Using remote sensing imagery to determine the impact of land cover changes on potential runoff for the Mid-Cibolo Creek watershed,Texas

Land cover changes within watersheds have the potential to produce dramatic changes in surface hydrology, namely runoff, in the event of storms. The Mid-Cibolo Creek watershed in south-central Texas has experienced extensive land-cover change in the past two decades due to mass residential development and land clearing in the wake of urban growth along the I-35 corridor. This study determined land-cover changes within the basin using supervised classification to classify land cover from LANDSAT images for the years 1986 and 1999. Changes in runoff volume were then calculated using the Soil Conservation Service (SCS) runoff equation for a series of rainfall scenarios. The results showed that an overall increase in impervious cover and decrease in natural vegetative cover has occurred leading to larger runoff volumes for all storm scenarios. The findings are important for watershed scale urban expansion and land clearing practices as current methods suggest that flood risk is increased.