Nearshore wave-power dissipation and the coastal energy regime of the Sydney-Jervis Bay region, New South Wales: a comparison

Abstract

Analyses were performed on wave data obtained over a period of 2 years from the Botany Bay offshore wave rider to estimate the role of shallow water modification and frictional dissipation on the coastal wave regime of the region from Sydney to Jervis Bay, N.S.W. Owing to the steep nearshore profile which characterizes this region, the seaward limit of wave-induced sediment motion is less than 1 km offshore for 50% of the time and exceeds 3.5 km only 1 % of the time. Correspondingly, the narrowness of the active nearshore zone minimizes the amount of wave power expended by nearshore bed friction: on the average only 3.4% of the incident wave power is dissipated before reaching the inshore zone. By contrast, friction-induced power expenditures over the low-gradient nearshore profiles fronting the coasts of Sergipe (Brazil), Santa Rosa Island (Florida, U.S.A.), Cape Henry to Cape Hatteras (U.S.A.), and Georgia (U.S.A.) average 29, 48, 58 and 84% respectively.