Evaluating the Restoration Potential of An Urban Salt Marsh with GIS and Hydrological Modeling

Denise Burchsted, Paul K. Barten, and C. Dana Tomlin

Salt marsh restoration alternatives were evaluated for the West River WWI Memorial Park in New Haven, Connecticut. Ecological disturbance of the site peaked in the early 20th century with the installation of tide gates, dredging of a channel and reflecting pool, and placement of dredge spoil and sand fill to create upland habitat. This converted an extensive salt (Spartina) marsh to a mixture of freshwater and upland communities. Subsequent invasion by common reed (Phragmites australis) sparked community interest in restoring salt marsh vegetation. A digital terrain model was created, based on topographic data from a 1992 survey, to provide the foundation for hydrologic analyses of restoration alternatives. Using water level, discharge, and salinity data collected during experimental tide gate openings in 1992, we modeled tidal fluctuations for several restoration scenarios. Opening one tide gate, without altering current topography, could potentially restore salt marsh vegetation on only 2.6 hectares (4.5% of the site). Opening two tide gates would slightly increase restoration potential to 3.4 ha (6%). A much greater conversion could be achieved by altering the microtopography. For example, moving approximately 71,000 m3 of material based on a landscape architect’s preliminary design and opening two tide gates could restore up to 17.0 ha (30%). The results should help the neighboring community, government officials, landscape architects, and environmental scientists to devise a restoration strategy.



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