Sea Level Rise and the Hillsborough River

March 2019 – The latest National Oceanographic and Atmospheric Association’s (NOAA) Sea Level Rise projections suggest that if just the intermediate projections are correct, we could see three feet of sea level rise by 2100 (Global and Regional Sea Level Rise Scenarios for the United States, NOAA Technical Report NOS CO-OPS 083, January 2017). This could have significant consequences for both the built and natural environment.

While much focus is typically on our coastal shorelines, Ms. Libby Carnahan of Florida Sea Grant and the University of Florida IFAS Extension, gave a presentation to the River Board’s Technical Advisory Council on January 15 on how sea level rise will affect the Hillsborough River. She noted how the lower river is extensively developed, and in many areas, shoreline vegetation would not have an opportunity to migrate to higher elevations due to this development. Shoreline parks would be impacted first at high tides, as they exist at lower elevations than many built properties along the river.

This is consistent with recent work by the Planning Commission on the City of Tampa‘s Sea Level Rise Vulnerability Assessment. As sea levels continue to rise this century, roads and buildings at low elevations will begin to experience flooding events. Much of our area’s coastal storm drainage system was constructed based on a previous lower sea level than today and did not assume this level to rise in the future. With rising sea levels, coastal storm drainage systems become less effective, leading to increased flooding events with longer durations. Saline and brackish water may push itself further up the Hillsborough River.

Hillsborough County is currently preparing a Community Vulnerability Study that will identify the risks associated with sea level rise and ways we can address these issues. The work that is being done by the Planning Commission, Estuary Program, and City and County governments will help to find solution and mitigation projects to address the impacts of sea level rise.

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