Will China's dams control the Mekong's flow?

Recent reporting linked to China's Jinghong dam in the far south of Yunnan province raises questions about the extent to which China's dam-building program on the Mekong River will affect mainland Southeast Asian countries downstream.

Jinghong Dam on the Mekong River in China

The Jinghong dam is the most southerly of the 'cascade' of dams China has built, or is building, on the upper reaches of the Mekong River to generate hydroelectricity. Although I observed preliminary work taking place at the dam site upstream from the town of Jinghong as long ago as 2004, official authorisation for construction of the dam was not given until 2008. Since then, rapid construction has  led to the dam's completion; it has been in operation for at least two years now.

Given its geographic proximity to its downstream neighbours Laos and Thailand, and more distantly to Cambodia and Vietnam, there has been ongoing concern in those countries about the extent to which the dam's operations — either the release or the holding back of water from the dam — could affect the use of the river for navigation and fishing. Indeed, concerns about these matters have been raised from the moment construction began, with repeated reports of rapidly fluctuating water levels affecting fishing catches particularly in the region around Chiang Saen in northern Thailand.

During the wet season in September of last year, concern was expressed by many observers in Thailand that increased water flow down the Mekong could result from Chinese authorities discharging large amounts of water from the Jinghong dam at a time when monsoon rainfall meant that the river's level was already very high.

But on this occasion the Mekong River Commission, which monitors water levels, reported that, contrary to fears about possible Chinese actions, there was was no reason to judge that water released from Jinghong would cause flooding downstream.

Now the question of Chinese control over water releases from the Jinghong dam has moved to the opposite concern.

There have been several reports that the Mekong River is currently at such a low level that cargo boats traveling between Chiang Saen and Guan Lei, the large river port in the far south of Yunnan province, have run aground. The Mekong's water level is always low in February, with the of snow melt from the Himalayas into the river diminishing and the southwestern monsoon yet to raise the river's water height. At this time of year, the river's water level falls below the 1 to 1.2 metres of depth required by the shallow-drafted boats using the river, and reports of boats becoming stranded have been fairly common in recent years. What is interesting about the current situation is the reported readiness of Chinese authorities to give an account of their actions in releasing water from the Jinghong dam on the Mekong to rectify the situation.

The attention now being focused on the Jinghong dam raises broader questions about the long-term consequences of China's dam-building program. If action, or inaction, at Jinghong can have the effects ascribed to it, what will be the effect of water control at China's other dams? Will China's operation of the dams be for the greater benefit of all Mekong countries or simply for its own interests linked to the generation of hydroelectricity? And what will be the ultimate effect of the fact that China's dams on the Mekong are holding back sediment from flowing down the river? This is an issue being studied by a University of Hull research team, as reported on a recent BBC program 'Science in Action'.

Concerns about China's operation of its Mekong dams are directly linked to the future well-being of the more than 60 million people who live downstream in the Lower Mekong Basin. The populations of Laos, Cambodia and Vietnam are deeply dependent on the river functioning as it has for centuries: as a rich source of food and a key to productive agriculture.s control the Mekong's flow?