Carbonate coastal aquifer of Vlora bay and groundwater submarine discharge (southwestern Albania)

Abstract

The study discusses the large karstic coastal aquifer of Vlora Bay. This case is peculiar, as the submarine groundwater discharge has a relevant rate of terrestrial inflow in an almost closed bay that is located in an environmentally valuable area. The study is based on four methodological activities: geological and hydrogeological conceptualisation, climatic study and hydrological balance, numerical modelling, and monitoring. A geodatabase was created considering hundreds of data points (wells, springs, rivers, lagoons, and seas) and monthly time series of rainfall, temperature, and river discharge. Monitoring activity was realised over a hydrological year, installing a rainfall network tool and using a network of tens of sampling points, including springs, wells, lagoons and sea. Chemical-physical and stable isotope determinations were realised. Two main groups of aerial springs are fed by the aquifer, one of which is of a coastal type. The total spring discharge is roughly 4 m3/s. The GSD was assessed as being equal to 1.4 m3/s on the basis of the current rate of anthropic discharge and climatic conditions. The study showed the peculiarities of this carbonate coastal aquifer and the importance of its groundwater, which is the chief water source for the third-largest Albanian town. The groundwater quality was generally high, mainly due to the negligible presence of contamination sources on the relief in which the aquifer outcrops. The rate of seawater intrusion effects was also low, thanks to favourable aquifer 3-D geometry and high recharge levels. The increasing anthropic activities constitute a relevant risk in the absence of the introduction of rigorous land and water management criteria.