water level zoning in groundwater resources of the Neishabour Plain

Groundwater is a crucial sources of water supply, especially in arid and semi-arid areas around the world. With uncontrolled withdrawals and limited availability of these resources, it is essential to determine the safe yield of these valuable resources. The Hill method approach was used in this study to determine the safe yield the Neishabour aquifer in Khorasan Razvi province in Iran. The results showed that the safe yield in the Neishabour aquifer is 60% lower than the current pumping amounts...     

Forecasting of groundwater level in hard rock region using artificial neural network

In hardrock terrain where seasonal streams are not perennial source of freshwater, increase in ground water exploitation has already resulted here in declining ground water levels and deteriorating its’ quality. The aquifer system has shown signs of depletion and quality contamination. Thus, to secure water for the future, water resource estimation and management has urgently become the need of the hour. In order to manage groundwater resources, it is vital to have a tool to predict the aquifer response for a given stress (abstraction and recharge). Artificial neural network (ANN) has surfaced as a proven and potential methodology to forecast the groundwater levels. In this paper, Feed-Forward Network based ANN model is used as a method to predict the groundwater levels. The models are trained with the inputs collected from field and then used as prediction tool for various scenarios of stress on aquifer. Such predictions help in developing better strategies for sustainable development of groundwater resources.     

乌鲁木齐河流域地下水水位监测网设计

文章阐述了乌鲁木齐河流域区域地下水水位监测网的优化设计。基于ARCGIS技术,运用水文地质学方法在叠加合成地下水动态类型分区图的基础上优化设计了区域地下水水位监测网密度;采用时间序列分析方法确定了地下水水位监测频率。首期施工安装了11个新的长期专门监测孔;对73个现有监测孔进行了维修并安装了孔口保护装置,安装了28套水位自动监测仪,初步实现了地下水水位的自动监测。     

Development of a 3D GIS and its application to karst areas

There is a growing interest in modeling and analyzing karst phenomena in three dimensions. This paper integrates geology, groundwater hydrology, geographic information system (GIS), database management system (DBMS), visualization and data mining to study karst features in Huaibei, China. The 3D geo-objects retrieved from the karst area are analyzed and mapped into different abstract levels. The spatial relationships among the objects are constructed by a dual-linker. The shapes of the 3D objects and the topological models with attributes are stored and maintained in the DBMS. Spatial analysis was then used to integrate the data in the DBMS and the 3D model to form a virtual reality (VR) to provide analytical functions such as distribution analysis, correlation query, and probability assessment. The research successfully implements 3D modeling and analyses in the karst area, and meanwhile provides an efficient tool for government policy-makers to set out restrictions on water resource development in the area.