The most serious salt tide that struck the Pearl River estuary
in south China last winter is gradually receding as a result of
increased rainfall in late February.
The Guangdong Provincial Astronomers Society monitoring the
Xiaoying Watergate near the Hengmen Waterway in the estuary gave
the all-clear from February 28 to March 5, the longest salt
tide-free period since last autumn. The waterway empties into the
South China Sea.?
Salinity levels last Friday were 290 grams per liter at the
Dayongkou Watergate near the Modaomen Waterway, in the same
estuary, also a record low since last autumn. The chlorine content
at the same site was above 5,080 milligrams per liter between
February 17 and 28.
The Pearl River estuary fell victim to repeated salt tides as a
result of reduced rainfall in autumn and winter, especially in and
around
Guangdong Province, the worst in recent years.
The salt tide gravely affected drinking water supplies in the
densely populated Pearl River Delta, where major cities such as
Zhuhai, Zhongshan, Panyu, Dongguan and Shunde are located.
However, heavy rainfall in the drainage area of the Pearl River
on February 18 and February 27 increased water levels and reduced
salinity content in the Xijiang, Beijiang and Dongjiang, all
tributaries of the Pearl River.
Salinity concentrations are expected to continue to drop
throughout March.
(Xinhua News Agency March 6, 2006)