A framework for flood risk assessment under nonstationary conditions or in the absence of historical data

Abstract

We present a diagnostic framework to assess changes in flood risk across multiple scales in a river network, under nonstationary conditions or in the absence of historical hydro-meteorological data. The framework combines calibration-free hydrological and hydraulic models with urban development information to demonstrate altered flood risk. Our models utilize hydraulic geometric data and high-resolution remote-sensing information provided on a nearly global basis. The need for calibration is eliminated because model parameters are directly related to the physical properties of the system. We apply the methodology in a case study for Mecklenburg County, NC, in which we assess the effects of land cover changes on flood frequency. We obtained maps of expected inundated zones under different conditions of land cover and storm return periods and compared them with the 100-year return period inundation maps developed by Federal Emergency Management Agency that are based on more complex hydraulic models. The close agreement supports our framework’s applicability and generality.