Estimating the contribution of vacant land in mitigating flooding in the Neuse Basin

Sarah Lebu , Rita Gyimah , Christopher Samoray

Flooding in the United States results in economic losses amounting to tens of billions of dollars annually, with urbanization and development in floodplains serving as key drivers of increased flood risk. This study explores the flood retention potential of vacant lands within current and projected landcover scenarios in the Neuse River Basin, a rapidly urbanizing region prone to significant flooding challenges. Using InVEST, a GIS-based modeling suite for ecosystem service valuation, we integrated land use/land cover (LULC) data with hydrological modeling to quantify flood mitigation capacity. Our findings indicate an 8.1% increase in floodplain land development from 2020 to 2060, with an additional 10% rise projected from 2060 to 2100. Despite these trends, vacant floodplain land parcels demonstrate significant potential for floodwater retention, with a one-square-foot increase in vacant land corresponding to a 1.65 m³ rise in runoff retention capacity. Results underscore the sensitivity of flood storage capacity to landcover changes and highlight the importance of preserving vacant lands in floodplain management. The results also point to the importance of river basin management plans running parallel with local development policies. This study offers a practical framework for assessing ecosystem-based flood mitigation services and provides actionable insights for urban planners and policymakers.