The influence of karst features on environmental studies in Turkey

 The carbonate rocks of Turkey, which underlie about one third of the country, possess major water resources with great potential for electricity generation and water supplies. The ongoing development of karst features, especially in the southern part of Turkey, demonstrates specific environmental problems that occur in many karst water supply projects. Karst aquifers, springs, sinkholes, dolines, poljes and other karst features are of great importance from the standpoint of karst water resources and environmental research studies. In karst regions, conservation and protection of groundwater resources for both qualitative and quantitative evaluations is possible only when the catchment area is determined accurately. Since the catchment area in karst terrains is not limited by the surface drainage boundaries and the groundwater flows through well-developed coduits or fissures, the equations used in non-karstic areas cannot be applied to such karstic regions. Studies on the development of karst features and its environmental impacts in Turkey are of recent origin. Therefore, many unreliable methods are being applied in karstic areas. For example, the use of "shallow holes or sinkholes and fault zones" for septic water waste disposal or as sewage by those who are not familiar with karst, sometimes causes very serious problems of extensive groundwater pollution. This paper discusses the development of different karstic features in Turkey and case studies on its environmental impacts. Received: 27 December 1995 · Accepted: 10 July 1996     

Karst rivers’ particularity: an example from Dinaric karst (Croatia/Bosnia and Herzegovina)

The very complex system of sinking, losing and underground transboundary Karst rivers, lakes and aquifers in the central part of the deep and bare Dinaric karst in Croatia and Bosnia and Herzegovina is analysed. The groundwater and surface water are hydraulically connected through numerous karst forms which facilitate the exchange of water between the surface and subsurface. A complex underground conduit system is an inherent characteristic karst system analysed. Groundwater and surface water exchange with both adjacent and distant aquifers through underground routes or inflows from surface streams and artificial reservoirs. Because of a complex surface and underground karst features, which strongly influenced its hydrological and hydrogeological regime, the main open stream flow, with a longitude of about 106 km, undergoes eight name changes. In this paper, it is noted as “the eight-name river”. In fact, it represents one river with losing, sinking and underground stream sections. Different surface and underground karst forms play crucial roles in the way the water flowing over the surface and on the underground sections of its catchment. The analysed area is full of varied and often spectacular surface landforms, including for example the Blue and Red Lakes and the Kravice Waterfall. The analyses made in the paper show the existence of a decreasing trend of mean annual discharges on the eight-name river, which can cause numerous problems in the regional water resource management of this transboundary river and catchment.     

The vulnerability of karst springs—a case study of the Hubelj spring (SW Slovenia)

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.     

PaPRIKa: a method for estimating karst resource and source vulnerability��application to the Ouysse karst system (southwest France)

The intrinsic vulnerability mapping method, PaPRIKa, is proposed as a common basis for karst groundwater protection in France. PaPRIKa is a specialized method for studying karst aquifers, derived from updating the RISKE and EPIK methods. Both the structure and functioning of karst aquifers are considered in order to develop a resource and source-vulnerability mapping method. PaPRIKa means Protection of aquifers from the assessment of four criteria: P for protection (considering the most protective aspects among parameters related to soil cover, unsaturated zone and epikarst behavior), R for rock type, I for infiltration and Ka for karstification degree. The Ouysse karst system, located in the Causses area in southwest France, is one of the nine pilot sites where this method was tested and standardized. The specificities of the Ouysse system such as the size of the catchment area, the spatial variability of the karst network development, the thick infiltration zone and the system??s dual character (both karst and non-karst areas), have provided a valuable field of application. The vulnerability of the resource was assessed for the entire catchment area, while source-orientated cartography was attempted for the catchment areas of the three different capture works used for drinking water.     

Water vulnerability assessment in karst environments: a new method of defining protection areas using a multi-attribute approach and GIS tools (EPIK method)

 Groundwater resources from karst aquifers play a major role in the water supply in karst areas in the world, such as in Switzerland. Defining groundwater protection zones in karst environment is frequently not founded on a solid hydrogeological basis. Protection zones are often inadequate and as a result they may be ineffective. In order to improve this situation, the Federal Office for Environment, Forests and Landscape with the Swiss National Hydrological and Geological Survey contracted the Centre of Hydrogeology of the Neuchatel University to develop a new groundwater protection-zones strategy in karst environment. This approach is based on the vulnerability mapping of the catchment areas of water supplies provided by springs or boreholes. Vulnerability is here defined as the intrinsic geological and hydrogeological characteristics which determine the sensitivity of groundwater to contamination by human activities. The EPIK method is a multi-attribute method for vulnerability mapping which takes into consideration the specific hydrogeological behaviour of karst aquifers. EPIK is based on a conceptual model of karst hydrological systems, which suggests considering four karst aquifer attributes: (1) Epikarst, (2) Protective cover, (3) Infiltration conditions and (4) Karst network development. Each of these four attributes is subdivided into classes which are mapped over the whole water catchment. The attributes and their classes are then weighted. Attribute maps are overlain in order to obtain a final vulnerability map. From the vulnerability map, the groundwater protection zones are defined precisely. This method was applied at several sites in Switzerland where agriculture contamination problems have frequently occurred. These applications resulted in recommend new boundaries for the karst water supplies protection-zones. Received: 27 October 1997 · Accepted: 4 July 1998     

Karst groundwater management by defining protection zones based on regional geological structures and groundwater flow fields

In a semiarid region, the karst aquifer generally forms a large groundwater reservoir that can play an important role in regional water supply. But because of the specific physical properties of karst aquifers, they are vulnerable to pollution and anthropogenic impacts. Karst groundwater management strategies are vital. As representative of karst springs in a semiarid area, Niangziguan Springs is located in the east of Shanxi Province, China with an annual average rate of discharge of 10.34 m³/s (1956–2003) (Y. Liang, unpublished data). The Niangziguan Spring Basin covers an area of 7,394 km² with an annual average precipitation of 535 mm (1958–2003) (Hao et al. in Carsologica Sinica 23(1):43–47, 2004). Over the past three decades, accelerated groundwater exploitation has caused water-table decline in the aquifer, reduction of the spring discharge, and deterioration of water quality. In this study, three protection zones were defined to ensure the quality and capacity of this resource. The confluence of the 11 spring systems and the discharge areas were defined as I protection zone, the recharge basin was II protection zone, and the slack water area where there is little surface recharge was the III protection zone. Management strategies for each zone were suggested and evaluated to provide a scientific foundation for sustainable utilization.     

Submarine and intertidal groundwater discharge through a complex multi-level karst conduit aquifer

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.     

Characterization of the hydrogeology of the sacred Gihon Spring, Jerusalem: a deteriorating urban karst spring

The Gihon Spring, Jerusalem, is important for the major monotheistic religions. Its hydrogeology and hydrochemistry is studied here in order to understand urbanization effects on karst groundwater resources, and promote better water management. High-resolution monitoring of the spring discharge, temperature and electrical conductivity, was performed, together with chemical and bacterial analysis. All these demonstrate a rapid response of the spring to rainfall events and human impact. A complex karst system is inferred, including conduit flow, fissure flow and diffuse flow. Electrical conductivity, Na⁺ and K⁺ values (2.0 mS/cm, 130 and 50 mg/l respectively) are very high compared to other nearby springs located at the town margins (0.6 mS/cm, 15 and <1 mg/l respectively), indicating considerable urban pollution in the Gihon area. The previously cited pulsating nature of the spring was not detected during the present high-resolution monitoring. This phenomenon may have ceased due to additional water sources from urban leakage and irrigation feeding the spring. The urbanization of the recharge catchment thus affects the spring water dramatically, both chemically and hydrologically. Appropriate measures should therefore be undertaken to protect the Gihon Spring and other karst aquifers threatened by rapid urbanization.     

Influence of construction on hydrogeological and environmental conditions in the karst region,eastern Herzegovina,Yugoslavia

The region of eastern Herzegovina and Dubrovnik coastal belt is one of the hydrogeologically and hydrologically most interesting regions of Yugoslavia karst. The main water course in the region is the Trebinjica river, the largest sinking river in Europe. All the poljes in the catchment area are temporary flooded, hydrologically separated, and closed karst entities. Enormous quantities of available water are not evenly disturbed neither in the time nor in the space. The Trebinjica Hydrosystem project uses the basic concept of total water regime organization and its multipurpose utilization. With the construction of seven dams, six artificial reservoirs, six tunnels (with total length, 57 km), and four canals (with total length 74 km) the natural regime of surface and underground waters has been completely changed.As a consequence of water regime disturbance, a lot of changes have been observed in the catchment area: changes in the karst aquifers; local changes of climate conditions; eolic erosion effect; influence on the karst underground and littoral belt; influence on the springs yield; influence on adjacent catchment area; pollution of karst aquifers and influence of storage reservoirs on seismicity—induced seismicity. This article presents influences observed after the first stage of hydrosystem construction.     

Hydrological modeling in the karst area,Rižana spring catchment,Slovenia

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.     

Geochemical and stable isotopic variability within two rivers rising under the same mountain,but belonging to two distant watersheds

Complementary geochemical and stable isotope investigations of the Gorski Kotar karst aquifer system in western Croatia were obtained for the first time, to answer the question whether both studied rivers drain the same aquifer system or not. The two main rivers, the Kupa and the Rje?ina, rise under the same mountain range, but belong to two different watersheds (Black Sea and Adriatic Sea). The karst aquifer of Gorski Kotar is a potentially important source of drinking water for two neighboring countries, Croatia and Slovenia (Central and South Europe), and is strongly influenced by both Mediterranean and continental weather conditions. It is a part of the Dinaric karst, which is “locus typicus” for karst worldwide and one of the most typical karst areas in the world.     

Protection of karst aquifers in the Dinarides in Croatia

 This paper presents karst water protection measures being introduced in the Dinarides of Croatia. The spring sites for the water supply of the town of Rijeka, for its 200 000 inhabitants and the largest harbor of the northeastern side of the Adriatic Sea, have been used as a pilot research area. The European research project was used, and protection of water was generally divided into three phases. A categorization of springs has been made, and five basic protection zones have been distinguished. The rules of behavior in protected zones have been outlined. For the first time, the term water-supply "reserve" has been introduced, referring to the parts of the mountainous region where karst groundwater is recharged. Received: 26 March 1997 · Accepted: 22 July 1997     

Karst water resources and geo-ecology in typical regions of China

The aim of this work is to compare the different karst water features and related water resources in South and North China. In Southern China there are over 3,358 karst ground river systems with a total discharge of about 420 × 10⁸ m³ in the dry season. In North China, there are about 100 larger karst spring systems, each with a catchment area from 500 km² to over 4,000 km², and an average discharge from 1 to 13 m³/s. The basic geo-ecological features of water, soil and air quality are described for typical karst regions of China. The total quality of geo-ecology is evaluated by five important factors.     

Composition and variation of major and trace elements in Croatian bottled waters

Within the framework of the Pan-European project about the geochemistry of bottled mineral waters in Europe launched in 2007 by the European Geological Surveys (EGS) Geochemistry Expert Group fourteen brands of bottled natural waters from Croatia of both mineral and spring types were evaluated for getting more coherent spatial information about the natural variation of element concentration in bottled waters found at the European market. Results of chemical analysis show that not a single one out of fourteen analyzed bottled waters from Croatia exceeds the Croatian water standards sanctioning thereby their suitability for human consumption. Also, statistical tests performed for 41 analytes (including pH and EC) clearly show that the water chemistry is in a high degree of conformity with regional geology, depending on structural, stratigraphic and, above all, lithological diversity of aquifers. Thus Dinaric and Pannonian parts of Croatia differ largely with regard to their water types: Dinaric region is completely lacking mineral water types while, on the other side, in the Pannonian region even the spring waters show stronger mineralization in comparison with their Dinaric counterparts. Typically, all natural waters from Croatia bear the bicarbonate (HCO₃) signature. However, Ca–Mg cation pair combination is characteristic of spring waters while Na–K dominates in the mineral waters.     

Influence of sea-water intrusion and agricultural production on the Blato Aquifer,Island of Korčula,Croatia

The Blato aquifer is situated on the western side of the island of Korčula, southern Dalmatia, Croatia. The terrain is built of karstified carbonate rocks, mostly of the Cretaceous age. In the Blatsko karst polje there are four water supply wells with a total yield of about 60 l/s. The catchment area is 28 km². The whole terrain is tectonically disturbed and compressed; the most permeable fracture system is perpendicular to the structural “b” axes, which gives rise to a general groundwater direction towards the island’s northern coast. Average precipitation is 850 mm/year, but when there is less than 700 mm/year there is a high possibility of sea-water intrusion during the summer season. The risk significantly increases when dry years repeat. Hydrochemical research has shown that two main pollution sources occur at different hydrological moments: sea-water intrusion happens in the dry summer period when there is maximal extraction and almost no recharge; and the washing of nitrates and other humanly caused pollution indicators from the soil and epikarst belt during the rainy season. All factors must be taken into account when planning management and protection of such a sensitive environment.     

南方岩溶区地下水资源特征与水资源保障对策

【研究目的】中国南方岩溶地区干旱缺水等问题异常突出,岩溶地下水赋存和分布的复杂,开发利用率低,基于多年调查研究工作为基础,系统总结南方岩溶区地下水资源特征,研讨水资源保障对策。【研究方法】基于南方岩溶区地下水资源特点、地下水系统类型、地下水系统空间结构的叠置性和时空分布不均性分析,提出南方岩溶区水资源保障对策。【研究结果】南方岩溶区可从以下三方面充分发挥地下水资源安全保障作用,一是掌握地下水赋存分布规律,发挥分散供水和应急供水作用;二是加强调蓄工程建设,解决水资源时空分布不均问题;三是建立与生态重建和经济发展相结合的地下水资源可持续利用模式。【结论】南方岩溶区地下水赋存条件复杂,具有表层带岩溶水系统、岩溶地下河与管道流系统、岩溶大泉系统以及分散排泄地下水系统多种类型,规模大小不一,开发利用形式多样;在垂向上具有叠置性,水空分布严重不均;开发利用潜力较大。在地球科学系统论的指导下,查明岩溶水资源赋存分布规律,科学评价地下水资源量,因地制宜制定水资源开发利用和保护方案,为脱贫攻坚、生态文明建设和乡村振兴提供技术支撑。创新点：以系统水文地质环境地质综合调查和地下水开发利用示范工作为基础,系统总结南方岩溶区地下水资源特点;针对岩溶区水资源安全保障问题,分析其主要原因,提出了水资源保障对策。     

Characterizing groundwater flow in a faulted karst system using optical brighteners from septic systems as tracers

This study used optical brighteners (OB) released from septic systems to show that groundwater flow direction is largely controlled by the structural framework in a faulted karst groundwater system. Effective protection of groundwater resources requires that groundwater systems are adequately characterized and source water protection areas (SWPA) are developed for drinking water wells. Karst aquifers are among the most sensitive to contamination due to high recharge rates, and among the most difficult aquifers to characterize due to heterogeneity, and anisotropy. Because septic systems may be used to treat wastewater within SWPAs for karst aquifers there is a need to characterize these groundwater systems using tracers. The objective of this study was to characterize groundwater flow in a faulted portion of the Edwards aquifer in Bexar County, Texas using OB that are released as incidental tracers from septic systems. This study included measurement of water levels, sampling of groundwater and surface water, analysis for OB, and spatial analysis in a GIS. Results show that OB intensities were highest to the southwest of the septic area, a direction that is sub-parallel to the fault and fracture orientation and nearly perpendicular to the hydraulic gradient. This indicates that movement of OB, solutes, or non-aqueous liquids/solids in a faulted karst system can be largely controlled by fault/fracture orientation and structural relay ramps.     

Review: Carbonate aquifers and future perspectives of karst hydrogeology in India

About 3 % of India’s total land surface is occupied by carbonate rocks which are mostly karstified and constitute a significant source of groundwater. The groundwater drawn from these aquifers matches the water demand of ~35 million people living in 106 districts of the country and also the water needs of livestock, irrigation and industry. The studies on karst in India carried out so far have mostly addressed geology, hydrology and groundwater contamination. A literature survey suggests that there is a need for detailed research, applying new approaches and techniques for proper carbonate aquifer identification, characterization and management. Such specific approaches will improve modeling, exploitation and protection of karst groundwater. An overview of the research carried out on groundwater resources of karst formations in India is presented, which also throws light on the protection of karst aquifers from existing anthropogenic activities such as mining and groundwater over-exploitation.     

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.     

Management of karst aquifers in Serbia for water supply

Karst aquifers represent one of the main sources of water supply in Serbia. Wide distributions of karstic areas, abundant reserves, and excellent quality of karst groundwater have been the reasons for its extensive use in water supply systems throughout the country. In Serbia, 70 karstic sources have been tapped for centralized water supply, with the assessed minimal capacity exceeding 4.5 m³/s. Most of the large cities of Eastern and Western Serbia currently use karst groundwater for water supply; however, due to unstable flow regime when only natural springflow is tapped, numerous problems arise during the recession period (summer–autumn). During the last two decades, after favorable conditions had been confirmed through hydrogeological survey and feasibility studies, several newly constructed systems for artificial control of karst aquifers (mostly in Eastern Serbia) resulted in significantly improved water supply.