AbstractCascade reservoirs were designed for Yalong River Basin, which ranks the 3rd largest hydropower base in China. Reservoir impoundment has certain impacts on local climate, but few researches focus on this field. This paper integrates the spatiotemporal analysis techniques and geostatistical methods to identify the reservoir projected meteorological indices (MIs) variations as well as the impact scope under different circumstances. Results show: The reservoir projected variations of moisture indexes were much more significant than temperatures. Anthropogenic disturbance has led to dramatic decrease of relative humidity in the past decade, far beyond its periodic amplitude range. Moreover, dry valley faced more serious drought risk but reservoir impoundment of this region alleviated the local drought risk. The daily minimum temperature, relative to the maximum temperature, was more sensitive to catchment changes with an earlier appearance of temperature zone variation. Since impounding, the MIs internal relationships in non-dry valley varied significantly more than that in dry valley, with the positive correlation of 0.7 between the relative humidity and precipitation weakened greatly. The severe warming hotspots distributed in the upper reach and had the probability of 0.95- 1 to exceed 1.5℃ IPCC control target. This study provides references for the disturbance of reservoir impoundment to local climate at multiple temporal-spatial scales under different circumstances and contributes to the MIs variation pattern identification and quantitative risk assessment.
