Hanoi, the capital of Vietnam, is adjacent to the Hong River and has many streams and lakes. Recently, the low flat terrain around Hanoi is going to be urbanized, so flood control has been a quite important issue. In this study, current status of water flow in the Hong River and its branches was investigated based on field observation, interview survey, and collection of materials in order to examine the effective flood control. Firstly it was pointed out that many branches do not have enough capacity as a flood way due to the meandering river course, tree growth, and riverbed rise. Moreover around the river is already urbanized. Therefore those rivers should be utilized for drainage of rain water in a city and irrigation water mainly, and flood control measure should be taken in the main stream of the Hong River. But in the Hong River, it was clarified that the embankment is being eroded due to its fragile geological condition. So the water level has to be much lower than the height of embankment and capacity is not enough. In such a river, the dangerous area was predicted based on the comparison among the water leakage point, location of old river course, and current stream line. In this study, I suggested improving and taking advantage of current alignment of the embankment that is determined by the natural dynamism of rivers and pointed out the necessity of wide scale flood control.
Hanoi, Hong River, Branches, Bank Erosion, Alignment of embankment