Specificities of coastal karst aquifers with the hydrogeological characterisation of submarine springs–overview of various examples in the Mediterranean basin (original) (raw)
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Geosciences, 2018
Coastal karst aquifers are common in the Mediterranean basin. With their significant potential storage capacity, they are an attractive groundwater resource in areas where the water demand is the most important. They discharge either at the coastal zone or directly into the sea at karst submarine springs (KSMS). Decision makers take an interest in this unconventional groundwater resource and are convinced by companies and research consultancies that KSMS's should be exploited because they would discharge huge amount of fresh water. Being now well documented, the occurrence of KSMS's along the Mediterranean coast is discussed in the light of recent geological history favourable to the development of karst. Conduit flow conditions are common, inherited from an intense phase of karstification during the Messinian Crisis of Salinity at the end of Miocene, when the sea level was 1500 to 2500 m below present sea level. From investigations carried out along the coasts of France and the Levant, compared with studies done along other Mediterranean coastlines, it appears that capturing groundwater discharged at KSMS raises different problems which make the operation dicey and expansive.
In coastal regions, the study of karst aquifers and the ground water resource exploitation require a specific methodology and exploration and monitoring techniques. Two directions are investigated, leading to new technological and methodological developments. The first investigation axis deals with the exploration of fresh water plumes from submarine karst springs. An Autonomous Underwater Vehicle (AUV) is being developed and tested in order to collect all data (salinity, temperature and depth) along its trajectory. The submarine discharge may be estimated by modelling. The second axis deals with the water works for collecting the submarine fresh water discharge. The capture system is designed for monitoring the spring discharge, salinity, temperature, radon concentration and turbidity. The data time series will be analysed in order to determine the aquifer functioning. Discharge data will be used for simulating the spring flow in function of rain series. The prototypes are presently being developed and tested.
2003
In coastal regions, the study of karst aquifers and the ground water resource exploitation require a specific methodology and exploration and monitoring techniques. Two directions are investigated, leading to new technological and methodological developments. The first investigation axis deals with the exploration of fresh water plumes from submarine karst springs. An Autonomous Underwater Vehicle (AUV) is being developed and tested in order to collect all data (salinity, temperature and depth) along its trajectory. The submarine discharge may be estimated by modelling. The second axis deals with the water works for collecting the submarine fresh water discharge. The capture system is designed for monitoring the spring discharge, salinity, temperature, radon concentration and turbidity. The data time series will be analysed in order to determine the aquifer functioning. Discharge data will be used for simulating the spring flow in function of rain series. The prototypes are presently being developed and tested.
Environmental Earth Sciences, 2015
The study and management of the groundwater resources of a large, deep, coastal, karstic aquifer represent a very complex hydrogeological problem. Here, this problem is successfully approached by using an equivalent porous continuous medium (EPCM) to represent a karstic Apulian aquifer (southern Italy). This aquifer, which is located on a peninsula and extends to hundreds of meters depth, is the sole local source of high-quality water resources. These resources are at risk due to overexploitation, climate change and seawater intrusion. The model was based on MODFLOW and SEAWAT codes. Piezometric and salinity variations from 1930 to 2060 were simulated under three past scenarios (up to 1999) and three future scenarios that consider climate change, different types of discharge, and changes in sea level and salinity. The model was validated using surveyed piezometric and salinity data. An evident piezometric drop was confirmed for the past; a similar dramatic drop appears to be likely in the future. The lateral intrusion and upconing effects of seawater intrusion were nonnegligible in the past and will be considerable in the future. All phenomena considered here, including sea level and sea salinity, showed non-negligible effects on coastal groundwater.
Karst hydrogeology of the Kaş-Kalkan springs along the Mediterranean coast of Turkey
Environmental Geology, 1998
The present studies were carried out along the southern Mediterranean coast of Turkey, where most of the karst springs discharge from highly karstified carbonate rocks. The case-study was applied in the Kaş-Kalkan karst region, considered one of the most important touristic Mediterranean provinces in southern Turkey. The purpose of this study is to identify the main water resources of the karst springs in the inland side and the expected groundwater flow paths that may recharge the coastal springs in the study area. A comparison of the physiochemical properties and isotopic contents of the karst springs along the Kaş-Kalkan coastline is also considered an important tool for identifying the hydrogeological characteristics and responses of the different units in the study area. Relevant studies were carried out also considering the morphological and structural characteristics of these karst springs and changes in their discharge amounts during the dry and wet periods.
Hydrogeology …, 2011
A 120 km-long part of the southwestern coast of Turkey, with well-developed karst terrain in contact with the sea, has been investigated by systematic diving surveys to determine the submarine groundwater discharges (SGDs). The physical, chemical and isotopic data have been used to determine the rate of the fresh groundwater end member (FEM) and its temporal dynamics. About 150 SGDs have been detected by diving surveys employed mostly up to a depth of 30 m below sea level (bsl). Among those, 15 SGDs are in the form of coastal or submarine caves with entrances ranging between sea surface and 40 m bsl. The FEM contribution in SGDs ranges from a few percent to more than 80%.
Environment, Development and Sustainability, 2023
This study aims to present the hydrogeological and hydrochemical characteristics of Paradisos Karst aquifer system (PAS), Northeast Greece. The average area of the PAS is estimated according to Thornthwaite and Mather (1957) (T-M) procedure at 74.2 km 2. The karst system, which is largely fault-controlled, discharges through three permanent karst springs: KS15, KS20 and KS21. The average discharge rate was calculated for two of them at 0.726 m 3 /s. The time series analysis shows that: (a) the memory effect for the PAS is extremely high; and (b) the karst system is a poorly developed with high storage capacity and absence of a quick flow component. The chemical type for the majority of the groundwater samples is of Ca-HCO 3 type. The chemical properties of the groundwaters are strongly influenced by alkaline earth metals and weak acids. The presence (sporadically) of high NH 4 + content and slightly increased nitrate, ammonium and phosphate values in springs KS20 and KS21 is attributed to the presence of anthropogenic sources, especially septic tanks and agriculture. All studied groundwaters are oversaturated in calcite and aragonite, which suggests a mechanism of diffuse flow. The morphology and geology of the PAS catchment area, and data from hydrographs and chemographs, show that the hydrologic system is dominantly of diffuse flow. The use of time series analysis combined with classic hydrogeological techniques (i.e., degree of karstification, T-M procedure, chemographs and
Isotopes in Environmental and Health Studies, 2005
The Lamas Basin is an area covering ∼4400 km 2 situated on the eastern Mediterranean coast of Turkey covered with highly karstified limestone and dolomitic limestone from the Miocene and Mesozoic age, respectively. Owing to the area's low karstification basement, groundwater in the karst aquifer circulates deep from the surface towards the springs along the coast as well as to the submarine springs.