Assessment of Climate Effects in the Three Gorges Reservoir Based on Multi-source Fusion Data CLDAS

In order to alleviate the problem of water scarcity, adapt to and mitigate the negative impact of climate change on water resources, large-scale infrastructure projects have been built worldwide. In addition to bringing huge social benefits, reservoirs may also affect meteorological conditions near the surface and mesoscale or weather scale processes. A high-quality meteorological dataset is an important foundation for understanding climate change. Considering the complexity of the underlying surface in the Three Gorges Reservoir region, this study uses CLDAS multi-source fusion grid meteorological data to study the characteristics of changes in the Three Gorges Reservoir before and after water storage. Select four elements: temperature, precipitation, wind speed, and relative humidity, and analyze the climate effects before and after the Three Gorges Reservoir from different time scales such as year, season, and day. Based on the analysis of CLDAS multi-source fusion data, it is shown that for the average temperature, after the water storage, except for the areas along the southern side of the Yangtze River where the temperature is lower than before the water storage, most other areas are higher. On an annual scale, there is not much difference in average temperature before and after water storage. The average temperature effect in the Three Gorges region after water storage varies at different time periods. During the subsidence period and high water level period, it shows an overall warming effect, with an average temperature increase of 0.1 ℃ and 0.3 ℃, respectively. However, during the flood season and water storage period, it shows a cooling effect, with an average temperature decrease of 0.2 ℃ and 0.9 ℃, respectively. The cooling effect is more pronounced during the water storage period. After water storage, it shows an increase in temperature during the day and a decrease in temperature at night. For annual precipitation, except for some areas in the east, northwest, and central regions where precipitation has decreased, most of the remaining areas of the Three Gorges generally have more precipitation than before the water storage. At the annual scale and different time periods, the precipitation in the Three Gorges area is higher after the water storage than before, and on the annual scale, the precipitation after the water storage increases by 8.8% compared to before the water storage; During the subsidence period, flood season, storage period, and high water level period, the precipitation after storage increased by 10.2%, 1.3%, 21.7%, and 32.2% respectively compared to before storage. The precipitation during the high water level period after storage changed the most, while the precipitation during the flood season changed the least.