MULTIPLE REGRESSION ANALYSIS OF EFFECTS OF BAR AND TIDE ON SHORELINE CHANGE

Abstract

The effects of bars and tides on shoreline change were investigated by a multiple regression analysis. The shoreline change rates used for the analysis were estimated from the beach profiles measured every workday during a 22-year period from 1986 to 2007 on the Hasaki coast in Japan. The examined parameters which had the potential to affect shoreline change rates were offshore wave energy fluxes, previous shoreline positions, maximum, minimum and average tides, and inner and outer bar crest elevations. In the multiple regression analysis, parameters which affected the shoreline change rate were selected by comparing the multiple regression models developed by combining the parameters on the basis of the Akaike Information Criterion (AIC) value, and the effects were also estimated by using the coefficients of the best model which had the smallest AIC. The shoreline change was affected by not only the offshore wave energy fluxes and the previous shoreline positions but also the maximum and minimum tides and the inner and outer bar crest elevations. The largest effect was the offshore wave energy fluxes, followed in order by the maximum tides, the previous shoreline positions, the minimum tides, the outer bar crest elevations and the inner bar crest elevations.