MEAN HIGH WATER


A project documenting
Sea Level Rise & Flooding
in the South Carolina Lowcountry



01 OVERVIEW ︎︎︎
02 LATEST ︎︎︎   
03 ARCHIVE ︎︎︎
04 RESOURCES ︎︎︎

ABOUT
Mean High Water (MHW) is a project documenting the impacts of sea level rise 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 45% of all coastal floods observed in Charleston Harbor from 1953 through 2020 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%.

This project was started by photographer and engineer Jared Bramblett in 2020. It is intended to be an evolving and collaborative documentation of the impacts of rising seas and how communities are adapting to them. If you are interested in participating and submitting to the project, please reach out. All content on this site is copyrighted. If you are interested in using any content, please submit a request.


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CONTACT 
Jared Bramblett
jaredbramblett@gmail.com

All thoughts and opinions presented on this site are solely those of the author and are not necessarily those of any other organizations.

RECORDS & STATISTICS
Charleston Harbor, Cooper River Entrance1

Coastal Floods (>7-ft MLLW)2
1.
2.
3.
4.
5.
89 (2019)
68 (2020)
58 (2015)
55 (2016)
46 (2017)

Major Coastal Floods (>8-ft MLLW)2
1.
2.
3.
4.
5.
7 (2020)
6 (2015)
4 (2019)
3 (2018)
2 (2009, 1947)

Peak Tide Crests (MLLW)3
1.
2.
3.
4.
5.
09/22/1989 - 12.52-ft (Hugo)
08/11/1940 - 10.23-ft (Unnamed)
09/11/2017 - 9.92-ft (Irma)
10/08/2016 - 9.29 (Matthew)
01/01/1987 - 8.81-ft 

22 of the 36 (61%) major flood tides on record have occurred since 2015.3

Statistics current as of 8/31/2021

REFERENCES

1Tidal Benchmark Station - Charleston, Cooper River Entrance, SC - Station ID: 8665530
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.

2NWS Coastal Flood Event Database
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.

3Advanced Hydrologic Prediction Service, Charleston, SC
Forecasts for water levels at the tidal bench mark based on meteorological predictions are presented here.

Reviewing Flooding from January through March 2021

21 APRIL 2021 - Jared Bramblett
Stormwater flooding on Line Street in the Westside Community.

So far, it’s been a relatively quiet year for flooding in the Charleston area. As of April 20th, there have been seven (7) tides that have exceeded the tidal flooding threshold (MLLW = 7-feet), with five (5) of them occurring in January and two (2) of them in March. Of the seven (7) flood tides, the highest was peaked at 7.23-feet MLLW on March 3rd, which is classified as a minor flood. That’s not entirely surprising, as January, February, & March have historically averaged the 3rd, 2nd, and 1st lowest number of flood tides. As the chart below shows, the first quarter of 2021 was tide the fourth highest number of tidal floods we’ve seen in Charleston Harbor.



We also saw an intense rainfall on the afternoon of March 18th that resulted in flooding across the area, particularly across the Charleston Peninsula. Officially, a record daily maximum rainfall of 2.16-inches was recorded at Waterfront Park, breaking the old record of 1.83-inches set in 1969. The photos below are from the Westside and North Central areas of the peninsula. The floods resulting from this rainfall were not as bad as the ones we saw in September of 2020, and as Sarah Williams pointed out in an Instagram comment, it was first stormwater flooding event in six (6) months.





© 2021