Effects of Proposed Closure of Southwest Pass on the Regimen of Vermillion Bay, Louisiana: Hydraulic Model Investigation
Abstract
Use of Vermilion Bay to relieve the shortage of 1rater for rice irrigation in southwest Louisiana has been proposed, but will require some means of reducing salinities in the bay during the irrigation season. Closure of Southwest Pass, which connects Vermilion Bay with the Gulf of Mexico, was proposed as a means of retarding salt-water flow into the bay, and a model study to investigate the proposal was initiated. Before the effectiveness of this plan could be determined for conditions which will obtain in the future, the effect on bay salinities of a reduction in fresh-water inflow as a result of the Old River Control Structure being constructed on the principal fresh-water source, the Atchafalaya River, had to be ascertained. The model, built to scale ratios of 1:100 vertically and 1:2000 horizontally, reproduced 1860 square miles of the problem area, and included devices for simulating tides, tidal currents, salt-water movement, alongshore currents, fresh-water discharge, and fresh-water withdrawal. The model tests showed that installation of the proposed closure of Southwest Pass under present conditions of Atchafalaya River discharge would reduce maximum salinities along the west side of Vermilion Bay to a maximum of 1700 ppm for a season of normal runoff and a maximum of 3600 ppm for a season of extremely low runoff. Corresponding maxima for present conditions with Southwest Pass open are in the order of 8000 p:pm and 8800 ppm, respectively. The tests also showed that, in addition to a major reduction in maximum salinities for conditions of both normal and low runoff, closure of Southwest Pass would retard the time of maximum salinity along the west side of Vermilion Bay so that maximum salinity would occur well after the peak of the irrigation season.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1959
- Accession Number
- ADA637646
Entities
People
- Thomas J. Kinzer Jr.