Environmental Engineering Reference
In-Depth Information
Rather than digging up roads and widening/adding existing sewers, which would be highly disruptive
to the busy traffic and interfere with numerous existing underground structures and utilities, an upstream
storage scheme is devised. The economic drainage improvement plan calls for the construction of a
100,000 m 3 underground storage underneath the Tai Hang Tung Recreation Ground. Part of the flood flow
will be intercepted by a system of side weirs. The stormwater that overflows into the underground tank
will be temporarily stored; the flow diversion serves to attenuate the flood peaks and prevent downstream
flooding. The success of the scheme depends on the proper functioning of the side weir system and the
hydraulics at the channel/weir junctions. For example, too early a spill into the storage tank may use up
needed storage capacity for a later storm peak.
Fig. 8.15 Schematic diagram of Tai Hang Tung Storage Scheme and triple weir system (Lee et al., 2002)
Lee et al. (2002) conducted experiments to study the complicated turbulent flows in the stormwater
drainage system and optimize the design of the side weir system and the inlet and hydraulic transition. The
experimental results were also used for providing the side weir head-discharge characteristics for a 1-D
numerical unsteady flow model developed to study the flow within the side weir system (Lee et al 2000,
2001a; Henderson 1966; Novak and Cabelka, 1983). The research results provided an understanding of the
highly complex 3D junction flows for the successful design of these schemes. The Tai Hang Tung Storage
Scheme and the Kai Tak Transfer Scheme enhanced the flood control capacity to cope with a 50 year
rainstorm. The schemes are environmentally acceptable and ware built safely with minimal public disruption.
8.3 Estuarine Hydrography and Tidal Flushing
An estuary is a semi-enclosed coastal body of water which has a free connection with the open sea and
within which sea water is measurably diluted with fresh water derived from land drainage (Cameron and
Search WWH ::




Custom Search