Impacts of simultaneous action of drought and overpumping on Quaternary aquifers of Glafkos basin (Patras region, western Greece)

 The Glafkos river basin extends southeast of Patras and is the city's main groundwater reservoir. In the last few years, a steady decline of the groundwater level has been observed in 19 wells due to overpumping and prolonged drought periods. The present paper assesses the adverse simultaneous effects of drought and overpumping on the groundwater regime. Analysis of the rainfall data of the last 60 years shows a decrease of precipitation during the last decade. Runoff measurements show a decrease in the outflow of the Glafkos river. The increased water pumping and the decrease of recharge during the last decades have resulted in depletion of the aquifers. Chemical analyses showed a constant reduction of the groundwater quality. Comparison of piezometric maps of two periods with a 19-year interval shows a clear decline of the general piezometry as a result of overpumping and drought. Received: 11 January 1995 · Accepted: 21 November 1995