Groundwater flow model of the northern part of the Lushnja aquifer in Albania

Abstract

The western part of Albania along the Adriatic Sea is bordered by coastal lowlands that are underlain by gravel deposits of Quaternary age. These deposits comprise very permeable and laterally extensive aquifers that contain large quantities of good quality groundwater that can be exploited by means of inducing infiltration from rivers. In west-central Albania, the Lushnja plain is underlain by such an aquifer (the Lushnja aquifer), which is bounded on the north by the Shkumbin River, on the west and east by the Divjaka and Dushku hills, and on the south by the Patosi hills and the Seman River. A numerical model using the finite difference method with an implicit solution technique was used for the first time in Albania to simulate groundwater flow in the northern part of the Lushnja aquifer. During the calibration process, for existing conditions, the recharge from the Shkumbin River was determined to be 0.090 m3s−1. Other inflows to the aquifer in the model totalled 0.066 m3 s−1The flow rate of exploitation wells in the town of Dushku was determined to be 0.125 m3 s−1 as a calibration parameter, and the pumping rate of other wells totalled 0.031 m3 s−1. In the calibrated model, the transmissivity of the aquifer ranged from 0.0029 to 0.041 m2s−1, and the leakance of the riverbed (i.e. the vertical hydraulic conductivity/thickness of the riverbed) of the Shkumbin River ranged from 1.1 x 10−6 to 3.5 x 10−6 s−1. After the model was calibrated, it was used to simulate the potentiometric surface that would result due to pumping 0.565 m3 s−1 from exploitation wells proposed for the city of Lushnja and for local needs.