The main reason why the water system doesn't work.

The South-to-North Water Transfer Project was built to solve the shortage of water resources in the north, not for flood control in the south. The flood control benefit of the South-to-North Water Diversion Project is mainly that the reservoir capacity is greatly increased after Danjiangkou heightening, which greatly reduces the flood control pressure of the Han River, but it is only limited to the Han River below Danjiangkou in Hubei Province. However, the Hanjiang River has just entered the flood season for one month. This year, the rain belt is south, and the upper reaches of the Han River are like water. Naturally, we can't see the benefits of flood control. In addition, the main purpose of the Middle Route and East Route of South-to-North Water Transfer Project in Shandong and North China is urban water supply, and it will only be supplemented when there is a lot of water for agricultural irrigation. Now that the two projects have just been put into operation, it is even more impossible to supply water to agriculture.

The East Route of South-to-North Water Transfer Project is currently supplying water to Shandong, and Taierzhuang Pumping Station has been pumping water to Shandong since April. Jiangsu has pumped 328 million water to Lake Rome for the first time this year, but the drought in Shandong is serious this year. It is estimated that the amount of water diverted from the Yellow River to Jiqing and the first phase of the Eastern Line into Shandong is terrible.

The central line is also supplying water. However, due to the heightening of Danjiangkou hub, it was accepted last year. There was no water storage in the flood season last year, not to mention the high water level of 170 meters. Now it has just entered the flood season, and the water quantity adjustment is not big. By mid-July, there was only 1 100 million. In August last year, Pingdingshan's emergency water supply was specially approved by the National Defense General.

These water transfers play a great role in ensuring water supply in cities along the route, but even if they are taken, they will be a drop in the bucket for agricultural irrigation water.

————————————————————

Water transfer projects such as the South-to-North Water Transfer Project are mainly aimed at solving the problem of uneven distribution of water resources in space, but the flood still has the problem of uneven time. Among the main flood control measures, such as dikes, flood diversion areas, flood discharge canals and controlled reservoirs, reservoirs are the main means to stop floods and promote benefits. The reservoir capacity must reach a certain proportion of floods to promote benefits in the dry season, otherwise it can only cut off peaks, and the Three Gorges will continue to vacate storage capacity and reserve flood control storage capacity after the peak. However, China is sparsely populated, especially in the central and eastern regions, and the basins and valleys suitable for building large reservoirs are overcrowded. In order to obtain flood control storage capacity, a large number of immigrants are often needed, and the storage capacity of reservoirs is generally tense. For example, at the beginning of Danjiangkou construction, more than 300,000 people were resettled, and another 382,000 immigrants were resettled for heightening the dam for the South-to-North Water Transfer Project.

The East Route of South-to-North Water Transfer Project draws water from the Yangtze River to the north, and is regulated by Hongze Lake, Roman Lake, Nansi Lake and Dongping Lake, with a total storage capacity of about 7.8 billion cubic meters. However, the flood control pressure of these shallow lakes in the plain is very high. Hongze Lake, Roman Lake and Nansi Lake themselves are tributaries of the Wiseyi River choked by the old Yellow River. In order to ensure the safety of flood control, the limited water level in flood season is low, so we can only store the pumped river water, but we can't use the water quantity of Huaihe River and Yishu Sihe River in flood season (of course, there are also water pollution factors). Because as far as the peak flow and flood volume of Huaihe River and Yishu Sihe River basins are concerned, neither the reservoir capacity nor the flow capacity of water transfer projects can alleviate the floods in the basins, but will increase losses due to high water levels.