Water will be transferred to Hangjiahu and Ningshao Plain, Shanghai and southern Jiangsu through canals to implement water and soil improvement projects in the whole basin.

12.4.2. 1 Diversion of Qiantang River to quench thirst in the Yangtze River Delta.

As mentioned above, the fresh water flowing into the sea from the mouth of Qiantang River is about 380× 108m3 every year. According to the normal water level, the Hangzhou Bay Ecological Reservoir can store about 400× 108m3 of water. Therefore, after the completion of the reservoir, under the condition of maintaining the normal water level in Hangzhou Bay, water can be transferred from Hangzhou Bay Reservoir to the plain of northern Zhejiang, southern Jiangsu, Shanghai and Ningshao where water resources are in short supply and water quality is deteriorating (300 ~ 400) ×108m3; To the north, you can cross the Beijing-Hangzhou Canal, Taihu Lake and Taipu River and reach the Huangpu River. To the south, water can be diverted to Ningshao Plain through Hangzhou-Ningbo Canal, connecting Cao 'e River, Yaojiang River and Yongjiang River to the mouth of Yongjiang River and entering the sea through Xiaoshan and Shaoxing. In this way, the "Hangzhou Bay Reservoir" has become an interconnected water conservancy hub system with the plain river networks in northern Zhejiang, southern Jiangsu, Shanghai and eastern Zhejiang, which can not only adjust the water level in the Hangzhou Bay reservoir area, but also control the static by dynamic control, and wash away the fishy smell of the canal, Taihu Lake, Caoejiang River, Yaojiang River and Yongjiang River with the continuous river water of Qiantang River. At the same time, the surrounding environment of "Hangzhou Bay Reservoir" will be comprehensively treated to make it an ecological reservoir with good water quality. The canal, Cao 'e River, Yaojiang River, Yongjiang River and even Taihu Lake will be dredged, revetment and sewage interception will be carried out, the use of highly toxic and residual pesticides and fertilizers will be restricted, and industrial "three wastes" and domestic sewage will be prohibited from being directly discharged into rivers (lakes). The implementation of such a huge basin-wide water and soil reconstruction project can not only basically eliminate the water and soil pollution accumulated in the plains of northern Zhejiang, Shanghai, southern Jiangsu and eastern Zhejiang for many years, stop sewage irrigation and turn green oases, but also solve major problems such as water pollution that has been plaguing Taihu Lake Basin because of poor water circulation, and the ecological environment of the whole Yangtze River Delta region will benefit from it. In this way, there is no need to build the water diversion project of Qiandao Lake Reservoir in Xin 'anjiang River, which can fundamentally solve the water shortage problem in Hangjiahu Plain and greatly alleviate the water shortage problem in southern Jiangsu and Shanghai. The construction of "Hangzhou Bay Reservoir" will form a positive interaction with the Hangzhou-Ningbo Canal Reconstruction Project being implemented in Zhejiang and the soon-to-be-launched East Zhejiang Water Diversion Project (Hangzhou-Ningbo Canal Reconstruction Project started in 2002, with an investment of 2.5 billion yuan, a designed channel depth of 2.5m, a navigable width of 45m and a total length of 252km, and is scheduled to be completed in 20 10), which will make the water in the East Zhejiang Plain

12.4.2.2 Curbing land subsidence disasters

The construction of such a super-large reservoir will not cause any adverse impact on the geological and ecological environment, and the huge amount of fresh water stored in Hangzhou Bay Reservoir is likely to infiltrate into the underground on both sides of Hangzhou Bay to form natural recharge, raise the groundwater level, improve the groundwater environment, and eliminate soil waterlogging and salt water intrusion. Especially in Hangjiahu Plain, South Jiangsu, Shanghai and Ningshao Plain, after solving the problem of domestic and industrial water use, the exploitation of groundwater can be stopped, thus effectively restraining land subsidence and restoring a benign ecological environment.

12.4.2.3 Eliminate tides forever, and add thyme oasis.

The tidal bore in Qiantang River is fierce, and the tidal tragedy occurs almost every year. The intertidal zone is long, which has many adverse effects on moisture prevention, flood control and utilization of fresh water resources. As Mr. Wang Huzhen, former chief engineer of Qiantang River Seawall Engineering Bureau, pointed out, "This tidal bore does more harm than good. If the ancients hadn't built winding seawalls on both sides of the Qiantang River, the plains of Hangzhou, Jiaxing, Lake, Ning and Shao would have turned into beaches long ago. Where can we live and work in peace today? " Therefore, the elimination of tidal bore and the realization of "Haining, Hu Ping" are the common aspirations of Zhejiang people in past dynasties. The construction of "Hangzhou Bay Ecological Reservoir", the increase of 1 10,000 hectares of Pinghu, the planting of trees and grass on both sides of the river and hundreds of miles of oases will also provide habitats for rare and endangered wild animals. The beautiful natural environment that Zhejiang sages dreamed of when they set up Pinghu and Haining will become a reality. In addition, even as far as tidal observation of Qiantang River is concerned, once the Hangzhou Bay Cross-sea Bridge, Shanghai Luchaogang-Yangshan Cross-sea Bridge (37 kilometers long) and the planned Shaoxing Cross-sea Bridge are completed, the tidal bore of Qiantang River will be difficult to reproduce.

As for the issue of Jiaxing Zhapu Port on the north bank of Hangzhou Bay, even if the dam is not built, as long as the Hangzhou Bay Cross-sea Bridge is completed, Zhapu will only become a transit point for many merchants, and the current advantages and functions of Zhapu Port will disappear in an instant. If you build a seawall, you can consider re-planning and build a new "Zhapu Port" outside the dam.

Some people may worry that after the completion of the Hangzhou Bay Ecological Reservoir, the original drainage works on both sides of the Qiantang River estuary will fail. We believe that, on the contrary, the construction of "Hangzhou Bay Ecological Reservoir" will not have a negative impact on the original drainage project, because the water levels of the canals on both sides of Qiantang River (Beijing-Hangzhou Canal and Hangzhou-Ningbo Canal) can be adjusted through Hangzhou Bay Ecological Reservoir, which can not only discharge water to the sea through the sluice of the dam in rainy season, but also transfer water from Hangzhou Bay Ecological Reservoir to Beijing-Hangzhou Canal and Hangzhou-Ningbo Canal in dry season, thus solving the problem of poor navigation of the canals in dry season. On the other hand, if the "Hangzhou Bay Reservoir" is completed, it should also be listed as a part of the national "South-to-North Water Transfer Project". By then, the whole drainage project can be re-planned from the perspective of system engineering, rather than sticking to the original drainage project.