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Deep Bay drowning in the sea?
Over the past months, WWF Hong Kong has become increasingly
concerned about reports in the local newspapers outlining the proposal
by the Shenzhen SEZ Government to use water from Mirs Bay to flush into
the Shenzhen River in order to dilute the pollutants in the River. The
latest newspaper report was in the Hong Kong Commercial Daily, 15 August
2003.
http://www.cnwnc.com/gbtobig.php3?url=http://www.cnwnc.com/20030815/ca485963.htm.
The Shenzhen River is severely polluted
by domestic and livestock waste, and is one of the major source
of water pollution into Deep Bay. In June 1995, a multi-million
dollar joint project between the Hong Kong and Shenzhen governments
began to widen and deepen the river in three phases, in order
to increase flushing of the river to reduce pollution and to
alleviate flooding of the surrounding farmland and villages.
Despite having spent HK$1,700 million
on this Shenzhen River Regulation Project, the Shenzhen government
still thinks the River is too polluted and that the next course
of action is to spend a further RMB 950 million to build a pumping
station at Sha Tau Kok and a 13 km long pipe to bring water from
Mirs Bay to flush the Shenzhen River. The annual operation cost
of this proposed project will be some RMB 30 million.
WWF Hong Kong is very concerned about
this proposal since the water in Mirs Bay and Deep Bay has very
different characteristics, with that in the former being marine
and that in the latter being estuarine.
For example, data collected by the Environment
Protection Department in 2001 shows that the salinity of the
water in Mirs Bay ranges from 27.2 - 31.9 ppt as compared with
that in Deep Bay of 0.3 - 23.7 ppt.. Similarly, the turbidity
of the water in Mirs Bay has a range from 6.5 - 11.3 NTU whilst
that in Deep Bay has a range from 25.4 - 209.6 NTU.
The Mai Po Inner Deep Bay Ramsar Site
is of vital importance for some 100,000 migratory waterbirds
that uses the site over the course of the year. In particular,
these waterbirds depend on the mudflat fauna (e.g. mudskippers,
crabs, polychaete) for their food. These mudflat fauna are adapted
to the brackish water conditions of the Bay, such as the condition
of the mudflat soil and the quality of the water in the Bay,
especially the salinity. If the Bay were to be flushed with marine
water of higher salinity, then it is very likely that these mudflat
fauna will die, thus having a knock-on effect on the waterbirds
that uses the Bay.
The present character of the Deep Bay
mudflat has been created over centuries by the pattern of water
flow around the Bay, and the level of silt in the water which
deposits on the mudflat. The proposed project will involve flushing
large quantities of water of low silt content from Mirs Bay into
the Shenzhen River and then into Deep Bay. This will undoubtedly
have a serious impact on the normal pattern of water flow in
the Bay and thus, the mudflat in the Bay. For example, we may
find that in some areas, the mudflat may gradually disappear
because of the extra water flushing it away.
These are just some of the possible adverse
impacts that would occur if water from Mir Bay were to be flushed
into Deep Bay.
If the Shenzhen and Hong Kong governments
are concerned about the problems with pollution entering in the
Shenzhen River, then the problem should be tackled at source,
by controlling the discharge of domestic and agricultural waste.
In fact in April 2003, the World Bank has informed the Shenzhen
Government that they will provide multi-million (US$) dollar
loans to improve the water quality in the rivers that run through
the city, including the Shenzhen River. Flushing the Shenzhen
River out only pushes the problem further out into the Pearl
River Estuary but has not solved the real problem.
WWF Hong Kong is now in contact with the
Hong Kong government to try and find out more details about the
proposed project from the Shenzhen government. We will keep you
up to date on the matter.
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