Preservation of Estuaries by Tidal Inlets

A basic proposition of the Texas Water Plan is to use gulf waters as much as possible to preserve bay and estuary environments, thereby minimizing needs for fresh water. The complex problems involved in the design and building of balanced tidal inlets to allow free inflow of adequate gulf water are reviewed from the standpoint of coastal engineering and tidal hydraulics. Environmental controls include use of inlets to both increase and decrease salinity, aid circulation and mixing of the waters, and provide sufficient tidal flushing to help the estuary assimilate treated return flows. Concepts of typical inlet design, including the sediment transport aspects, water and salinity balance, and tidal flushing process, are presented. Misuse of imbalanced inlets is demonstrated by extreme values of tractive force. The astonishing magnitude of value of these estuaries for recreation, and sport and commercial fishing clearly establishes the necessity to save these aspects of the bays and estuaries. Reason dictates that scientific use must be made of balanced tidal inlets along this coast.