Flood protection standards are one of the most important elements of flood control and prevention strategy.  Factors such as land use, economic growth, socio-economic needs, consequences of flooding and benefit-cost analysis of flood mitigation measures have been considered in developing the standards.  The Government has formulated a set of flood protection standards for the planning and design of the public stormwater drainage systems in Hong Kong and there are different standards for different elements of the drainage systems.  In summary, DSD adopts the following standards, which are comparable with developed countries overseas.

Types of Drainage Years
Urban drainage trunk systems 200
Urban drainage branch systems 50
Main rural catchment drainage channels 50
Village drainage 10
Intensively used agricultural land 2 - 5

Notes: The definition of flood level is based on the combination of rainfall intensity and sea level. 

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