How big is the impact of the Three Gorges on the climate?

According to the assessment report of China Academy of Engineering, the Three Gorges Reservoir has a certain impact on the local weather and climate nearby, especially on the temperature above the water surface, but it has little impact on the temperature around the reservoir, with an impact range of less than 20 kilometers.

According to the Climate Assessment Report on Comprehensive Benefits of the Three Gorges Project issued by China Meteorological Bureau, after the impoundment of the Three Gorges Reservoir (from 2004 to 20 1 1 year), the temperature in most parts of the reservoir area has increased compared with that before impoundment (from 996 to 2003), and the annual average temperature is 17.9.

Experts from China Meteorological Bureau said that in recent years, the extreme weather and climate in the Three Gorges reservoir area and its surrounding areas are closely related to factors such as atmospheric circulation in East Asia, sea surface temperature changes on the Qinghai-Tibet Plateau and thermal anomalies, but not directly related to reservoir water storage.

In recent years, several severe droughts have occurred in the middle and lower reaches of the Yangtze River, such as Dongting Lake and Poyang Lake. Some people think that this has a lot to do with the impoundment of the Three Gorges. In Hunan Province and Jiangxi Province, the demand for the estuarine sluices of Dongting Lake and Poyang Lake is increasing.

Dongting Lake is an important storage lake in the Yangtze River, which has the regulation function of "holding four waters". For a long time, the Yangtze River water carried a lot of sediment into the lake, which led to the continuous deposition of sediment in Dongting Lake and the continuous shrinkage of the lake. "After the impoundment of the Three Gorges, a part of the sediment was intercepted, which made the discharged water clearer, which was very beneficial to alleviate the sediment deposition in Dongting Lake." Shen Guofang said, "At the same time, cutting the Yangtze River with clear water will have a more obvious scouring effect on Dongting Lake entering the estuary."

The situation in Poyang Lake is slightly different. Shen Guofang introduced that Dongting Lake and the Yangtze River exchange water with each other, but Poyang Lake is more leaking. During the impoundment of the Three Gorges every year, the discharge from the reservoir is lower than the natural discharge, and the water level of the main stream downstream of the dam decreases, which increases the discharge at the mouth of Poyang Lake.

The assessment report of China Institute of Engineering made a more detailed analysis: "The impact of the operation of the Three Gorges Reservoir on the utilization of resources in Dongting Lake and Poyang Lake is mainly manifested in the following aspects: during the post-flood storage and detention period, the water level of the main stream of the Yangtze River decreased, the amount of water entering Dongting Lake through the three ports in Jingnan decreased, the outflow of the two lakes increased, the dry season advanced, and the low water level decreased, which had a certain impact on irrigation, water supply and ecological environment water use."