Dead fish on the banks of Poyang Lake in Jiangxi. (Photo/Xinhua)
An extended drought has led to a sharp reduction in the water levels of China's largest freshwater body, the Poyang Lake, which is located midstream on the Yangtze River, prompting water resource experts in the river basin to propose the construction of a dam to protect the lake, Time Weekly reported.
A controversial Poyang Lake water conservation project, which was believed to seasonally obstruct the exchange of fish between the Poyang Lake and the Yangtze River, came under the spotlight due to the lingering drought in Central and East China's provinces. This drought has had a devastating impact on the environment around the lake.
The problem is that it still needs to be ascertained how serious the drought is. What impact will it have? How did the Poyang lake benefit from the water conservation project, which had an extremely large budget of 12 billion yuan (US$1.9 billion)?
A water resource researcher said it was normal for the Poyang Lake to experience declining water levels between late August and September. However, this year, the situation was particularly serious because the worst drought in the last 50 years has reduced the Yangtze River's water levels to their lowest in five decades.
On Sept. 24, the water level of the Xingzi station at the Poyang Lake, which is connected to the Yangtze River, dropped to 15.46 meters, while water levels at the Huko station on the Yangtze River also slipped to 15.35 meters.
The situation is expected to worsen in October, when the Three Gorges Dam will begin holding back water for electricity generation, which could cause the water level in the Yangtze River to drop further. Moreover, by then, the Poyang Lake will enter the drought season, which will last until late March in 2013.
In the past few years, the drought season has lasted between 113 and 148 days. However, after 2011, the period has grown to 175 days.
The construction of the Three Gorges Dam was proposed because the longer drought period had caused a significant decline in water flows to downstream areas.
On the other hand, over the past few years, reduced rainfall, rampant sand dredging, and the construction of about 29 dams in upstream Yangtze River has caused the size of the Poyang Lake to shrink rapidly, from 4,000 square kilometers at its peak to 200 square kilometers in January, with water levels plunging to a six-decade low of 7.93 meters.
All these factors contributed to the drying up of the lake, severely impacting the agriculture, fishery, navigation and water-supply sectors in the Jiangxi Province, where the lake is located.
To cope with the water shortfall, authorities from Jiangxi introduced several editions of the Poyang Lake water-conservation project and proposed building a dam to help hold water in the lake.
The project was designed to create economic gains from electricity generation, fishery, navigation, irrigation and water supply, but also sparked environmental concerns.
However, local authorities said the dam-building project on the Poyang Lake would have little impact on the environment and the variety of fish species and migratory birds in the area.
The project received preliminary approval from the Ministry of Water Resources, an expert said. The dam, consisting of sluice gates, would only control the water level in the lake and might also provide relief against the severe droughts that had become common in recent years, he added.
The proposed dam would be built across the narrowest part of the channel linking the Poyang and the Yangtze, which is 2.8 kilometers wide.
The lake is a key water source for around a million people and also serves as a natural habitat for numerous migratory birds and aquatic species.