Mean High Water (MHW) is a project documenting the impacts of sea level rise & flooding in and beyond the South Carolina Lowcountry. The title is in reference to the MHW tidal datum defined and maintained by the NOAA Center for Operational Oceanographic Products and Service.
The tides of Charleston Harbor and the Atlantic Ocean are increasingly encroaching into the natural and built environment of Charleston and the Lowcountry. The rate of increase in the number of coastal flood events is alarming. Approximately 53.3% of all coastal floods observed in Charleston Harbor from 1921 through 2022 have occurred since 2010. An average of 18.8 coastal floods occurred per year in the 1990s. In the 2010s, the annual average was 42.4 coastal floods2, an increase of over 200%.
MHW was started in 2020 by photographer and engineer Jared Bramblett. This is intended to be an evolving and collaborative documentation of the impacts of flooding. If you are interested in participating, please reach out.
All thoughts and opinions presented on this site are solely those of the author and are not necessarily those of any other organization.
All content presented on this site is copyrighted. To inquire about content usage, please submit a request.
Charleston Harbor, Cooper River Entrance1
Coastal Floods (>7-ft MLLW)2
Major Coastal Floods (>8-ft MLLW)2
Peak Tide Crests (ft, MLLW)3 Statistics current as of 08/31/2023
Sea Level Rise Trend (1901-2022)1
Sea level trend of 1.13-ft per 100 years (1901-2022)
1 Tidal Benchmark Station - Charleston, Cooper River Entrance, SC - Station ID: 8665530
2 NWS Coastal Flood Event Database
3 Advanced Hydrologic Predictions Service, Charleston, SC
Why does Charleston flood, and why does it matter?
A map and discussion to help you understand how flood risk accross the Charleston Peninsula relates to the predicted tide levels.
This is a database maintained by the National Weather Service Charleston that tracks coastal flooding in Charleston and Savannah. It is referenced often throughout this site, particularly when discussing the number of coastal floods that have occurred in Charleston Harbor.
This is the homepage for the Charleston Tidal Benchmark, which serves as the main tide gauge referenced for tide levels in the Charleston region. The tidal datums (e.g. MLLW, MHW, MHHW) for Charleston are presented here. Lunar tide levels predictions can be found here, and the database of historic tide levels can be accessed here.
This map, available through the Preservation Society of Charleston, shows “the original high water lines, fortifications, burroughs, great fires, historic information, etc.” This is a great reference to understand where the old creeks used to existing on the peninsula, and thus, where there is a greater flood risk today.
The City of Charleston Flooding and Sea Level Rise Strategy update for 2023 builds upon the 2019 and 2015 Strategies, including important and updated climate data, as well as infrastructure and drainage project and policy updates.
These maps and tools have been developed by the City to help citizens monitor different types of flooding.
This is a City GIS product that is similar to and references the NWS Coastal Flood Event Database, but it has more interactive features and flooding statistics.
This is another City produced GIS web application that provide real time tide, rainfall, and street closure data. This is an incredibly useful tool if you are trying to navigate the City during a flood. I recomment bookmarking this on your phones homes screen so that you always have quick access to it.