Taiwan is frequently hit by typhoon and suffers coastal hazards such as coastal flooding, sea dyke breaking, ocean pollution, coastal erosion etc. These disasters cause enormous damage and result into severe consequences due to the over-exploitation of coastal area. The government is responsible to minimize the loss occurring due to maritime hazards in the coastal area. One of the problems for coastal hazard mitigation is that there is insufficient information for decision making. A decision support system (DSS) for government to prepare and respond to coastal hazards is urgently needed. The DSS contains several components such as the real-time in-situ observation net, the numerical forecasting models and the decision model. These components are probable exist nowadays. However, how to integrate these components to build the decision support system is considerable and necessary. The purpose of this paper is to study the integration of in-situ data and numerical models to establish a coastal hazard decision support system for disaster mitigation applications.