Assessing the Performance of HEC-HMS and SWMM Models for Rainfall -Runoff Simulation for Urban Watershed

Abstract Submission: Understanding the hydrological response of a watershed to rainfall involves comprehending how it translates rainfall into runoff, considering infiltration, surface flow, and groundwater contributions. Simulations of runoff-rainfall are crucial in managing water resources, environmental protection, and infrastructure developments. Several hydrologic models exist from which simulations of runoff-rainfall may be made, but there is a need for an appropriate model that best fits the catchment in question. This research shall focus on simulations of the urban watershed's runoff using two hydrologic models: Hydrologic Modeling System (HEC-HMS), developed by the Hydrologic Engineering Center, and the Storm Water Management Model (SWMM). HEC-HMS is a process-based, deterministic, and distributed model that manages large and intricate watersheds with detailed spatial representation. In contrast, SWMM is a process-based, deterministic, and semi-distributed model that traditionally finds wide application in hydrologic modeling for the urban area. The study area selected is Sugar Creek Watershed, North Carolina. The hydrological and meteorological data obtained from the United States Geological Survey (USGS) are preprocessed using ArcGIS tools to provide input for these hydrological models. In this paper, the performances of the HEC-HMS and SWMM models, against observed streamflow data, are compared in both the calibration and testing phases. The reliability of the concerned models is assessed through several statistical error measures, which include the Nash-Sutcliffe efficiency coefficient, Standard Deviation Ratio, and Root Mean Square Error. The results show the weaknesses and strengths of each model, including an insight into the criteria that water resources engineers need to consider while selecting among hydrological models when simulating rainfall-runoff for any watershed.

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