Ground-water resources of the White River basin, Delaware County, Indiana

The ground-water resources of the White River basin in and near Delaware County, Indiana, were investigated by mapping the aquifers, calculating their hydraulic properties, determining the distribution of potentiometric head, and determining some of the components of the ground-water budget from data collected in the field. This information was used to construct and calibrate a seven-layer, digital ground-water-flow model. The model, constructed and calibrated to water-level and seepage data collected during the study, simulates conditions for the autumn of 1977. The model was used to assess ground-water potential in terms of yield, drawdown, and streamflow depletion.

Drift covers nearly the entire area and generally ranges in thickness from 0 to 500 feet. Beneath the drift lie Silurian and Ordovician limestone, dolomite, and shale. A bedrock valley trends east-west through the center of the area. Bedrock surface relief is about 400 feet.

Six confined sand and gravel aquifers interbedded in the drift, a bedrock aquifer, and an unconfined outwash aquifer are the three major aquifer systems. The nearly horizontal, areally discontinuous, confined sand and gravel aquifers generally range in thickness from 5 to 40 feet and have an average hydraulic conductivity estimated to be 433 feet per day. The bedrock aquifer underlying all of Delaware County has a permeable thickness estimated to be 150 feet and an average transmissivity of 1,000 square feet per day.

Observation-well records indicate that water-level fluctuation is seasonal and has no long-term trends. Municipal and industrial ground-water pumpage for 1976 was 3.1 million gallons per day (4.8 cubic feet per second). On October 29, 1977, when the flow duration in the White River at Muncie was 80 percent, ground-water seepage to streams was 81 cubic feet per second. The water budget simulated in the model indicated that the rate of inflow to the ground-water system in the modeled area is 102 cubic feet per second: 80 percent from effective areal recharge of precipitation and 20 percent from ground-water flow across the area boundaries. Two percent of the ground-water discharge is pump-age, 66 percent is seepage to streams, and the remaining 32 percent is flow across the area boundaries.

Simulations of seven pumping plans provide a general assessment of the water-yielding potential of the three major aquifer systems. Model results indicate that as much as 3 million gallons per day can be developed from well fields where the average drawdown is 20 feet. Model simulations also indicate that 7 million gallons per day is available from a potential well field around Muncie.