FIELD INVESTIGATION OF SUSPENDED SEDIMENT IN THE SURF ZONE

Abstract

Purpose - This paper presents the results of a number of field observations made at Pacific Beach near San Diego, California with a suspended sediment sampler. A detailed description of the laboratory and field development of the sampler is presented in the Beach Erosion Board Technical Memorandum Ho. 3k entitled "Development and Field Tests of a Sampler for Suspended Sediment in Wave Action". The laboratory development involved: a circulating system which provided various current velocities and concentration patterns at the test section; the testing of various size nozzles; the study of particle size distribution of samples obtained by the nozzles; and the development of correction factors for field conditions. It was concluded from the laboratory study that a pump-type sampler could be adapted to the study of suspended material movement in wave action. The principal result from the laboratory tests was a tentative finding that by pumping through a vertically disposed 1/2-inch nozzle with a velocity approximately twice the maximum orbital current velocity in a wave, samples could be obtained which were representative in weight (even without a correction factor) to within about 15 per cent of the true suspension.