State Water Resources Research Institute Program
Project ID: 2012DC138B
Title: Development of a physically-based model for Performance Evaluation Optimization of Green Roof Systems
Project Type: Research
Start Date: 3/01/2012
End Date: 2/28/2013
Congressional District: DC
Focus Categories: Education, Hydrology, Non Point Pollution
Keywords: Stormwater, Low impact development, Green roofs, Flow in unsaturated media, Contaminant fate and transport
Principal Investigators: Massoudieh, Arash; Behera, Pradeep K.
Federal Funds: $ 9,230
Non-Federal Matching Funds: $ 32,517
Abstract: The main role of low impact development (LID) practices in the context of sustainable urban stormwater management is to reduce the volume and the peak flow rate of stormwater hydrographs. Achieving these goals has multiple environmental benefits to the receiving waters, including the reduction of the high contaminant concentration discharge during the first-flush period, erosion reduction, reducing flood risk and, most importantly, decreasing the frequency of emergency bypass operations of non-treated stormwater in case of presence of combined sewer systems and limited waste water treatment plant capacity.
These environmental benefits become more pronounced in highly urban areas like Washington, DC, where the majority of the city is a combined sewer network. The District of Columbia bypasses large amounts of non-treated stormwater into the surrounding waterways, including the Anacostia and Potomac Rivers and the Rock Creek stream. For these reasons, implementation of LID practices such as green roofs has been promoted by the city.
Tools that predict the performance of various designs of green roofs are essential in evaluating their effects on improving the overall stormwater quality and also for finding the design parameters of these LIDs, resulting in their optimal effectiveness. The modules representing the behavior of LIDs in commonly-used stormwater modeling programs such as SWMM (Rossman, 2004) are still extremely simplified and cannot capture many of the processes affecting the water retention behavior of the LIDs.
Our goal is to develop a physically based model for predicting flow of rainwater and transport and retention of nutrients as a result of application of fertilizers and pollutants associated with wet and dry deposition in green roofs. The model will be calibrated and validated using the data collected by the team under supervision of Dr. Pradeep Behera at UDC. Dr. Behera's team is planning to conduct extensive monitoring on the green roof structures recently constructed on the UDC campus. The modeling tool developed will allow us to interpret and generalize the data obtained during the monitoring. The outcome of this study will be used as preliminary data for a larger proposal to EPA, NSF or the District Department of Environment.