摘要: One of the great rivers Asia, Mekong ranks twelfth in list longest world. It rises Himalayas at c. 5000 m AMSL, close to Dzanag La Pass Tanghla Shan Mountains, on NE rim Tibetan Plateau (Fig. 1). Along its 4200 km course, it flows through or along borders six countries: China, Burma, Lao PDR Thailand, Kampuchea and Viet Nam, before emptying into South China Sea. In terms mean annual discharge (c. 475 x 109 m3 a−1) sixth The total drainage basin 783 000 km2 includes 160 12 611 Kampuchea, Thailand Nam together (the Lower Basin). Very little information is available for upper 1800 km, Tibet, Burma. However, lower 2380 from entry Basin Burma—Lao PDR—Thailand boundary Sea, has been well-studied UN-sponsored water related resources development programme, Project, launched some 25 years ago. This chapter concentrates River basin, shown Fig. 2.