Indian River Inlet: An Evaluation by the Committee on Tidal Hydraulics
Abstract
Indian River Inlet, Delaware, has experienced progressive scour since about 1940, and the scour has accelerated since 1970. The U.S. Army Corps of Engineers Committee on Tidal Hydraulics reviewed the inlet's history, examined its processes, and provided recommendations on needed remedial measures to the U.S. Army Engineer District, Philadelphia. The inlet, originally less than 20 ft deep, deepened at a rate of about 0.5 ft per year, on average, from 1940 to about 1970. From 1975 on, the rate increased to 1 ft per year, and by 1992 it was deeper than 40 ft everywhere, with some holes more than 100 ft deep. During the period, the north jetty had suffered damage, sand bypassing had begun, and numerous highway bridge piers were removed. Analyses showed that the inlet was far from an equilibrium size with respect to the O'Brien-Jarrett curve and the balance between sand supply and transport through the inlet. Analysis of sand transport rates and clay erosion rates suggested that a stable inlet might result at an average depth of about 60 ft. The more rapid recent rate of erosion was linked to several potential factors, of which exposure of clay sediment layers is the most probable. Remedial measures using structures or bed armoring were not recommended at present. Instead, continued monitoring of the inlet and jetties was recommended.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1994
- Accession Number
- ADA283317