Abstract—Flood is a natural phenomenon which is difficult to avoid but can control. Flood hazard tends to escalate into disaster, especially in urban areas, due to the high concentration of population. Therefore, flood mitigation measures have become one of the main discussing point in the society. Nowadays there has been a significant move from flood protection to flood risk management. Spatial planning has been identified as one of the fundamental flood management measures, since it can influence the incidence of flooding and its consequential damage, by regulating the locations of activities, types of land use, and scales of development and designs of physical structures. In order to develop such a successful spatial plan, it is important to identify the suitability of the land for the development. However, adequate attention is not still paid to develop a proper mechanism for evaluating this development suitability. The main objective of this research is to analyze the development suitability of the lands, considering both Emergency Evacuation Easiness and the flood risk level of the land. This analysis will be useful to develop a set of guidelines for the future development activities. The research has used the Geographical Information System based approach to model the development suitability of the lands. Two main aspects were assessed in this regard: flood risk level and emergency evacuation easiness. It was assessed by taking the Rathnapura MC as the case study area and the uncertain event as the flood disaster. The research resulted a development suitability map displaying the development suitability levels of each land plots of the study area. This map is very useful for urban planners to decide which type of development is suitable for different areas considering the natural disaster. The same method can be applied to other natural disasters to get an idea about the development suitability of the areas which frequently affect with natural disasters.