Trong những thập kỷ gần đây, ngày càng tăng phát thải khí nhà kính đã gây ra sự nóng lên toàn cầu dẫn đến nhiều thay đổi bất lợi của môi trường đặc biệt là mực nước biển gia tăng và chế độ thủy văn. Lưu vực sông Đồng Nai có một phần hạ lưu dưới mực nước biển là một trong số các lưu vực dễ bị tổn thương nhất với biến đổi khí hậu. | VNU Journal of Science Earth Sciences 27 2011 25-31 Assessment of climate change impacts on flooding in the downstream of the Dong Nai River Tran Hong Thai Vietnam Institute of Meteorology Hydrology and Environment 23 62 Nguyen Chi Thanh Hanoi Vietnam Received 10 January 2011 received in revised form 22 January 2011 Abstract. In recent decades the increasing in greenhouse gas emission has caused global warming leading to many adverse changes of the environment especially the sea level rise and the hydrological regime. The Dong Nai river basin having the downstream part below the sea level is among the most vulnerable basins to climate change. Recents studies showed that the sea level in the downstream of Sai Gon - Dong Nai river basin is rising. Many cities downstream of the basin especially Ho Chi Minh city are being flooded in flow tides which seriously affect the socioeconomic development. Thus research on the future impacts of climate change on flooding in this area is of vital importance. This paper applied the HydroGIS modeling package to predict the flooding levels in the Dong Nai river basin for the period from 2020 - 2100 taking into account the impact of climate change. Inundation maps were developed based on three climate change scenarios namely B1 B2 and A1FI and different sea level rise values . 15 25 50 75 and 100cm . These maps together with comprehensive analysis on the trend and extent of flooding will assist decision makers in developing mitigation measures coping with flooding in the river basin. Keywords Climate change flooding Dong Nai river HydroGIS. 1. Introduction Climate change has become a globally significant concern in the 21st century because of its potential impacts on society. Vietnam is not an exception. According to recent studies by World Bank and IPCC Vietnam is among the countries most heavily affected by the consequences of climate change. Mekong and Red rivers delta are projected to be the most seriously inundated. With sea