Using SLEUTH Land Cover Predictions to Estimate Changes in Runoff Quality and Quantity in the Delmarva Peninsula

Anticipating future trends in land development and climate change is a constant challenge for engineers and planners who wish to effectively compensate for the resulting changes in stormwater runoff that will inevitably follow. This study is a regional attempt at predicting how predicted changes in land cover will affect runoff characteristics in a number of watersheds throughout the Delmarva Peninsula when compared to the current state. To predict changes in land cover and the associated land use, the SLEUTH model coupled with PED utilized a number of different inputs including population growth trends, existing geography, current land planning policies as well as different growth factors to predict where urban growth is most likely to occur. The model creates maps which show the approximate location of predicted growth for the year 2030.

Using SLEUTH output, the magnitude of changes that can occur in runoff quality and quantity due to land cover changes were estimated in each of the seventeen representative watersheds that were chosen within the Delmarva Peninsula. Changes in water quality were calculated based on nutrient loading rates for sediment, phosphorus, and nitrogen. These nutrient loading rates correspond to different land uses within different county segments in the peninsula. The expected changes in water quantity were quantified using the United States Department of Agriculture's Natural Resources Conservation Services' TR-20 which estimated the peak flows for each watershed based on watershed's size, land cover, soils, and slope.

Evaluating the magnitude of these potential changes in the Delmarva Peninsula provides an important look into the effects of increased urban development on the predominantly agrarian land mass, the majority of which drains to the Chesapeake Bay.