Capitalizing on Alluvial Processes to Gradually Establish Islands and Wetlands in Urban Harbors

Abstract

This project proposes a strategy for capitalizing on dredged alluvial sediment to create developable islands and wetlands over time. Estuary environments, where rivers merge in a harbor with the open sea, are dynamic locations influenced by tides and alluvial flow. Urban centers located in estuaries utilize the intersecting waterways for shipping and recreation. In order to accommodate the needs of shipping in these areas, channels are dredged in the harbor to allow ships to safely navigate. The sediment dredged from the harbor is then placed in spoil zones outside of the shipping lanes and away from harbor traffic. This dredging process is continuously repeated as river sediments are carried into the harbor. Instead of discarding the dredged material, it can be utilized, along with capturing river sediment, to initiate the growth of islands and wetlands and create developable land for the city. Wetland flora and fauna will establish communities where the dredged material will be impounded by a system of dikes and culverts. The impounded islands will be flanked by a series of groins capturing sediment flowing past the island, allowing it to expand outward. The site chosen to test this proposal is Charleston Harbor in Charleston, SC. The harbor is used for commercial and naval shipping and is also home to several important civil war monuments that draw tourism to the city. The architecture proposed for these emergent islands will support harbor tourism with a visitor center, environmental educational facilities, and recreational trails and piers for public use.