A HYDROLOGIC MODEL FOR LOWER COASTAL PLAIN WATERSHEDS, SOUTHEAST UNITED STATES

A disributed, physically-based, watershed hydrologic simulation model, called COASTAL, has been specifically designed for use on watersheds of low relief where streamflow is supplied predominantly by ground water discharge. To use the model, the watershed is divided into square grid elements that are modeled by the lumped parameter approach. I nput data include daily temperature, daily precipitation, topographic elevation, soil field capacity, soil wilting point, aquifer hydraulic conductivity, aquifer thickness and land use for each grid element and a watershed stream rating curve. One or more years of daily streamflow data are needed to calibrate the model. Yearly correlation coefficients between measured and simulated daily streamflow averaged 0.85 and ranged from 0.70–0.91 in tests of the model using 1957-1964 data for the Hurricane Creek watershed, Georgia. Correlation coefficients between measured and predicted annual, monthly, and annual maximum streamflow for the eight years tested were 0.97, 0.93, and 0.82, respectively.