Abstract: The construction of hydropower stations in the Lancang River basin since the 21st century will bring about far-reaching influence on the ecological environment in the basin. In this paper the impact of cascade reservoirs on water temperature along the Lancang River was examined via interpolation method, data homogenization and significant difference analysis according to the results of three observations on water temperature and historical hydrological data in the Yunnan segment of the Lancang River. Research results imply that: (1) the water temperature along the Lancang River before and after the construction rises linearly with the decline of latitude and altitude; (2) in a holistic sense of the entire basin, the construction of cascade reservoirs has no significant impact on the water temperature change along the river. The research findings offer reference for the joint dispatching of cascade reservoir groups by providing holistic understanding of water temperature change in the whole basin.

Key words: cascade reservoirs, water temperature of discharge water, variations along the river, latitude, altitude, mainstream of Lancang River