2017 TYPHOON LAN RECONNAISSANCE FIELD SURVEY IN COASTS OF KANTO REGION, JAPAN

Abstract

Based on our preliminary survey, which began 13 days after the landfall of Typhoon Lan, this paper assesses the situation along the coastline of Kanagawa, Chiba, and Tokyo, with a particular emphasis on the damage to coastal and port structures. It also discusses the research necessary to mitigate the future coastal flooding risk in and around Tokyo Bay. Storm-surge height, wave run-up height, coastal erosion, and infrastructure damage in various places are given. Extensive scouring was observed at a yacht harbor on Enoshima Island and at Kanaya port, where the elevation of the dykes was 7.3 m and 5 m from Tokyo Peil (TP), respectively. Waves overtopped and destroyed a long stretch of the breakwater parapet in Akiya Fishery Port and Kanaya Port. The highest elevation of wave run-up was 6.7 m from TP, recorded at a restaurant on a coastal hill in Tateyama. The maximum storm-surge heights at the tidal stations of Kana-gawa, Tokyo, and Chiba Prefecture was 2.47 m (Banyu river bridge station), 1.28 m (Horie), and 1.21 m (Mera), respectively. Analysis based on best track data shows that Lan was one of the strongest, largest, and fastest typhoons ever to make landfall in Kanto.