杭州西湖初次换水观测结果的解释

为了适应杭州市旅游事业发展的需要,市政府开凿燧洞,引钱塘江水更换西湖湖水,改善西湖水质。湖水质量变差的主要原因是水中有机质和矿物质增加,即矿化度增高所致。而水的矿化度与其视电阻率呈近似线性关系,因此,对更换湖水的监测可用视电阻率法。从绘制出水等机电阻率图可以了解更换水(混合流)的动态变化;由于湖水物质浓度及其视电阻率变化遵守无限稀释作用规律,即负指数衰减规律,因此,可建立数学模型,从理论上揭示混合流的运动规律。最后,文章还从实测结果和数学模型出发,探讨了经济合理的换水方法。

THE INTERPRETATION OF THE OBSERVATIONSON THE FIRST WATER-CHANGING WORK INTHE WEST LAKE, HANGZHOU

In order to suit the needs of the rapidly developing tourism in Hangzhou and improve the water quality of the West Lake, the Hangzhou Municipality hewed a tunnel and diverted water from the Qiantangjiang River to the West Lake to replace the original water in the West Lake.The worsening water quality of the lake is mainly attributable to the increasing organic substances and mineral matters in water, i. e., the increase in mineralization intensity of the water. The mineralization intensity of water, however, is approximately in linear relationship with its apparent resistivity. Therefore, we can use the apparent resistivity method to monitor the water-changing Work. From the equi-apparent resistivity graph of water that has been drawn, we can know the dynamic variation of changing water, i. e., the shape of mixed flow. As the concentration of substances in lake water and the variation in apparent resistivity obey the infinite dilution law, namely, the negative exponent attenuation law, we may establish a methmatical model and thus reveal the motion law of mixed flow theoretically.Based on the observation result and mathematic model, this paper also makes a tentative discussion on the economical and reasonable water-changing method.