Flooding Analysis and Resiliency Improvement Planning Across Diverse Watershed Characteristics
As part of the City of Fayetteville NC City-wide Watershed Master Plan program, existing flooding characteristics and potential flood mitigation projects are being evaluated across watersheds with many diverse characteristics. Watersheds within the City vary substantially with regard to land use and development intensity, as well as natural and constructed drainage infrastructure characteristics. For example, the Beaver Creek 3 watershed predominantly consists of single-family residential land use and contains drainage infrastructure frequently alternating between closed pipes and open channels, all of which drain to a relatively small unnamed tributary to Beaver Creek. Elsewhere in the City, the Cross Creek watershed spans residential, commercial, industrial, and institutional land uses with development intensities ranging from largely open areas in the upper parts of the watershed to the intensely developed downtown area in the lower watershed. This variability poses unique considerations with regards to modeling and analysis approach to ensure appropriate stormwater conveyance details are captured and results can be compared across these diverse watersheds. The Cross Creek watershed has a history of flooding concerns associated with larger hurricanes in recent years and more frequent thunderstorms. Flooding concerns are especially challenging in the downtown area, due in part to channel geometry associated with a historic mill pond. Analysis of this watershed through the use of HEC-HMS, a 2D HEC-RAS model, and a 2D Infoworks ICM model allowed for the consideration of dynamic interactions between the creek system and tributary pipe networks. This analysis approach also supported the consideration of large-scale improvements through the downtown area, where proposed solutions are affected by a myriad of urban constraints and challenging hydrologic and hydraulic characteristics. This presentation will provide an overview of watershed characteristics encountered across the study area, how those diverse characteristics were considered in the analysis approach, their impact on analysis results, and how findings from these watershed master planning efforts could inform similar analyses for other localities.Author Bio
Laura Gill works within Hazen and Sawyer’s stormwater practice group in Raleigh, NC. Ms. Gill focuses on planning, design, and implementation of green infrastructure and traditional stormwater management efforts to meet regulatory drivers while providing water quality, flood relief, and community benefits. She has partnered with the City of Fayetteville on stormwater master planning, impoundment analysis, and detailed stormwater design efforts.
