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.
|