Accession Number : ADA483132

Title :   Limiting Slopes and Depths at Ebb-Tidal Shoals

Descriptive Note : Journal article

Corporate Author : ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB

Personal Author(s) : Buonaiuto, Frank S. ; Kraus, Nicholas C.

Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD= ADA483132

Report Date : 2003

Pagination or Media Count : 16

Abstract : Dense bathymetry surveys obtained by LIDAR at 13 small to medium coastal inlets of the continental United States were analyzed to quantify limiting (maximum) bottom slopes of ebb shoals and entrance channels. The LIDAR data were supplemented with conventional bathymetry measurements from five large inlets to obtain predictive relationships for the limiting (minimum) depth over crest of the ebb shoal. The sites, all located on sandy coasts, were chosen to cover a range in tidal amplitude, tidal prism, and average annual wave height. Wave-dominated inlets exhibited steeper slopes on their seaward margins than tide-dominated inlets. Slopes on ebb shoals typically do not exceed 4-6 deg, with seaward slopes being 1-2 deg steeper than landward slopes. Dredged entrance channels have steeper slopes than natural channels, with maximum slopes immediately after dredging reaching 6-8 deg. At one inlet having a series of LIDAR surveys, entrance channel maintenance dredging created 3-5 deg side slopes that decreased 0.5-1 deg/year for the next 2 years to achieve a typical slope of 3 deg along much of the channel. Greatest bottom slopes are found in scour holes near jetties (10-12 deg) and at the entrance bars (8-10 deg) of (tideless) Great Lakes harbors. Limiting depth over crest of the ebb shoals is predicted well by the parameter HSP(exp 1/4), where HS is the average annual significant wave height, and P is the spring tidal prism. High correlation was also found between limiting depth and prism, and with limiting depth and wave height.

Descriptors :   *SLOPE , *INLETS(WATERWAYS) , *DEPTH , BATHYMETRY , TIDES , GEOMORPHOLOGY , CHANNELS(WATERWAYS) , REPRINTS , OPTICAL RADAR

Subject Categories : PHYSICAL AND DYNAMIC OCEANOGRAPHY
      HYDROLOGY, LIMNOLOGY AND POTAMOLOGY

Distribution Statement : APPROVED FOR PUBLIC RELEASE