Guangdong
Province?is under threat of a "salt tide" that could
severely affect its water supplies, according to the Guangdong
Provincial Department of Water Resources.
The salt tide, which happens every year, occurs when water
reserves dry up in a drought, only to make way for seawater to
flood them.
The chlorine hydronium - the main element in salt - content in
the water in Modaomen Watercourse, a main channel between Zhuhai
and the sea, has exceeded 6,000 milligrams per liter, much higher
than the maximum 250 milligrams per liter limit allowed in drinking
water.
Zhuhai City, which has been grappling with the problem since
September 18, cut off water reclamation for two days, the Zhuhai
Municipal Department of Water Resources said.
From the end of last year to May 2005, Guangdong experienced the
most serious salt tide "attack" in two decades as a result of a
severe drought in South China.
"Guangdong had little rainfall after it suffered serious floods
in June, and Typhoon Damrey did not make much of a difference to
levels of precipitation," Tu Xinjun, a professor on water resources
from Guangzhou's Sun
Yat-sen University, told China Daily yesterday.
"The salt tide will be more serious from January to March next
year, as past experience indicates," Tu added.
The water volume in all of Guangdong's reservoirs only increased
by 140 million cubic meters after Damrey hit, too little to ease
the drought.
According to a provincial department report, the water in the
Xijiang River, which runs through southern Guangdong Province and
the Guangxi
Zhuang Autonomous Region, was reduced by 52.9 percent from last
year because of drought and the lack of rainfall.
Tu said salt tides can't be prevented but the damage caused can
be mitigated.?
He gave the example of a creative water dispatch project carried
out in May in which the Ministry of Water Resources ordered the
provinces in the upper reaches of the Xijiang River to discharge
851 million cubic meters of water to Guangdong.
The Guangxi Zhuang Autonomous Region and Guizhou
Province participated in the dispatch project. The discharged
water flowed over more than 1,000 kilometers in 18 days to the salt
tide-affected areas.
(China Daily September 29, 2005)