Land Use Change: Impact of Vegetative Cover On Rainfall Interception and Groundwater Recharge Dynamics.

Irrigated land area has steadily increased over the past 50 years in Central Wisconsin Sand Plain as prairie and forest land covers have been converted to irrigated agricultural crops.  During the past decade, the water quantity in area lakes and rivers decreased significantly in the Sand Plains. Groundwater recharge rates are influenced by a variety of factors specific to ground cover which obscure the impact of irrigation on groundwater levels. Irrigated lands evapotranspire more water than perennial vegetation during the growing season. However, greater recharge is possible on irrigated lands during bare soil periods late fall and early spring.  To investigate these phenomena for perennial vegetation and cropped lands we used the Integrated Biosphere Simulator (IBIS) model. This model incorporates a wide range of physical properties including land surface physics, canopy physiology, plant phenology, vegetation dynamics and competition, and carbon and nutrient cycling. To validate the simulations we  are measuring precipitation, soil water content and ground water levels at eight sites including mature mixed prairie with tree (>50 years), restored prairie (<5 years), mature pine plantation, five irrigated crops: potato, oats, sweet corn, and two soybean fields. Quantifying the impact of irrigated fields on water balance will provide more information to better manage water resources of the Central Wisconsin Sand Plain.