Inlet change in Tam Giang - Cau Hai lagoon and coastal flood

Abstract

The Tam Giang – Cau Hai lagoon is related closely to the survival of nearby million inhabitants of Thua Thien - Hue province. It is connected to the sea by two inlets, generally. However, during its natural evolution, the lagoon is also in the situations of one or many inlets, which are sometimes regarded as the coastal risk. Locating in the region with the annual rainfall of 3,000mm (highest in Vietnam), the closing of lagoon inlet has contributed significantly to the strongly coastal floods. During last 50 years, six among seven strongest coastal floods have felt in the periods of the Tu Hien inlet closed. The floods have caused the serious consequences such as the loss of human life, livestock, brackishwater aquaculture, crops, damage of infrastructure, and expanding pollution. The floods have also freshened lagoon water, degraded lagoon ecosystem and decreased biodiversity. The management of inlet change must be regarded as a prior issue of the lagoon management. The remote sensing data play an important role in monitoring and detecting inlet change for the purpose of predicting flood and inundation in the coastal lagoon area.