Design of sustainable tidal creeks for beneficial use (created) marshes in Galveston Bay

A project is currently underway to create marshes in Galveston Bay using dredged materials. Two hundred acre earthen boxes (cells) were built in various locations in the bay and dredged materials were pumped in. In this paper we report on our efforts to design tidal creeks for two adjacent cells, north of Bolivar Peninsula. The creeks will be cut once the marsh has settled to the design elevation. The goal of our design project was to design sustainable tidal creeks. The velocities needed to be sufficiently high in order to prevent siltation of the creeks. The creeks velocities must not be too high in order to prevent excessive erosion. In order to have a solid basis for the design, a similarly-sized natural reference marsh was selected. A circulation and sediment transport model was developed and tested on the natural marsh. Both models were calibrated with field measurements. The models were later adapted for use in the created (beneficial use) marsh. A critical part of the adaptation was to account for any difference in erodibility in the natural marsh and in the created (beneficial use) marsh. The sediments in the natural marsh and in the created marsh were tested with an in situ flume. They were also compared based on geotechnical data. Interestingly, both the flume measurements and the geotechnical data indicated that the sediments in the created marsh were comparable to the sediments in the natural marsh. This led us to design the tidal creeks in the created marsh with about the same range of velocities as those in the natural marsh.