Author(s): M. Habibi
Keywords: Longshore Sediment Transport; Sediment Trap; Sediment MeasurementCaspian Sea; Babolsar Beach; Iran
Abstract: In this paper, using 6 known methods of estimation of alongshore sediment transport including Bijker (1971), C. E. R. C (1984), Kamphuis (1986), Kamphuis (1991), Kraus (1982) and Van der Meer (1990) the alongshore sediment transport rate (ASTR) is predicted for Babolsar shore, located in the south coast of Caspian Sea. The results have shown large amount of discrepancies among the predicted values. In order to investigate the accuracy and validity of empirical methods for estimating ASRT in the south coast of Caspian Sea, a field measurement was conducted to measure the impoundment of sediment behind Babolsar breakwater, which was deposited due to wave action on the beach. Based on this measurement the annual alongshore sediment transport rate for Babolsar Coast was obtained 284193 tons. The results showed that Kamphuis (1986), Bijker, CERC formula with coefficient of 0.77 (recommended by Shore Protection Manual), and Kraus overestimated the transport rates and Kamphuis (1991) and Van der Meer formulae have under-estimated ASTR. However, the method of Van der Meer is more appropriate for Babolsar condition and can be recommended for application to the south coast of Caspian Sea. Also a filed measurement was conducted to measure ASTR using sediment traps in Babolsar coast. The measured values were compared with those calculated from the six selected empirical formulae. The results showed that for this specific state of the sea, the measured transport rates were considerably lower than those predicted by empirical formulae. It was shown that the predicted ASTR by Kamphuis (1991) formula was about 5 times lower than the one predicted by CERC formula and was closer to the measured values.