Field surveys of seven large-scale (greater than one acre) sites in the Houston-Galveston area provided an interesting comparison of design types, criteria, and site characteristics. Two of the sites were primarily fill sites, two were fill and shape sites, two were scrape-down sites, and one was a natural substrate with shore protection.
Frequently inundated organically rich muds seemed to have the most potential for relatively rapid growth and development of vegetation. In contrast, low-organic, dewatered Pleistocene clays at scrape-down sites may take time to become fertile enough for a more rapid spread in vegetation.
Subsidence could be a threat in all areas if rates don’t remain low, but in terms of shoreline stability, all sites had design criteria to guard against erosion.
Both scrape-down and fill sites, plus combinations of the two, have potential for large-scale development. Scrape-down sites are usually developed in uplands so there is the potential of adding wetlands without displacing aquatic habitats, thus expanding wetland habitats in a bay system. In fill sites, vast quantities of dredged material from navigation channels provide a potential source of fill for large-scale development.
The criteria and techniques identified for large-scale marsh development in the Galveston-Trinity bay system have potential for application in other bay-estuary-lagoon systems.