Seite - 214 - in Book of Full Papers - Symposium Hydro Engineering

3. OBSERVATION AND ANALYSIS OF THE THREE GORGES RESERVOIR 3.1. CHANGE OF METEOROLOGICAL ELEMENTS Through the analysis of local climate monitoring system, we found that after the Three Gorges Reservoir construction, the average annual precipitation in the reservoir area decreased, but the difference was obvious every month. The precipitation in June and July decreased compared with that before storage, while in August and September, it increased slightly compared with that before storage. The precipitation days of each station in the reservoir area decreased after the storage, but the number of annual rainstorm days increased, the intensity of precipitation in the reservoir area became larger and the frequency of extreme precipitation increased. Figure 1: Comparison of annual mean value of meteorological elements Compared with pre storage, annual mean temperature, maximum temperature and minimum temperature were significantly increased, the average annual temperature of temperature rise in the area between 0.1℃～0.4℃, especially in the seasons of spring and autumn warming significantly, but the change is not obvious in summer temperatures. In addition, after the completion of the reservoir, the annual evaporation amount increased slightly, but the change trend was not significant; the annual relative humidity decreased, the annual fog days decreased, and the change trend was significant. 3.2. The Three Gorges reservoir has a regulating effect on the local climate after the storage of the Three Gorges reservoir, and the effect of cooling in summer and Warming in winter is obvious In order to analyze the impact of the Three Gorges Reservoir on the small climate, the near reservoir area and the far reservoir area are divided according to the distance 214