Effectiveness of Design and Implementation Alternatives for Stormwater Control Measures Modeled at the Watershed Scale
Citation:
Almadani, M., C. Nietch, AND A. Massoudieh. Effectiveness of Design and Implementation Alternatives for Stormwater Control Measures Modeled at the Watershed Scale. Journal of Sustainable Water in the Built Environment. American Society of Civil Engineers (ASCE), New York, NY, 9(1):04022021, (2023). https://doi.org/10.1061/JSWBAY.SWENG-460
Impact/Purpose:
To evaluate the effectiveness of dispersed stormwater control measures (SCMs) it is important to consider groundwater-surface water interactions and their consequences for stream hydrologic responses relevant to channel geomorphic stabilty and ecology. A process-based block-connector model of an urban watershed (29 km2) in the suburbs of Washington, DC, was used to study the effects of SCM system design on flows in Sligo Creek. The results are relevant to planning-level decisions that depend on effectiveness predictions of different SCM unit designs and implementation alternatives in developed watersheds.
Description:
To evaluate the effectiveness of dispersed stormwater control measures (SCMs) it is important to consider groundwater-surface water interactions and their consequences for stream hydrologic responses relevant to channel geomorphic stabilty and ecology. A process-based block-connector model of an urban watershed (29 km2) in the suburbs of Washington, DC, was used to study the effects of SCM system design on flows in Sligo Creek. The watershed has 34% impervious area (IA), which was categorized along with pervious areas and then discretized into 14 similar-sized subwatersheds. Each was compartmentalized with representative overland flow, unsaturated flow, and groundwater blocks and connections to main channel segments. The model was calibrated and validated to existing conditions using a 3yr time series of observed flow data. Afterwards a predevelopment simulation was configured, and then different combinations of SCM unit designs and IA diversion alternatives through the SCM system were simulated. Unit design scenarios represented a simple pond with surface storage and overflow or ones that also infiltrate with an engineered soil layer and with or without an underdrain pipe. Differences among the model simulations were evaluated using flow exceedance probability curves. The SCM system was modeled as 5% retrofit to IA. The results showed that at least a 50% diversion of runoff from IA watershed-wide would be needed to achieve similar predevelopment baseflows and peak flows. Intermediate flows could not be matched but were closest for the infiltration with underdrain pipe design scenario. However, in a simulation that diverted 90% of IA through SCMs in the lower half of the watershed only, which translates to a less than 50% implementation of SCMs watershed wide, the predevelopment conditions were the most closely matched with the simple pond and infiltration without underdrain pipe scenarios. The results are relevant to planning-level decisions that depend on effectiveness predictions of different SCM unit designs and implementation alternatives in developed watersheds.
URLs/Downloads:
DOI: Effectiveness of Design and Implementation Alternatives for Stormwater Control Measures Modeled at the Watershed Scale