Abstract: The impact of reservoir on local climate is an important aspect of environment impact assessment for a hydropower construction project, such as the Zangmu Reservoir, the first large hydropower station on the middle Yarlung Zangbo River. This paper focuses on this reservoir and its surrounding area, and conducts regional land-atmosphere coupling simulations using the Weather Research and Forecasting (WRF) model to examine its influence on regional climate factors－the water and heat exchange between the land surface and atmosphere and the weather process. For the reservoir, different numerical simulation schemes are designed for the WRF model, considering hydrological changes caused by its impoundment, and its impact on the regional microclimate is analyzed based on the simulations. The results show that in this area, precipitation has experienced little change in spring, autumn or winter, while in summer it has manifested an increasing trend since the impoundment. Air specific humidity above the reservoir is increased throughout the year, with the largest increase in spring. Meanwhile, the impoundment has caused an increase in specific humidity across the northeast downwind zone and in the upstream valley. In the impounding area, air temperature 2 meters above the ground has risen, with the smallest rise of 0.4 ℃ in summer and the largest rise of 2 - 3 ℃ in winter. In the surrounding area, temperature has risen in autumn and winter and lowered a bit in summer. The results help environment impact assessment of plateau reservoir construction.

Key words: local climate, Zangmu Reservoir, weather research and forecasting model, land atmosphere coupling, climate change