Spring 2020 – Analyzing the impact of fill and floodplain development on flooding in a Houston Watershed

The impact of recent flood events like Hurricane Harvey on coastal communities necessitates an assessment of specialized flood mitigation measures at multiple scales for the possibility of flood damage reduction. Fill is an example of a flood mitigation technique adopted for low-density development in flood-prone suburban communities in the United States and involves the use of dirt, sand or dredged material to elevate properties above flood levels, allowing development to occur in floodplains. Despite applying mitigation measures like fill, the repetitive flood damages recorded in recent times leads to questions on whether structures on fill still incur flood damages after structural flood mitigation. This project addresses the lack of comprehensive knowledge on the impact of fill regulations by using a two-step analysis of hydrology modeling, and a landscape and flood risk model to quantify the difference between fill and non-fill properties in a coastal watershed in the Houston Metropolitan area in Texas. The results in this research will highlight the importance of examining parcel-level flood mitigation policies that have cross-jurisdictional economic and planning implications, and the cumulative effect on flood damages at both the community and regional watershed scale. This research also provides insight into the need for synergistic flood risk reduction and land use policy, as well as incentives to compensate for the use of fill in floodplain land use, development, and planning.