Hydraulic Study of Multiple Inlet System: East Matagorda Bay, Texas

Abstract

The hydrodynamic feasibility of a proposed third inlet to East Matagorda Bay, Texas, was examined by application of a two-dimensional, depth-averaged hydrodynamic model. Wind-driven flows in this remote, shallow bay frequently dominate the weak astronomical tide. The bay presently has two connections to the Gulf of Mexico, one through a short flood-relief channel and the other through a long and circuitous navigation channel. The study had to consider whether installation of a third inlet would cause the relief channel to close or increase the already strong current velocity in the navigation channel that is a concern for boating safety. The model was calibrated with measurements of wind, water level, and current taken in this study. It is concluded that the new inlet will be ebb-dominated because of the wind-induced current, and that the relief channel will not close in the presence of the new inlet. In addition, the peak current at a critical maneuvering area in the navigation channel that presently poses a hazard to vessel traffic will be reduced by as much as 25% as a result of opening the new inlet.