THE EFFECTS OF URBANIZATION ON THE HYDROLOGY OF A MEDIUM SIZED WATERSHED: AN EXAMPLE FROM NORTHWEST OHIO

Aerial Photography from three Decades (1973, 1988,1995) has been used to investigate the effects of urbanization on the hydrology of a medium sized watershed. Greater than 20 percent of the 531-km2 Swan Creek Watershed in Lucas Co. Ohio, has experienced urbanization in the study's 27-year period. Results of this study show that the urbanization has changed from 70% agricultural land-use to 50% urbanized land-use within the watershed with consequent increases in the effective flooding return rates and increases the spatial extents of the local flood zones. The study combined GIS technology with the Army Corps. Hydrologic Engineering Center (HEC-RAS) modeling system to provide a detailed analysis of the effects of land-use changes on the hydrology based on a 1973 flood event in the watershed and the predicted 100 year storm event. The study shows that combination of Remote Sensing, GIS and Hydrologic Modeling is a effective tool for assessing the impacts of urbanization in a watershed.