Author(s): Tatiana Orehova; Elena Bojilova
Linked Author(s):
Keywords: Groundwater; Drought impact; Spring discharge and water level
Abstract: The purpose of the present contribution is to clarify the influence of the recent drought period (1982 -- 1994) on groundwater in Bulgaria. Taking into account the global climate change conception, this period may be considered as a model of future behavior of water resources. The groundwater regime in Bulgaria is described over the three main territorial units: Danube hydrological zone, Black sea zone and Aegean hydrological zone. The investigation is based on available long-term observations (from 1960 up to1999) for springs and wells without significant impact of human activity. Time series of spring discharge and groundwater level in wells were processed. The chronological structure of the respective time series was investigated. Most karstic springs had reduced discharge (15-25% in average) and wells showed lowering of the water table (0.20-0.30 m) during the 1982 -- 1994 drought period. The strongest reduction in spring discharges is registered during 1985 -- 1994period. The situation is similar with water levels in wells. The corresponding values are 25-45 % and 0.30-0.45 m. From 1996 -- 1997 the annually average discharges and groundwater levels have tendency to reach their multi-annual average values. These phenomena took place as a result of the continuous period of decrease in rainfall in combination with increase in air temperature registered in Bulgaria since 1981. According to scenarios of Climate change given in Arnell, 1999, the reduction of river flow in Bulgaria with 25-50% is expected. These results are comparable to the effect of the drought period 1982 -- 1994 for the groundwater. The general conclusion is that the drought period reflected considerably on the groundwater. The reductions in spring flows were registered as well as lowering of groundwater levels. The results obtained give an idea of the reduction in aquifer recharge in condition of global climate change.
Year: 2001