Assessment of Flood Hazard in Hanoi City
This paper presents the results of studying flood hazard and vulnerability caused by flood and flood hazard in Hanoi City. By analyzing satellite images, using GIS and geomorphological features, the authors had assessed the actual state of historical flood happening at the end of 2008. The results show that most of Hanoi’s flat areas are 0-4m submersible in water. Effective level of inundation increases gradually from two sides into the centre and from the north to the south, consistent with obliquity and terrain characteristics of Hanoi City. Some areas in the west, southwest and south of the city (in districts: Chương Mỹ, Mỹ Đức, Ứng Hòa, Thường Tín, Phú Xuyên) are severely affected by flood with deeply inundated areas; inundation level is at danger level of about 2-4m. The districts in the south of Hanoi have the most vulnerable areas, such as the low lands: Mỹ Đức, Ứng Hòa, Thường Tín, Chương Mỹ, Thanh Oai districts. Chương Mỹ District has 117ha at very high-risk level; Ứng Hòa District has 87 ha. In the inner city, Hà Đông, Hai Bà Trưng and Tây Hồ districts have the highest hazard level. The suburban districts in the south of Hanoi haven the largest agricultural and rural residential land, which are often in deep and prolonged inundation, so the flood risk here is also at high level.