Measuring total longshore sediment transport with a LISST instrumented mini-sled.
Huchzermeyer, Erick Karl
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A surf zone sediment transport study was conducted in Jamaica Beach, Texas, using new oceanographic equipment. A mini-sled was constructed and outfitted with an instrument package that consisted of two velocimeters, one current profiler, three OBS's (Optical Back Scatter), and a Sequoia Instruments LISST (Laser in situ Scatteroineter and Transinissoineter). This instrumented sled was used to measure sand concentration and flow velocity across the surf zone. Using these two parameters we were able to determine longshore sand transport. The study provided an accurate measurernent of sand transport on a muddy coast. Previous methods for measuring total longshore sediment transport did not quantify the effect that mud-sized particles would have on OBS's. To circumvent this issue we used the LISST to measure sand concentration in the water. The LISST can measure sand concentration despite the presence of mud. During this study it appeared that sand transport peaks 10 cm above the sea bottom. The measured total longshore transport rate closely matched results from one equation for determining total longshore transport (Kamphius, 199 1). The CERC equation was also compared to the measured result.