Flood and land cover change analyses were used to assess the dynamics of flood in the floodplains of Tanay River. Flood simulation was carried out using the derived hydrograph under different land cover scenarios to analyze the effects of land cover changes on the flood regime of the river basin in Tanay, Rizal. The model was calibrated using the measuredwater depths and discharge of the river cross-section. Land cover analysis revealed that the watershed is predominantly covered by orchard plants and grasses with an approximate area of about 2286.68 and 1157.4 ha, respectively. Reforestation of the grasslands in the upper portion of the watershed can considerably reduce the volume of floodwater in the floodplains of the river. Flood simulation using the land cover of the area predicted the flood depths and delineated the spatial extent of flooding in the floodplains of the river. The total area that may be saved from flooding if the grasslands in the upper watershed are reforested is about 16.4 ha. About 12.4 ha is located in Barangay Plaza Aldea. The two major environmental adaptive measures that need to be done are the development of a comprehensive community-based rehabilitation and management of Tanay watershed and the protection of the remaining watershed of the area.

The combination of flood modelling and socio-economic analysis was used to determine the flood vulnerability of the towns of Santa Maria and Mabitac, Laguna, Philippines. Geograhic Information System (GIS)-hazard mapping and vulnerability-resilience indicator were used to assess the interaction of a flood hazard and the socio-economic conditions of the people in the area. The Hydrologic Engineering Center Hydrologic Modelling System (HEC-HMS) and Hydrologic Engineering Center’s River Analysis System (HEC-RAS) modelling system was used to derive the synthetic hydrograph and delineated the inundated areas in the flood-prone barangays (village) of Santa Maria and Mabitac. The flood modelling predicted the flood depths in seven out of ten communities and delineated the inundated barangays of the two towns. The social vulnerability analysis indicated that Barangays (village) Jose Rizal, Masinao, Adia and Coralan in Santa Maria and Barangays San Antonio, Libis ng Nayon, Bayanihan, Pag-asa, Nanguma and Lambac in Mabitac are very vulnerable to flooding. The study revealed environment-related aspects that are helpful in reducing the impacts of flooding such as, strengthening the flood warning system and emergency response capacity through flood hazard zonation mapping and rehabilitation of the watershed in Santa Maria.