How does floodplain geomorphic heterogeneity influence flood routing and attenuation?

Floodplains can temporarily store floodwaters and attenuate floods, reducing downstream impacts. This study tests how topographic variability, or geomorphic heterogeneity (GH), of floodplains influences flood routing. For two sites that differed in floodplain characteristics and overall gradient, flood simulations were performed in a 2D hydrodynamic model. For each site, flood hydraulics were compared between the natural floodplain and for a scenario in which the floodplain was artificially flattened. Results showed that floodplain GH may not always attenuate downstream peak flood discharge but has a stronger potential to mitigate fluvial erosion hazards by reducing stream power.