Flood Risk Mapping From Orbital Remote Sensing

Abstract

Standardized methods for flood risk evaluation in the United States were developed by the United States Geological Survey over more than a century [Klingeman, 2005; Wahl et al., 1995]. They use an extensive network of river gauging stations and associated time series of annual flood peak discharge; many of these extend for 50–100 years. To meet regulatory and insurance requirements, flood risk assessments must be not only objective and scientifically defensible, but also uniformly applicable across highly variable hydrological regimes. The results are commonly subject to legal challenges as property owners contest the level of risk assigned; consistency of method is thus critical. Through these standard methods, risk is modeled: a flood discharge of particular calculated recurrence interval is routed through the channel and across the landscape via regulatory agency‐approved hydrodynamic models such as HEC‐RAS [FEMA, 2002]. Many developed nations outside the United States have similar risk evaluation methodologies. Quite commonly, a “100‐year” discharge and associated floodplain are defined: this floodplain is the land area along a river where, at its margins, a 1% annual exceedance probability is calculated for inundation by floodwater (interior por­ tions may experience much higher inundation frequencies). Thus, the probability Pe that one or more floods occurring Dartmouth Flood Observatory CSDMS/INSTAAR, University of Colorado, Boulder, Colorado, USA ABSTRACT