RAINFALL-LOSS PARAMETER ESTIMATION FOR ILLINOIS.

The U. S. Geological Survey is currently conducting an investigation to estimate values of parameters for two rainfall-loss computation methods used in a commonly used flood-hydrograph model. Estimates of six rainfall-loss parameters are required: four for the Exponential Loss-Rate method and two for the Initial and Uniform Loss-Rate method. Multiple regression analyses on calibrated data from 616 storms at 98 gaged basins are being used to develop parameter-estimating techniques for these six parameters at ungaged basins in Illinois. Parameter-estimating techniques are being verified using data from a total of 105 storms at 35 uncalibrated gaged basins.