Water First
Planning for where water is and is going to be
Many communities throughout Charleston are already struggling with the adverse effects of regular and severe flooding. With sea level rise and climate change, it is important that we plan not only to improve existing challenges with flooding, but to prepare for future challenges. This post provides an overview of the Land & Water Analysis completed by Waggonner & Ball, the Water Institute of the Gulf, Robinson Design Engineers and Surculus Design.
The City Plan will guide development and planning decisions for the next 10 years, primarily through recommendations for land use (inhabitation) and guiding priority investments for improved drainage and transportation networks (infrastructure).
The piece we were missing was the Land and Water Analysis. which provides a technical understanding of the relationship between Charleston’s landscape and its current and future flooding challenges related to sea level rise and climate change. The analysis is rooted in the same principles as those in the Dutch Dialogues™ report and serves as the foundation for all aspects of the Charleston City Plan.
the analytical approach
A variety of factors formed the basis of the Land & Water analysis.
Water
Rain
Tides
Floodplain
Storm Surge
Sea Level Rise
land
Elevation
Land cover (ex: trees and pavement)
Development
Ecology
Soils
From these factors, all areas of the city were categorized by 3 overlapping and intersecting considerations:
Elevation Zones - What is your risk?
Watershed Sensitivity - How do you impact your surroundings?
Environmental sensitivity - What other ecological considerations need to be taken into account?
timeline
The timeline of this analysis is based on a 50-year (2030-2080) intermediate sea level rise scenario.
In this scenario, sea level is expected to rise by approximately 3 feet by 2080, and 3.6 inches in the next 10 years. A tide above 7 feet in Charleston typically means water begins spilling into roadways, inundating storm drains and sometimes flooding structures at lower elevations. In the intermediate sea level rise scenario, 7-foot tides will become the average daily high tide by 2040.
This scenario is the same as that for Charleston’s Sea Level Rise Strategy.
results
elevation risk zones
Scroll down to view a map of the city by elevation risk zones and read more about what to expect for each zone.
watershed and environmental sensitivity
Though low-lying areas are certainly more vulnerable to tidal flooding and storm surge; other site-specific conditions can contribute to the intensity, frequency and impact of flooding. These site-specific conditions such as watershed type, soils and vegetation, infrastructure and vulnerability should inform which combination of planning strategies to apply where - to reduce impacts of flooding and sea level rise and increase resilience.
want to dive deeper?
This is just a small selection from the 294-page Land & Water Analysis report.
For the full report: Click here. (It is a large file and may take awhile to load).
To watch a presentation of the report: Click here (starts at 1:47:02).
To learn more about flooding, tides and current efforts, check out these resources from Charleston’s GIS (Geographic Information Systems) Team:
Living With Water: City of Charleston Map History Tour
How High is that Seawall? Understanding Elevation and Tides in Charleston
We also recommend checking out the Rising Water series published by the Post & Courier News. Read their Rising Water series here.