Coastal processes and longshore sediment transport along Kundapura coast, central west coast of India

Abstract

Longshore sediment transport (LST) is one of the main factors influencing coastal geomorphology. This study examines the variation in the LST estimate using four well known formulae and the sensitivity of wave parameters on LST determination. The study was done along the Kundapura coast, central west coast of India. The Delft3D-wave module was used for obtaining the nearshore wave characteristics from the wave data measured using Datawell directional wave rider buoy at 12m water depth for a period of one year. Diurnal change and seasonal variation in LST were examined. The study shows that the net LST was toward north for most of the time (non-monsoon period) during the year when predominant wave direction was between SWS and SW, whereas the LST was toward south during the monsoon season when the wave direction was from the west. It was found that the influence of breaker height was more during the non-monsoon period whereas during the monsoon period, breaker angle shows more influence on LST. Estimated annual net LSTR for the region is 3.6, 3.0, 1.6, and 2.6×105m3 based on the CERC, Walton and Bruno, Kamphuis and Komar formulae. The LSTR estimate based on the Kamphuis formula, which also includes the wave period, beach slope, and sediment grain size, was found to be a reliable estimate for the study region. The variation in LSTR estimate considering different data intervals was also examined and found that the difference in monthly LSTR for data intervals of 6, 12 and 24h with respect to the 3h interval was up to 11, 13 and 24%. For better and more accurate estimates of LSTR, the data interval should be 3h or less.