科学需要争论，但这绝不能成为一小撮别有用心的家伙造谣污蔑国家发展借口。看到有人打着博士的头衔造谣污蔑我国刚刚开通的南水北调工程，我写了一篇揭露其愚蠢无知的网文。很多科学网的网友，表示支持，但也有些人并不认同。不过，《中国日报》则认为此博文对揭露谣言很有说服力。

一些人把科学网的博客当成自己交流感情，散心消遣的后花园，在这里拉帮结伙，自娱自乐。他们似乎不希望有人在这里揭露谣言，传播科学和事实。但是，我们有责任感的科技工作者则要就是要把这里当成弘扬科学精神、揭露谣言、维护国家发展的一块舆论征地。

Rumors over water projectdestructive

By Zhang Boting (China Daily)Updated:2014-12-25 07:48

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The South-NorthWater Diversion Project is expected to begin supplying water to Beijing by theend of this week, but rumors are doing the rounds that the capital may have towait longer for water from South China because the central route canal hasfrozen.

In a widelycirculated blog posting, an "observer" claims to have noticed the"slow flow" in the central route canal, saying this could preventwater from reaching the capital in winter. The "observer" also sayssilting could damage the canal.

The blogger'sclaims are absurd, to say the least. The blog posting says the central canalwill transfer water at the rate of 22.4 cubic meters per second, or one-tenthof the designed capacity, because a China Central Television news video shows aRubber Duck moving 10 centimeters per second in its water.

People with eventhe basic knowledge of physics know that the velocity of a floating object isnot equal to that of water, because the former meets resistance from the latterfrom below and air from above. Besides, the water velocity varies with depth -a river that is calm might have fierce currents flowing below the surface. Arough calculation shows a speed of 10 cm per second means 8 kilometers in 24hours. If the canal water indeed travels at such a slow pace, as the blogposting claims, the water should not have crossed South China even today.

The fact,however, is, water in the canal reached Zhengzhou, Henan province, in CentralChina earlier this month, three days after the project's central route wasopened and flowed into Hebei province in North China a few days ago. Does theblogger know these facts?

The South-NorthWater Diversion Project's ultimate aim is to transfer 44.8 billion cubic metersof freshwater northwards from the Yangtze River every year. The eastern routecanal will transfer water through Jiangsu, Zhejiang, Hebei and Shandongprovinces, the central route to Beijing and Tianjin, and the western route toShanxi, Shaanxi, Gansu and Qinghai provinces and the Inner Mongolia and NingxiaHui autonomous regions.

The blogger'sconcern over silt, mainly deposits of mud and sand, appears a little morereasonable, though, because it is unavoidable given the relatively slow flow ofwater in the Danjiangkou Reservoir in Hubei province, a major source of waterfor the project. But this problem is confined to the Danjiangkou Reservoir,because the flow of water in the central canal will ensure that it is notplagued by silt. Thus, there is no need to worry about the canal being damagedby silt.

Even the silt inthe Danjiangkou reservoir is nothing serious. The reservoir, built in 1958, isa multi-purpose facility that serves as a major source of water for the region,generates electricity and controls floods. Since the canal that supplies waterto power plants is situated at a lower altitude than the one which supplieswater to the south-north project, silt in the reservoir won't do any harm aslong as the hydraulic power plant functions normally.

Silting is anormal phenomenon, typical of all reservoirs. Every reservoir has a balancingpoint of silt deposits and the volume of water, and the Danjiangkou Reservoirreached that point long ago. The blog posting didn't consider this most basicprinciple.

According toproject authorities, the climate varies along the canal, which stretches 1,432km from South to North China, and the section north of Anyang in Henan provincecould freeze in the winter. It is estimated that the rate of flow in the canalwould drop by 40 percent because of the freezing on the surface - but that willnot affect the flow of water under the surface.

Concern over theSouth-North project is welcome, but spreading rumors is rather destructive.Once the water from the south reaches Beijing, rumors will die a natural death.

The author is asenior researcher at China Society for Hydropower Engineering.

本文链接：http://www.chinadaily.com.cn/opinion/2014-12/25/content_19163536_2.htm