Originating from the Qinghai-Tibet Plateau, flows through the Hengduan Longitudinal Valley and Yunnan-Guizhou Plateau. The elevation of the Tibetan Plateau during the Tertiary period was an important factor in the genesis of the south-west monsoon, which is the dominant climatic control influencing the hydrology of the Lancang Basin. The physical and geographical conditions of the river basin are basically similar to the Nu River Basin, and the spatial and temporal distribution of floods have many common characteristics and basic laws within China (Figure 1).
Figure 1. Map of the river system in the Langcang River basin, Southwest China
The Langcang is already heavily dammed, with many more dams planned and under construction. China has already built ten or eleven cascade dams on the Langcang mainstream since 1995. As of November 2016, China has five more under construction, and another 11 planned or proposed. Laos has two dams under construction on the mainstream, and another seven planned or proposed; Cambodia has two planned or proposed. The Mekong is the fastest growing large river basin in the world in terms of hydropower construction. The scheme is expected to change the river’s natural flood-drought cycle and block the transport of sediments, affecting ecosystems and the livelihoods (Figure 2).
Figure 2. Longitudinal Profile of Lancang River Cascade Development