Applying Mike21-FM to simulate and assess the change of hydraulic paramenters and seabed topography at t groin system suffered from typhoons

Abstract

    Nam Dinh coasts are suffered from natural disasters such as typhoons, storm surges annually, resulting severe damages of sea dike. In order to strengthen sea dikes, one of solutions is to build the groin systems along the coasts at Giao Thuy, Hai Hau and Nghia Hung districts. After the sometimes operation, it shows that foreshore was deposited significantly and hydraulic parameters such as wave, current are reduced at the groin places. Mike21-FM is used to simulate and assess the the impact of typhoon namely Damrey that landed to Nam Dinh Coast from 21 to 27, September, 2005 to hydraulic parameters as well as sea bottom at Dong Binh and Xuan Dai (Hai Hau), where T groin system is supposed to apply. Result shows that wave height is reduced from 3m at the location 3 km far from the coastline to 1.5m at the front side and less than 1m in the back side of the T groin; significantly changing of velocity fields in the narrow areas around the groin system is caused to create large scoured holes in front of T groins, while the erosion in the back side of the groins is slightly reduced. The simulated results help to select appropriate design parameters for stabilization of structural system as well as reduce of erosion during the typhoon period. The strong sea dike system will support to socio-economic development of Nam Dinh province.