Transformations of natural river systems following tremendous cascade development greatly influenced the natural habitats and landscapes in Yun'nan province.Taking hydropower development of Yun'nan Province as an example

this paper analyzed the impacts of the hydropower develop-ment by relating hydropower development status and drought frequencies in the province.The results show that the construction of hydropower has caused a variety of environmental problems such as vegetation destruction and natural landscape fragmentation

biological habitat deterio-ration and species reconstruction

unbalanced hydro-environmental system

and so on.In order to cut down negative impacts on the environment

following protection measures were proposed

i.e.

(1)rational planning for watershed development;(2)standardizing construction procedures and carrying out environmental impact assessment with hydropower development planning;(3)establishing dispatching centers for cascade exploita-tion of the rivers;(4)enhancing environmental propaganda and related scientific research.