Washington County Inland Flooding Vulnerability Assessment

Washington County, Florida

Michael Baker is performing a vulnerability assessment for Washington County, Florida, consisting of an inland flood study to evaluate impacts on the client’s assets and the potential impact of climate change on lake stages in the Sandhill Lakes Region. Tasks include a county-wide asset inventory of critical infrastructure, stakeholder coordination, flood modeling and a final vulnerability assessment report.

Pronounced flooding has affected residents across northwest Florida following Hurricane Michael in 2018. Southern Washington County is within a karst region characterized by sinkholes, springs and sinkhole lakes. Many lakes are internally drained, with no surface water outlet. Above-average rainfall has refilled underlying aquifers and increased groundwater levels, causing flooding. Downed vegetation has blocked river and creek channels, extending flooding beyond normal floodplains.

The team is identifying the client’s critical assets through evaluation of GIS databases, public resources, interviews and field reviews. The client has little to no digital record of assets, so this is an extensive effort. Michael Baker is tabulating and locating these assets on the map deliverables, providing significant modernization of records.

We are implementing an interactive surface-groundwater modeling approach estimating groundwater seepage and aquifer connectivity for the land-locked basin areas. The team is appraising a total of nine future condition scenarios for each baseline condition. Because the Choctawhatchee River is directly connected through Choctawatchee Bay with the Gulf of Mexico, the team is assessing sea level rise elevations to determine its potential impact on the Choctawhatchee River and nearby communities. These effects are evaluated for the 25- and 50-year planning horizons to determine their impacts on client assets.

Michael Baker is assisting with the identification of a prioritized list of projects to address the vulnerabilities revealed by the assessment. As a result, the client will be positioned to apply for Resilient Florida infrastructure grant funding to address identified needs.