Green Infrastructure in Ameliorating Urban Hydrologic Conditions

Keywords: urban pluvial floods, combined sewer overflows, SWMM hydrologic modeling, green infrastructure, nature-based solutions
Abstract Type: Poster Abstract

Abstract

Urbanization of the Lower Blue River Watershed has increased urban pluvial floods and combined sewer overflows in the Kansas City Metropolitan Area. To ameliorate these conditions, effective watershed management is needed to store stormwater and reduce surface runoff. To this end, installation of green infrastructures may be a viable option. But their utility has yet to be evaluated.

Three sites, from the industrial, business, and residential areas, each measuring ~12 acres, with 55-85% of imperviousness in the Lower Blue River watershed were selected as a pilot study. Due to the unavailability of urban sewer drainage data for the study area in the public domain, we simulated such data using the Virtual Sewer Network Generating Tool (Reyes-Silva et al., 2023). The simulated drainage, together with elevation, daily weather, landuse/landcover, hydrologic soil group, and % of imperviousness data were then imported to the National Stormwater Calculator (USEPA, 2024) and the Storm Water Management Model, SWMM, (Rossman and Simon, 2022) via the QGIS plug-in “generate_swmm_inp” (Schilling and Tränckner, 2022) to model the efficacies of green infrastructures in mitigating urban surface runoff and their costs.

Preliminary results show that while the land-parcel-scale green roof, rain garden, and infiltration basin can increase evaporation and infiltration, the amount of additional surface runoff reduced is about 5.4 to 7.4 % of the rainfall. But installation, maintenance, and life cycle costs range from $1,891 to $622,785.

Under extreme events, broader scale nature-based solutions, such as the creation of wetland, will be needed to effectuate further abatement.