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Long shore sediment transport computation for Hai Hau beach - Nam Dinh province

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In this study, it is shown that the prevailing wave climate in connection with the complex topography of Balat river mouth and Hai Hau beach promotes erosion along the coastal line. A two dimensional random wave transformation model was used with 20-year time series of hindcast waves to compute the long shore sediment transport along the study beach. | Vietnam Journal of Mechanics, NCST of Vietnam Vol. 25 , 2003, No 1 (39 - 48) LONG SHORE SEDIMENT TRANSPORT COMPUTATION FOR HAI HAU BEACH-NAM DINH PROVINCE NGUYEN MANH HUNG Institute of Mechanics, NCST of Vietnam ABSTRACT. Several stretches of shore line in the Red River Delta (RRD) are suffering from severe erosion, especially an area between too large river mouths Balat in the North and Day in the South, known as Hai Hau beach. Several different hypothesis have been put forward to explain this erosion. The cut off of the Ha Lan river mouth (in 1955) which discharged sediment at the upstream end of the beach, possibly affects Hai Hau beach. Also, the construction of Hoa Binh dam in the upstream part of Red river has reduced the sediment supply to the area. In this study, it is shown that the prevailing wave climate in connection with the complex topography of Balat river mouth and Hai Hau beach promotes erosion along the coastal line. A two dimensional random wave transformation model was used with 20-year time series of hindcast waves to compute the long shore sediment transport along the study beach. 1. Introduction Hai Hau district consists of about 34km of coastline and 48km of river embankment. Despite protection measures, intensive long-term erosion occurs there, posing very serious problems in both economy and social development of Nam Dinh province in particular and of provinces belonged to Red River Delta in general. According to different reports the average rate of erosion ranges from 5 - !Om/ year to 30m/ year. Over the last 90 years, about 15-20km long and 2.5km wide strip of Hai Hau beach was lost to the sea [9] . In spite of the important of the Hai Hau beach and the other coastal areas of RRD relatively few comprehensive studies have been carried out to calculate the sediment transport and shore line erosion of the studied area. The most difficulty in carrying out such studies is the limited of data on hydrodynamics and sediment transport. So, in