Spring Discharge and Aquifer Characteristics in a Sandy Till Area in Southeastern Sweden

Abstract

Spring discharge and groundwater levels were used to study groundwater outflow recessions, groundwater reservoir sizes, water yielding properties and saturated hydraulic conductivities in a sandy till area in southeastern Sweden. Water chemistry was used as an indicator of flow paths. The catchment areas of the five springs, ranging from approximately 0.01 km2 to 0.2 km2 in size, were all mainly covered with coniferous forest. The maximum active groundwater storages of the catchment areas of the springs varied from 75 to 145 mm. As a comparison the maximum total groundwater storage of the till in the catchment area of the largest spring was estimated to 1,250 mm. Two springs were chosen for detailed studies. The highest peak discharge of the smallest of these springs was 1.7 mm/day and it usually dried up in summer. The discharge from the largest spring was evenly distributed and varied between 0.2 and 0.8 mm/day. Frequent analyses of water chemistry during a spring with intense snowmelt revealed no change of water composition in spite of a great increase in discharge; for the smallest spring by more than 30 times. Integrated values of the specific water release from the unsaturated zone to the groundwater reservoir were calculated from runoff volumes and decreasing groundwater levels for the catchment area of the largest spring. The different values obtained from dry summer and winter periods, 0.024 and 0.047 respectively, indicated a strong influence from evapotranspiration. It the same spring, an areally integrated value of the saturated hydraulic conductivity was estimated to 6 × 10−5 m/s from a linearized solution of the Boussinesq equation.