An Integrated Field Assessment of Groundwater Recharge

Groundwater recharge is often assumed to be uniform within a watershed owing to difficulties in quantifying its temporal and spatial variability. In this paper, fluctuations in soil moisture content at multiple depths in the unsaturated zone together with fluctuations in the water table are used to provide a record of the recharge process and a means to quantify and compare temporal and spatial recharge variability. Hourly measurements of soil moisture content and the elevation of the water table were collected at two sites, a clear cut and a coniferous forest site, within the Trout Lake basin of northern Wisconsin. The soil moisture and water table data were used together to assess the temporal and spatial vari- ability in groundwater recharge from October 1999 to May 2001 and to identify the climatic (amount and timing of rain- fall) and physical (vegetation and soil type) controls on the recharge process within this basin. Together, the two datasets allow for a holistic assessment of the recharge process from the ground surface through the unsaturated zone down to the water table.