[M-IS06] Extreme Weather and Disasters in Southeast Asia

[MIS06-07] Dynamics of Land Cover Changes and Their Vulnerability to Extreme Flood in the Bengawan Solo River Basin of Indonesia

★Invited Papers

*Badri Bhakta Shrestha¹, Mohamed Rasmy¹, Takafumi Shinya¹ (1.International Centre for Water Hazard and Risk Management, Public Works Research Institute, Tsukuba, Japan)

Keywords:Extreme flood event, Land cover change, Southeast Asia, Vulnerability

Because the level of flood risk has been increasing due to deforestation, development, and rapid urbanization activities, land cover changes have become a serious concern in many Asian developing countries. The land use and land cover are changing rapidly and becoming more vulnerable to floods in those countries, increasing the environmental risk. Therefore, it is necessary to understand the dynamic changes in land cover and their vulnerability to flood risk for reducing environmental risk in future. In this study, we focused on analysis of dynamic changes in land cover in the Bengawan Solo River basin of Indonesia and assessed vulnerability of each land cover class to flood risk. The land cover maps for the past years 1990, 2006, and 2020, published by the Ministry of Environment and Forestry, Indonesia, were used to analyze land cover changes in the past, and the land cover maps for the future were projected using QGIS plugin tools to analyze potential changes in land cover in the future. To assess the vulnerability of land cover, flood hazard was analyzed using the Water Energy Budget-Based Rainfall-Runoff-Inundation (WEB-RRI) model. The WEB-RRI model was calibrated and validated by comparing the calculated discharge for past flood events with observed discharge. Flood inundation map for extreme flood events in the past was prepared using the results obtained from the WEB-RRI model. Then, changes in flood-affected areas of each land cover class due to the dynamics of land cover changes were analyzed using the historical and projected future land cover maps and prepared flood inundation map. Finally, the vulnerability of each land cover class to extreme floods was investigated. The findings show that the settlement and built-up areas are increasing and may increase more in the future. While paddy field areas are decreasing due to the conversion of paddy areas mainly into settlement and built-up areas. The results also show that large areas of paddy fields and settlement and built-up areas in the basin are vulnerable to floods. The results of this study can be useful for land use planning and regulations and for formulating policies required for reduction of flood disasters.