Lower Mekong and Tonle Sap in flood, 2001. Source: NASA Earth Observatory
The previous post commented on the conflict between India and Pakistan over the waters of the Indus River. Part of that river arises in the Tibetan highlands controlled by China. China is unlikely to claim much of the flow of the Indus, for in Tibet the headwaters flow through a high altitude region unsuitable for most agriculture and difficult for human settlement, a zone far from the population centers of China. The Mekong which also arises in the southern Chinese highlands is quite a different kind of river, and part of its course is tangential to some of the most fertile and water demanding parts of southern China. In its headwaters area the Mekong is also of some importance for Myanmar (Burma). Along its lower stretches the Mekong is critical for the agriculture and food supply of Cambodia, Laos, Thailand and Viet Nam.
Like many rivers, the Mekong has large seasonal flow variations. The area it passes though is humid but with a monsoonal climate characterized by a distinct dry season in the Northern Hemisphere winter and a wet season in summer. The monsoon rains greatly augment the flow and lead to the annual flooding of Tonle Sap, a very large seasonal lake in Cambodia shown as the dark patch surrounded by green in the late summer view from space above (courtesy of the NASA Earth Observatory). If it were solely dependent on rainfall in its lower stretches, the Mekong would diminish to a trickle in April and May. Water from snow and glacial melt in the highlands helps to regulate the flow and to keep the river continually navigable for small craft over much of its length as well as to allow for irrigation during the dry season in the tropical lowlands. The annual flooding of Tonle Sap is a major source of food for Cambodia, one of Asia's poorest countries as it allows large fish harvests.
Over the past several years the governments of the lower Mekong countries have observed diminished flow and contend that China is diverting waters for consumptive use. They are observing the construction of large dams in China, including one that will be the highest in the world when it is complete, that will allow China to generate hydroelectric power but also to regulate the flow of the river and possibly to construct works for diversion of the river waters for Chinese urban, industrial, and especially agricultural uses. China did not sign The Agreement on the Cooperation for the Sustainable Development of the Mekong River Basin, an agreement between the four downstream Southeast Asian nations to cooperate in the development of the river. Combined with the projected impacts of climate change and periodic drought Chinese actions could lead to serious problems in the lower Mekong and to direct conflict between China and its smaller neighbors. China denies the claims by the downstream countries, but long-term diminution of the flow may make that denial difficult to accept.
The potentials for conflict over the Mekong are quite different from conflict over the Indus, especially as six countries are involved, but as publications over the past winter (dry season) have illustrated, the possibility is real and potentially dangerous.
