Temporal And Spatial Variation Of Ecological Base Flow Value In Guanzhong Section Of Weihe River Mainstream

The global risk report of the World Economic Forum lists the water crisis as the most serious risk in the world.As the basic flow of river ecosystem to healthy and sustainable development, ecological base flow is of a good value that has certain practical significance to the water crisis.The study of ecological base flow has been widely carried out at present,especially in recent years, the national major science and technology water special project has made a lot of research results, but the research on the ecological base flow value or it's temporal and spatial changes is relatively small. In view of the phenomenon that ecological base flow is difficult to guarantee and its value did not paid much attention in water resource shortage area, In this paper, the temporal and spatial changes of the ecological base flow value in Guanzhong Section of Weihe River mainstream are studied as an example. And the compensation based on the ecological base flow security has carried on the preliminary research. The main achievements are as follows:(1) Adopted two methods to estimate the ecological base flow value of each river i Guanzhong Section of Weihe River mainstream, the results of the two methods are compared with each other, then the spatial variation of the ecological base flow value is obtained preliminary. That is: the ecological base flow per cubic meter value of four sections in their own control section is gradually decreases from upstream to downstream by comprehensive estimation method, which are about 5.74 yuan per cubic meter and 3.83 yuan per cubic meter and 2.29 yuan per cubic meter and 2.16 yuan per cubic meter. And the result of subentry estimation are: 5.31 yuan per cubic meter and 3.46 yuan per cubic meter and 2.60 yuan per cubic meter and 2.25 yuan per cubic meter. The difference between the two estimation methods is small, and the ecological base flow per cubic meter value in general is decreasing from upstream to downstream.(2) Estimated the effect weight of the ecological base flow value of each river in Guanzhong Section of Weihe River mainstream at 2001 to 2012 years by using variation coefficient method , Then according to the ecological base flow value in 2012, combined with the relative effect weight that compared with 2012, obtained the interannual changes law of ecological base flow value in Guanzhong Section of Weihe River mainstream at 2001 to 2012 years preliminary. That is:the interannual variability of the ecological function value of the Baoji section, the Xianyang section, the Xi'an section and the Weinan section of the Weihe River mainstream are increasing year by year, Xi'an and Baoji section are rise faster, Weinan and Xianyang section are basically flat; The ecological base flow value of four sections are fluctuating changes, of which Baoji section fluctuates greatly, followed by Xi'an , Weinan and Xianyang section, the chages of these three sections' base flow value are basically flat, but the value of ecological base flow is basically the highest in Baoji section, Xi'an section is the second, Xianyang and Weinan section are the smallest. The trend of value of ecological base flow per cubic meter are also fluctuating changes, Baoji section fluctuates greatly, Xi'an Xianyang and Weinan sections' fluctuation are small, They are all growing slowly, As a whole,the ecological base flow per cubic meter value is increasing year by year and gradually decreasing from upstream to downstream.(3) Applied water supply price elasticity model to a typical year to study the ecological base flow value changes in years, Then obtained the relationship between the value of ecological base flow and the satisfaction of base flow and runoff preliminary, finally we found that the ecological base flow value decreases with the increase of runoff when the ecological base flow is satisfied; But when the ecological base flow is not satisfied, the value increases with the increase of runoff ;The value of the ecological base flow is not only related to the runoff, but also to the satisfaction of the base flow .(4) Preliminary estimated the total ecological base flow compensation of each river in Guanzhong Section of Weihe River mainstream from 2001 to 2012 years. Finally concluded that the shortage of ecological base flow in Baoji was the highest, and the compensation amount was 20,243, 37, 7, 17, 38, 3, 22 million yuan respectively in the year of 2001, 2002,2003, 2005, 2006, 2007, 2010,2011.And the amount of compensation was 31,10 and 10 million yuan respectively in the year of 2001, 2002, 2003 in Xianyang. The ecological base flow in Xi'an section was satisfied ,so the compensation was 0; The ecological base flow is shortage only in June 2001 in Weinan, the compensation was 16 million yuan.