Long-Term Inlet Stability of a Multiple Inlet System, Pass Cavallo, Texas

Matagorda Bay, Texas, is connected to the Gulf of Mexico by two inlets, Pass Cavallo and the Matagorda Ship Channel (MSC). Pass Cavallo is a natural inlet located at the southwest terminus of Matagorda Peninsula, and the MS C is an artificially cut, deep-draft federally maintained navigation channel approximately 7.2 km northeast. Pass Cavallo was historically stable until the 20^th century, when the tidal prism was first reduced in 1935 by division of Matagorda Bay due to deltaic progradation of the Colorado River, and later in 1966 as a result of the construction of the Matagorda Ship Channel. In response to these reductions in tidal prism, the entrance width at Pass Cavallo reached historical minimums as Matagorda Peninsula and Matagorda Island prograded into the inlet. Long-term stability and potential of possible closure of Pass Cavallo are evaluated through theoretical and empirical relationships, and long-term analysis of morphologic change.