The Bangkok Post ran this story on 22 February:

Ever since the completion of a few dams across the Mekong river in China, the once mighty river, which flows through all the riparian countries except China, has diminished to a trickle every dry season. The situation this year is worse than the previous years and the worst is yet to come with more dams being built.

If they were alive today, our forefathers would be in shock. The mighty Mekong – the traditional lifeline of Chinese, Burmese, Thais, Lao, Cambodians and Vietnamese – has dried up so badly this year that it no longer qualifies to be called a river.

Boat travel from Chiang Rai’s Chiang Khong district to the old Lao capital of Luang Prabang, a popular tourist route has been halted because the water too shallow for boats with the capacity to accommodate more than four people. Cargo boats from China have been stranded in Chiang Saen district of Chiang Rai.

Chirasak Inthayos, coordinator of the Network for the Conservation of Mekong River Natural Resources and Cultures, said that the river’s condition is the worst for more than a decade. He could only imagine how much worse it will be by April, when the dry season normally peaks.

This drying up of the Mekong River is attributable to the closure of four Chinese dams in the upper reaches of the river reportedly to conserve water for electricity generation. The southern Chinese province of Yunnan, which borders Burma and Laos, is reported to be experiencing the worst drought in more than 60 years.

It is obvious that the Chinese government could not care less about the hardships it causes people and countries along the Mekong down river from the dams. Beijing is interested only it its own people and its ever expanding industrial, business and farming sectors. …

I’m sceptical about simplified and sensationalist explanations of environmental change. No doubt, the Chinese dams on the Mekong have all sorts of environmental and social impacts, but is there really good evidence to support the claim that they have significantly reduced dry-season flows downstream?

Can anyone point us to some long term data on dry season stream flow that would illustrate this sudden decline? I’ve had a very quick search but cannot find any long term data. I did find this report from the Mekong River Commission that states:

There is little evidence from the last 45 years [up to 2004] of data of any systematic changes in the hydrological regime of the Mekong. … There has been a lot of debate about the dry season hydrology of the mainstream and there is a widespread belief that there has been significant change due to upstream reservoir storage in China. Figure 4.8 shows the minimum daily discharge averaged over a sequence of 90-days in each year from 1960 to 2004 for Vientiane and Kratie. Such a “long duration” statistic can be regarded as an effective measure of dry season flow conditions from year to year. The data show that:

• There is no evidence of any systematic change in the low-flow hydrology, either in terms of a long-term increase or decrease in dry season discharge.
• The plot includes a range of ±2 standard deviations either side of the longterm average 90-day annual low flow. Years when the flows lie outside of this range may be considered exceptional, the most recent of these being 1999 (or the dry season following the poor flood season of 1998).
• Current claims that the low-flow hydrology of 2004 was exceptional and far below “normal” appear unfounded and are probably linked to the fact that the previous years from 2000 onwards had above average flows during the dry season.

I would be interested in seeing an analysis that extends to 2009, and which focuses on river flow at Chiang Saen and Luang Phrabang, where the relative influence of the Chinese section of the river is much greater.

Interestingly, today the Bangkok Post has a report about water shortages throughout Thailand:

An early drought is raising fears of a “water war” among rice farmers, the Royal Irrigation Department says. Large reservoirs and dams are only about 66% full, director-general Chalit Damrongsak said yesterday. The department fears there will not be enough irrigation water to last through the hot season. The country could not avoid a severe drought if water use exceeded earlier predictions, Mr Chalit said.

Are the Chinese dams to blame for these shortages too?