Charleston County Drainage Analysis & Water Flow Map

Address
Overview

Where does rainwater drain in Charleston County? This interactive map shows surface drainage patterns across Charleston, Mount Pleasant, North Charleston, and surrounding areas based on terrain shape - where gravity directs rainwater based on elevation and slope. For official flood risk information, see the FEMA flood zone layer on the Hazards tab.

Charleston County's peninsula geography means drainage is constrained by tidal rivers on three sides - the Ashley, Cooper, and Wando. During high tide, gravity-fed drainage outfalls are blocked, trapping rainwater on the surface. The county experiences over 80 tidal flood days per year, a number that has tripled since 2000 due to sea level rise. Enter any address to see parcel-level surface drainage analysis and water flow direction based on terrain shape.

Interpretation

Select a location on the map or enter an address to see terrain analysis.

3D Terrain Visualization
Where does rainwater flow based on terrain shape? Blue areas show where water collects and drains downhill.
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4.0× Horizontal:Vertical
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