PROJECTION OF SHORELINE RESPONSE TO RELATIVE SEA-LEVEL RISE USING THE MODIFIED BRUUN RULE

Abstract

 The beach profiles obtained from the Japanese coasts were examined to evaluate the applicability of the modified Bruun rule proposed by Dean and Houston (2016). Five beaches that experienced land subsidence were selected, and the relative sea-level rise was calculated. The projections carried on these beaches using this rule showed that shoreline response to relative sea-level rise could be calculated with an accuracy of 1.0 m/year. Beach profiles of 10 beaches, including the five mentioned previously, were compared to the profiles estimated using the formula expressing the equilibrium beach profile. The projected changes on these 10 beaches based on the equilibrium beach profile were approximately 0.5–2.8 times grater than the observed maximum shoreline change. The results of the examination on the Southern Kujukuri beach suggested that the accuracy of shoreline projection depends on the accuracy of the estimated amount of longshore drifting sand. Further, some instructions that we should follow when employing the modified Bruun rule were discussed according to these findings.