Heavy precipitation events and fluvial flood can cause serious damage to property and fatality, and thus flood disaster management is essential to lower the risk, to prevent and to mitigate the crisis. Effective and efficient flood disaster management requires on-site information, forecast and appropriate corresponding response strategies and measures. Therefore, a concept of integrated decision support system (DSS) for flood disaster management is proposed and discussed in this paper. The DSS integrates observation, rainfall forecast, fast flood simulation, historical events and crisis scenarios, and response strategies and measures, by means of information and communication technology (ICT) and internet of things (IoT). The DSS can provide relevant information and offer suggestions of action before and during the crisis. The DSS can also be utilised for disaster drill, education, and demonstration with the help of virtual reality (VR), augmented reality (AR) or Metaverse technology. The aims of this DSS are to improve existing response strategies and emergency services, to enhance the community-based disaster risk management, and to raise public crisis awareness.