Forecast Changes in Runoff Quality and Quantity from Urbanization in the DelMarVa Peninsula: Fid-Bau Portal

Forecast Changes in Runoff Quality and Quantity from Urbanization in the DelMarVa Peninsula

Ciavola, Suzanne J. / Jantz, Claire A. / Reilly, James / Moglen, Glenn E.

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 storm water runoff that will inevitably follow. This study is a regional attempt at predicting how changes in land use will affect runoff characteristics in 17 watersheds throughout the Delaware-Maryland-Virginia (DelMarVa) Peninsula when compared to the current conditions. The authors coupled demographic and urban growth models to create maps showing the location of predicted urban land use for the year 2030, and then used nutrient loading and rainfall-runoff models to forecast the consequences of such growth on the magnitude of changes that can occur in runoff quality and quantity. The authors found that likely change in urban land use would lead to decreases in sediment and nitrogen loads by up to 8 and 37%, respectively; that phosphorus loads would increase or decrease depending on the type of existing land use that was replaced by urban land use; and that the 2-year peak flow would change by 2–9% across all scenarios, whereas relative changes to flood peaks for the 100-year peak flows were considerably smaller. Sensitivity analysis also was performed. The authors’ modeling provides a planning-oriented look into the effects of increased urban development on the predominantly agrarian study area, the majority of which drains to the Chesapeake Bay. The modeling also illustrates a useful approach for evaluating consequences of future planning and management decisions within a desired region.