都江堰水利系统的地球科学思想

岷江中游的都江堰水利系统为256BC战国时代蜀郡太守李冰主持修建,经长期发展完善,至今仍发挥着巨大的作用,为世界上使用历史最长的古老水利系统.该水利系统利用岷江由上游山区进入中游平原的自然条件,根据河流地质作用的原理,因地制宜,因势利导,修建了分流、泄洪、治沙和引水等工程,达到了灌溉、防洪和通航的目的.而且,设置了相应的监测设施,确立了维护制度,营造了我国西部地区最大的水田农业生态区,与岷江上游山地森林生态区组成森林-水田农业生态系统.

GEOSCIENTIFIC THINKING OF DUJIANGYAN WATER CONSERVANCY SYSTEM

In 256 BC, Li Bing, the Magistrate of Shu Prefecture ( ancient name of the western Sichuan Basin), managed to build up the Dujiangyan water conservancy system, that is the unique large water conservancy construction in the world, which has been built up before the Christian era and continue to be used for more then 2 200 years. Now it makes the most of the water conservancy works. Dujiangyan water conservancy system has been built up along the middle reach of the Minjiang River in the Chengdu Plain. Both of the Minjiang River and the Chengdu Plain have been developed by erosion and deposition of rivers for lift up of the eastern Qinghai Xizang Plateau since the later stage of the Middle Pleistocene. The Minjiang River has the largest discharge of river within Sichuan Basin, which may supply the development of civilization on fertile land in the Chengdu Plain with abundant water resources, in turn, the 80% of discharge of the Minjiang River is concentrated in the period of May to October, that may result in big floods on the Chengdu Plain. Three major projects in the canal head area of Dujiangyan have been built up in the joint of the middle reach sector of the Minjiang River with the upper reach sector. Yuzui Watershed Weir at the front point of central bar divides the river into two currents along Neijiang River and Waijiang River respectively, the former directly to the Chengdu Plain, and the latter discharges the superfluous water. Feishayan spillway built at the convex bank of the Neijiang River may keep a right level of water for the current. Especially, over the Spillway, the water flow in form of circular motion and vortex may send sands and blocks from the Neijiang River into the Waijiang River. Baopingkou excavated at the south part of the Yulei Mountain, is an especial way which leads and controls the current to the Chengdu Plain. More, three channels have been excavated as major canals for irrigation, shipping et al . on the Chengdu Plain. Among them, two channels join together at Chengdu and flow on into the Minjiang River, which makes the city develop into a great metropolis. Significantly, several ancient hydrologic measurement marks have been made in conservancy projects, and the annual repair engineering institution has been set up. These projects not only have been used as an effective water conservancy installation, but also scientifically solved the headachy problem of aggradation in water conservancy construction. It is believed that important principle and idea about water control have been understood in that time. Based on principles of geological action of river and hydrodynamics of river, such as erosion and deposition, channel feature and channel process et al ., Li Bing made the best use of advantage of natural conditions and avoided harm of disadvantage of them, which spur Dujiangyan to constructs and to develops a forest paddy field ecological environment system, including forest area along the upper reach of the river and paddy field agriculture area on the Chengdu Plain, and to create and to bring up the "land of abundance" of Sichuan. Li Bing is a great ancient scientist and engineering export.$$$$