Effects of Increased Groundwater Pumping On Lake Elevations, River Stages, and Spring Flows in Central Florida

Groundwater pumping from the Floridan aquifer system has increased steadily in central Florida from 1995 to 2006. Population increases result in additional aquifer stresses that cause decreased potentiometric surface levels in the Floridan aquifer system. Decreases in stream stages, stream flows, spring flows, and lake elevations result from increases in groundwater pumping. A groundwater flow simulation based on MODFLOW-2005 was developed to assess the effects of groundwater pumping on lake elevations, stream stages, and spring flows using the lake, streamflow routing, and general-head boundary packages. Evapotranspiration and rainfall data from 1995 to 2006 were used to simulate the coupled effects of groundwater pumping and atmospheric changes. Water-level data from 1995 to 2006 in central Florida were used to calibrate the groundwater flow model. Measured and simulated groundwater evapotranspiration were compared to analyze the relation between decreases in water-table altitude, lake elevations, stream stages, stream flows, and spring flows and changes in estimated actual evapotranspiration and areally estimated rainfall. Results indicate that long-term increases in groundwater pumping can be linked to long-term decreases in surface water levels, groundwater discharges to streams, spring flows, and measured evapotranspiration.