Quantifying the impact of impervious surface location on flood peak discharge in urban areas

To date, limited attention has been paid to the role of impervious surface (IS) location in influencing flood processes. However, this topic is of tremendous significance for developing guidelines for urban planning and flood management. This study uses the Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS) to investigate the impact of land-use change on flood processes and proposes a new index to quantify the impact of IS location on basin peak discharge. The results indicate that rapid urban expansion in the Longhua Basin, China, has increased peak discharge and flood volume by 140 and 162 % over the past 30 years, respectively. The new index, named the Impervious Surface Impact Index, describes the spatially varying effects of IS increase in individual sub-basins on a basin’s peak discharge. For the Longhua Basin, the index varies from 0.43 in downstream sub-basins to 5.91 in upstream sub-basins. An increase in upstream IS increases peak discharge nearly 14 times more than the same increase in downstream IS. Accordingly, the location of newly created IS can influence flood processes significantly. These findings can help to find suitable locations for urban development while mitigating the impact of land development on flood risks. Copyright Springer Science+Business Media Dordrecht 2015