Measuring Watershed Land-Use Changes with Airphotos

Aerial photographs were used to determine land-use changes over a 25-yr period in two watersheds in western South Carolina. The North Tyger River watershed near Spartanburg, S.C., experienced changes in agricultural land use and the Reedy River watershed exhibited a conversion of rural land use to urban land use because of the urbanization occurring in the Greenville, S.C. urban area over the study period. Aerial photographs taken at approx 5-yr intervals were used to classify and measure the areas of various land-use classes in the two watersheds. The individual land-use parcels were measured by using a planimeter on aerial photographic enlargements. Significant changes in land use were observed in the two watersheds, changes that would be expected to have an important effect on the hydrologic response of the watersheds. The results obtained from the study indicate that the use of aerial photographs represents a satisfactory approach.