Middle Route of the South-to-North Water Diversion Project
The South-to-North Water Diversion Project is the largest of its kind in the world with its eastern, middle and western routes measuring 4,350 kilometers in total and a massive network of these three vertical routes connecting four major rivers. The project is designed to divert the water resources between the south and the north, the east and the west for a relatively reasonable redistribution.
The middle route draws water from the Danjiangkou Reservoir, which is located in the middle and upper reaches of the Hanjiang River, a tributary of the Yangtze. The canal water runs through two provinces (Henan and Hebei) and two municipalities (Beijing and Tianjin). Phase I of the middle route started construction at the end of 2003, and water diversion officially began in December 2014.
The 1,432-kilometer middle route connects four river basins: Yangtze, Huaihe, Yellow, and Haihe, crosses 219 rivers that each have a drainage area of 10 square kilometers, including the trunk stream of the Yellow River, and runs beneath railways at 44 spots. A total of 571 road bridges have to be built over the main diversion channel. Of all the structures, the tunnel beneath the Yellow River is the largest, most technically demanding, and most complicated and difficult with the longest construction period for a single structure. Of all the provinces and municipalities along the middle route, Henan possesses the longest trunk line (731 kilometers), which implies the most onerous work and the largest number of relocated people.
The middle route can largely mitigate the water scarcity in central and northern China, improve the ecological and investment environment in the water-receiving areas, and promote their socioeconomic development. By 2021, Phase I had cumulatively provided 44 billion cubic meters of water to Henan, Hebei, Tianjin, and Beijing, effectively easing their over-exploitation of underground water, bettering their economic landscape, and creating remarkable ecological and environmental benefits.
During the "100+ Biodiversity Positive Practices and Actions Around the World" campaign held in 2021, the "protection and restoration of water sources in the middle South-North water diversion route, Danjiang, Henan" was selected to be one of the global model cases, out of 258 candidates from 26 countries.
南水北調中線工程
南水北調工程是世界上規模最大的調水工程，東、中、西線干線規劃總長度達4350千米，構成以“四橫三縱”為主體的總體布局，以實現中國水資源南北調配、東西互濟的合理配置格局。其中，中線工程從漢江中上游橫跨湖北和河南兩省的丹江口水庫取漢江水，輸水干渠地跨河南、河北、北京、天津4個省、直轄市，一期工程于2003年年底開工，2014年12月正式通水。
中線工程全長1432千米，溝通長江、淮河、黃河、海河四大流域，穿過黃河干流及其他集流面積10平方千米以上河流219條，跨越鐵路44處，需建跨總干渠的公路橋571座。其中，穿黃隧洞是南水北調工程中規模最大、單項工期最長、技術含量最高、施工難度最復雜的交叉建筑物。在中線工程涉及的省（市）中，河南省境內干線長度731千米，線路最長，建設任務最重，移民搬遷人數最多。
南水北調中線工程可極大地緩解中國中、北部地區的水資源短缺問題，改善受水區域的生態環境和投資環境，推動區域經濟社會發展。截至2021年，南水北調中線一期工程向豫冀津京累計調水超過441億立方米，有效緩解了地下水超采的局面，使經濟發展格局得到優化，并取得十分顯著的生態環境效益。
2021年9月，在“生物多樣性100+案例”全球征集與評選活動中，“河南丹江南水北調中線水源地保護與修復”案例，從全球26個國家的258個申報案例中脫穎而出，成功入選“生物多樣性100+全球典型案例”名單。
