Three Gorges Dam: drought maker or breaker?

A 200-day drought in central China ignites debate among experts about impact of the dam on local weather systems.

Three Gorges dam - drought maker or drought breaker
Three Gorges Dam was hailed as being able to guarantee irrigation for downstream farmers [EPA]

Completed in 2005, the Three Gorges Dam of central China was hailed as being able to regulate the water levels of the Yangtze River, ease cross-country navigation, and guarantee irrigation for downstream farmers, while also helping to minimise disastrous flooding that the Yangtze was known for.
But a 200-day drought in central China has provoked a major debate among scientists and researchers about the impact of the dam on local weather systems.

Experts say that the 600km reservoir required to serve the 26 turbines of the dam could be partly to blame, preventing considerable amounts of water from flowing downstream.
Other environmentalists and climate specialists have said that the giant reservoir acts like a massive heat reflector, affecting the microclimate of the region. 

They claim that it is raising the local temperatures and reducing the potential rainfall. Scientists also point out that the sacrifice of forests and farmlands that are now under water also result in the loss of helpful carbon dioxide absorbers.
Government officials have a different answer for the drought. Government meteorologists are saying that the seasonal high pressure from the northwest Pacific was weaker and more easterly than normal, thus making it difficult for cold fronts to reach the downstream areas of the Yangtze.
Zheng Shouren of the China Academy of Engineering told the official Xinhua news agency that the drought would have been much worse if not for the Three Gorges dam releasing billions of cubic metres of water downstream. 

But this also comes at a cost. Reduced water levels in the reservoir mean energy production may be cut.
From a meteorological standpoint, six years is a relatively short time to decide which side of the argument is right. More time and more study will be needed to determine if the Three Gorges Dam is a drought maker or a drought breaker.

Source: Al Jazeera, News Agencies