Spatial targeting of nature-based solutions for flood risk management within river catchments

A wide range of nature-based solutions for flood hazard management work by storing and slowing flow within catchments, and therefore, there is a need to identify the optimal locations for implementing these solutions. This paper presents a relative scoring-based mapping of the likely locations that contribute to the flood peak. Targeting flow reduction and attenuating mitigation actions in these locations can be an effective way to reduce flood damages at impact points downstream. The presented tool, SCIMAP-Flood, uses information on land cover, hydrological connectivity, flood generating rainfall patterns and hydrological travel time distributions to impacted communities to find the potential source areas of flood waters. The importance of each location in the catchment is weighted based on its contribution to the flood hazard at each of the downstream impact points. In the example application, SCIMAP-Flood is applied at a 5-m grid resolution for the River Eden catchment, Cumbria, England, to provide sub-field scale information at the landscape extent. Therefore, the tool can identify sub-catchments where more detailed work can test different mitigation measures.