Showing papers by "Christoph Schüth published in 2015"

Application of GALDIT index to assess the intrinsic vulnerability to seawater intrusion of coastal granular aquifers

Abstract: Groundwater within coastal aquifers is considered a very sensitive natural resource since its quantity and quality is threatened by anthropogenic activities as well as global and climate changes. The major environmental hazard with respect to coastal aquifers is the phenomenon of seawater intrusion, and is more pronounced in the Mediterranean basin. In the light of smart management of such hydrogeological systems, GALDIT index was introduced in the form of a numerical ranking system that aims to assess the vulnerability of such aquifers to seawater intrusion. This paper provides an application of GALDIT vulnerability index for a typical Mediterranean alluvial aquifer under variable hydrogeological conditions in different research periods (1992 and 2004). The results proved the significance of the piezometric conditions of the aquifer with respect to its vulnerability to seawater intrusion.

Groundwater vulnerability assessment of a coastal aquifer system at River Nestos eastern Delta, Greece

Abstract: Processes such as urbanization, agricultural development and industrialization have led to increasing demand of groundwater resources resulting in pollution threats to groundwater in different ways, either as contaminant loads on the ground surface, or as seawater intrusion due to overexploitation of wells in the coastal zone. Two groundwater vulnerability indices are applied in this paper to assess the potential risk of groundwater contamination in the eastern delta of Nestos River, Greece. DRASTIC model is used in this paper to evaluate the groundwater vulnerability of the area with focus on agrochemical contaminants, more especially on nitrate pollution, since the region is highly cultivated. Additionally, GALDIT index is also applied to assess the vulnerability of the freshwater aquifer to seawater intrusion, as the extensive pumping of the coastal wells has led to this phenomenon. The vulnerability assessment showed that the study area experiences low to moderate groundwater vulnerability to agrochemical contaminants, as well as moderate to high vulnerability to seawater intrusion. The use of GIS for both vulnerability indices was found effective for the evaluation of each method in comparison to real field data.

The impact of hydrogeological settings on geochemical evolution of groundwater in karstified limestone aquifer basin in northwest Sri Lanka

Abstract: The geochemical and isotope analysis of groundwaters from the Murunkan basin in north western Sri Lanka was carried out to examine their evolution and recharge sources in order to shed light to enhance the current knowledge of the hydro-geochemical processes in a karst geological setting. A total of 40 water samples from ground and surface water bodies were collected from the Miocene limestone terrain, nearby metamorphic and from unconsolidated Quaternary terrains for major anions, cations and environmental isotopes ratios (δ18OVSMOW and δ2HVSMOW). Distinct geochemical differences were noted between waters from limestone terrain and nearby metamorphic terrain indicating the modification of groundwater flow paths. Bicarbonate-chloride rich water is dominated in the limestone terrain in which water flows through a less mineralized aquifer system and is modified by the sea water intrusion. Groundwater in the metamorphic terrain is modified by dissolving of Ca–Mg rich mineral phases and subsequent ion exchange processes. The environmental isotopes of groundwater from both limestone and metamorphic terrains vary from −0.38 to −6.68 ‰ and −2.41 to −42.3 ‰ for δ18OVSMOW and δ2HVSMOW, respectively. However, slightly enriched isotope signatures and low d-excess values from limestone terrain indicate an excessive evaporation compared to that of the metamorphic terrain where rapid infiltration occurs through the overlying highly permeable grumusols soil layers.

Spatial variation of boron in groundwater in South Iraq

Abstract: The research investigated boron variability in space and time, using 450 groundwater samples from 75 representative wells in the Safwan–Zubair area of Basra district, South Iraq, collected monthly from January to June 2000, with also 75 soil samples from selected farms in the same area. Minimum and maximum values of boron concentrations range from 1.49 to 9.49 ppm respectively. Boron concentration in groundwater spatially occurs in 90% in frequency between 2 and 4 ppm, while 5% below 2 ppm and 5% is more than 4.0 ppm to more than 9.0 ppm, where the soluble boron concentrations of soil samples range from 0.60 to 7.02 ppm. Soil boron concentration spatially occurs 95% below 6.0 ppm and 5% more than 6.0 ppm. The results show that the variability of boron concentration in groundwater and in soil mostly depends upon irrigation water, cyclic differences of the sediment facies horizontally and vertically, and also the period of precipitation (rainfall); i.e. wetting and drying processes. The results indicate tha...

Isotopic composition of Riyadh rainfall, Saudi Arabia

Abstract: Arid countries like Saudi Arabia often depend on fossil groundwater. Hence, thorough studies of the available resources are crucial. In the course of such investigations, analyses of δ18O and δD are frequently applied to constrain the provenance of the waters and to reconstruct the (paleo)climatic conditions during their recharge. Yet, to be able to evaluate the isotopic signature of the groundwater, one also has to know the isotopic composition of current precipitation. Although a few rain water analyses are available for Central Saudi Arabia in the literature – mostly in unpublished consultant reports – a Local Meteoric Water Line has never been established. To complement the available data, 28 rain events occurring in Riyadh between 2009 and 2013 were studied for their stable isotope composition. Samples were collected as integral samples, i.e. they represent the entire precipitation event. Moreover, one event was sampled several times, aiming at an evaluation of intra-storm variability. During selected storms, a grab sample was taken for 3H analysis. The event samples showed δ18O and δD values scattering between -6.5 and +9.5 and between -30 and +50 h V-SMOW, respectively. In the course of the event that was sequentially sampled, a proceeding isotopic depletion was observed with respect to both isotopes. The relatively large ranges of δ-values for 18O and D of approximately 7 and 38 h V-SMOW highlight the general need for integral sampling. The obtained grab samples are characterized by moderate 3H concentrations of a few Tritium Units. Further results will be presented and discussed in view of associated weather data (e.g. rain amount and temperature) and the probable moisture sources derived from back-trajectories, which were calculated using HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory Model; Draxler & Rolph, 2003).