200 - Typhoon Committee

ESCAP/WMO
Typhoon Committee Annual Review 2007
In Hong Kong
1. Progress in Member’s Regional Cooperation
and Selected Strategic Plan Goals
and Objectives
SWIRLS (Short-range Warning of Intense Rainstorms
in Localized Systems), HKO provided the Drainage
Services Department (DSD) with 1-hour rainfall forecast
in graphical form starting 2006 to facilitate their flood
control operations.
Nil.
2. Progress in Member’s Important,
High-Priority Goals and Objectives
a. Hardware and Software Progress
Hong Kong is often affected by flooding induced by
rainstorms associated with tropical cyclones and other
severe weather systems.
Since 1997, about HK$8 billion worth of major rivertraining
works and flood-control projects have been
completed in the New Territories (NT) over the northern
part of Hong Kong. As a result, the flooding situation in
NT had improved significantly.
To alleviate flooding in low-lying villages, the Hong Kong
Special Administrative Region (HKSAR) Government had
already completed 27 village flood pumping stations
to protect 35 villages where river-training works could
not be effectively undertaken due to low ground
topography.
For the rural areas, the construction of 26 km of drainage
channels and 23 km of stormwater drains were in
progress. Major flood prevention works under planning
and design include 16 km of drainage channels and 1 km
of stormwater drains.
For the urban area in West Kowloon, 45 km of stormwater
drains had been completed. Plan is also in hand to
construct another 4-km drainage tunnel.
For other urban areas, the construction of 22 km of
stormwater drains was underway. Further major flood
prevention works under planning and design include 9
km of stormwater drains and 16 km of drainage tunnels.
b. Implications to Operational Progress
Based on outputs generated by the nowcasting system
Data from raingauges operated by the DSD and
Geotechnical Engineering Office of the HKSAR Government
are relayed to HKO to support the operation of the
Rainstorm Warning System, the Special Announcement
on Flooding in the northern New Territories and the
Landslip Warning System. Saving in operational cost was
achieved by using the government-wide data network
instead of commercial leased lines. The General Packet
Radio Services (GPRS) mobile network and solar panels
were used for data acquisition in some out-stations
where land-based telemetry and electricity supply were
unreliable. Over 65 automated gauging stations have
been installed at major river channels in the territory to
provide round-the-clock real-time monitoring of water
depth, flow velocity and video surveillance.
The rainfall threshold criteria for the issuance of the
Special Announcement on Flooding in the northern New
Territories were revised in March 2006 and continued in
use in 2007, taking into account the improvement work
of the drainage systems in flood prone areas. The time
taken for flood water to recede would also be considered
in canceling the Special Announcement. Operation of the
announcement under the new criteria was satisfactory.
Over 2,400 km of drains, engineered channels, culverts
and watercourses were inspected and maintained in 2006
(updates to be available at end of 2007). At locations
where flooding might cause high risks to the local
residents, local flood warning systems were installed to
monitor the flooding situations and to alert them about
the arrival of floodwater. To effectively and precisely
alert the residents and shop-keepers in a local lowlying
urban district in the heart of Hong Kong Island
for possible flooding due to coincidence of high tide
and heavy rainstorm, an automated flooding information
dissemination system has been implemented since
the 2006 wet season. When the forecast or recorded
hydrological data reach the triggering criteria, advisory
flood alerts would be sent to registered users via mobile
phone SMS messages or pre-recorded voice phone
calls. A list of flooding blackspots was also compiled
to facilitate the deployment of resources to carry out
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