Groundwater resident time in the catchment area with artificial drainage system in the crystalline rock environment
Abstract
In the Dehtâre catchment area with extensive agriculture exploitation a groundwater outflow and residence time were studied in 2004-2006. The area is located in crystalline rocks, with characteristic unconnected water saturated zone and local flow. The catchment area is characterized by 32.6 % weep drain. Nitrate concentration in groundwater together with CFCs, SF6, oxygen stable isotopes and tritium concentration were used to estimate the proportion of modern water in the supply artificial drainage system and wells. The artificial drainage system contains about 80 % groundwater with resident time 5-20 years and 10-20 % groundwater with resident time 5-13 months.