Longshore Sediment Transport Rate Measured by Short-Term Impoundment

Abstract

The total longshore sediment transport rate in the surf zone was measured at a temporary groin installed at Indian Rocks Beach, west central Florida. Approximate mass balance between updrift accumulation and downdrift erosion, which served as an indicator of reliability, was obtained in four of the six runs, which were subjected to further analysis. Magnitudes of three of the four transport rates were considerably lower than predictions by the Coastal Engineering Research Center formula calculated based on contemporaneous measurements of the breaking waves. Error analysis indicated that the determination of the longshore wave-energy flux factor carried a 22-48% maximum uncertainty, and the measured volume-change rate carried a 22-43% uncertainty. The combined uncertainties produce a 40-90% maximum uncertainty in determination of the empirical transport coefficient K appearing in the Coastal Engineering Research Center formula. Comparable or greater uncertainty in K-values probably exists in the total database available for calibrating predictive formulas. The range in values of K in these measurements cannot be explained by measurement error or uncertainty. Therefore, it is concluded that K is not a constant and that other factors may enter, such as breaker type, turbulence intensity, and threshold for sediment transport.

Coastal geomorphology into the twenty-first century

“…The value of this paper is not only that it successfully links scale, but it also illustrates how longshore sediment transport models can be used to understand coastal morphology and evolution rather than simply be used for engineering applications. This paper differs from most publications on longshore sediment transport, which tend to focus on improved derivations of transport formulae (Wang et al, 1998(Wang et al, , 2002Wang and Kraus, 1999;Schoonees, 2000;Van Wellen et al, 2000;Jena et al, 2001;Kumar et al, 2003) although Pilkey and Cooper (2002) offer an alternative view on this subject. Anthony (2002) discussed the relationship between marine sediment supply and coastal sediment accumulation and how differences along the northern French coast can be explained using these relationships.…”

Measurement of Longshore Sediment Transport Rates in the Surf Zone on Galveston Island, Texas

“…Longshore sediment transport rates obtained with the tracer and long-term impoundment techniques, generally in the range of 100,000-400,000 m 3 /y (KOMAR, 1998), are four to 10 times greater than those rates obtained through short-term impoundment and with streamer sediment traps (WANG and KRAUS, 1999). WANG and KRAUS (1999) attribute the lower rates to the relatively short time period over which the latter type of measurements are made. Another important factor is that techniques such as impoundment and tracers measure both bedload and suspended load, whereas others (e.g., streamer traps) quantify only suspended load.…”

A method to estimate the longshore sediment transport at ebb‐tidal deltas based on their volumetric growth: Application to the Guadiana (Spain–Portugal border)

“…Similarly, direct observations of the volume of the littoral drift accumulated against engineering structures (jetties, groins and breakwaters) can provide solid estimates of the longshore transport considering the entire beach system (rather than the upper beach only) if the crossshore transport is negligible or well-quantified (e.g. Bruno et al, 1981;Dean et al, 1982;Bodge and Dean, 1987;Wang and Kraus, 1999;Schoonees et al, 2006;Güner et al, 2011). Some authors have also assessed LST rates based on the infilling of frequently dredged pits at harbours (e.g.…”