Identifying Priorities for Urban Parameterizations in the WRF-Hydro Framework

Forecasting floods in an urban landscape is central issue for many regions in the world which are experiencing an increase in imperviousness from urbanization and population growth in cities, as well as changes in climate. Urban infrastructure – e.g. detention ponds, storm drainage networks –contribute to complex routing in an urban environment, making it difficult to use more traditional parameterizations of land use and landscape variables to predict flood locations and timing, even with sophisticated modeling systems.  This project aims to improve representation of short-term flood forecasts in an urban area for the new National Oceanic and Atmospheric Administration/National Weather Service National Water Model, which utilizes the WRF-Hydro modeling framework to develop forecasts over the conterminous United States.  We focus on a small, highly urbanized catchment in Denver to run experiments testing three urban-specific changes: (1) increasing the terrain and channel routing resolution, (2) updating and customizing the land use (i.e. imperviousness), and (3) representing detention ponds. We compare results from these experiments with observed streamflow and the results from the coarser National Water Model configuration to determine the priorities for urban parameterizations.