Accession Number : ADA019936

Title :   Techniques in Evaluating Suitability of Borrow Material for Beach Nourishment.

Descriptive Note : Technical memo.,


Personal Author(s) : James,William R.

Report Date : DEC 1975

Pagination or Media Count : 82

Abstract : Selection of borrow material for use in beach restoration and periodic nourishment requires analysis of the textural differences between the potential borrow and native beach materials. Three quantitative techniques proposed for such analysis are reviewed and compared, and guidelines are suggested for use in planning and designing projects requiring beach nourishment. The techniques are of two types. One is based on the assumption that sorting processes will selectively remove borrow material from the various size classes until a 'stable grain-size distribution' (gsd) is obtained and the placed fill stabilized. The gsd of the native material is used to predict the character of the stable gsd. Methods of this type lead to calculation of a 'fill factor,' an estimate of volume of borrow material required to produce a unit volume of stable beach material. Examination of the conceptual basis for each method suggests that the SPM method may overestimate fill factors whereas Dean's method may underestimate them. A modification in the assumptions underlying the SPM method results in an approach which appears to represent a satisfactory compromise between these alternatives. Another type of technique was proposed by James (1974). It is based on the assumption that no material is absolutely stable, but that erosion rates depend in part on the gsd of the material exposed to existing coastal processes. Prediction of erosion rates associated with a given borrow material is based on observation of erosion rates and textural properties associated with native materials.

Descriptors :   *Beach erosion, *Replenishment, Tides, Erosion resistance, Grain size, Sand, Texture, Control, Hurricanes, Protection, Coastal regions, Stability, Stabilization systems, Selection, Sorting, Distribution, Rates, Exposure(General), Losses, Computations, Civil engineering, Military engineering, Fillers, Filling, Materials, Material separation, Methodology, Feasibility studies, Assessment

Subject Categories : Geology, Geochemistry and Mineralogy
      Civil Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE