Evaluation Of River Health In The Upper Reaches Of Shiyang River

The long-term development of human society benefits from the clean water resources and beautiful water environment provided by healthy rivers.However,with the rapid development of economy,the problems of water shortage,serious water pollution and deterioration of water ecological environment in many rivers are becoming more and more serious.Since 2016,the CPC Central Committee has made major reform plans to comprehensively implement the river chief system.The paper puts forward the strategies of "jointly focusing on great protection,not on great development" to promote the high-quality development of the Yangtze River Economic Belt and "jointly focusing on great protection,jointly promoting great governance" to promote the ecological protection and high-quality development of the Yellow River Basin.Strengthening river management and maintaining river health have become the vision of the whole society,and also the main task of water control in the new era.River health assessment is an important part of river management.It will provide an important basis for judging river health status,finding river problems and analyzing "etiology".It is of great practical significance to carry out river health assessment for maintaining river health and life.As we all know,The environment is vulnerable in Shiyang River basin.It is a typical example of inland rivers in northwest China that the upper reaches produce water,the middle and lower reaches consume water.Rivers are one of the most important resources in Hexi region.It supports more than 2 million people and nurtures important grain,seed,vegetable,fruit production bases and animal husbandry production bases in China.It is essential to maintain social stability in the Hexi Corridor region and ensure the ecological security of the new Eurasian land bridge.How to take the road of “ecological Priority and green development”? It is necessary to define the health connotation of the upstream mountain rivers and evaluate their health status and existing problems,which is also an important content of river health management.Therefore,the work was carried out,as following:(1)The river health assessment system was constructed.Based on the full investigation of the ecological environment and social service function in the upper rearch of Shiyang River basin,on the basis of reference in 2020China’s Ministry of Water Resources "rivers health evaluation guidelines(trial)",in2017 in Gansu province bureau "Gansu river health survey and evaluation technology outline(trial)",and more than 150 rivers health related literature at home and abroad,relatively independent river health indexes,build the river hydrology and water quality,aquatic habitat physical structure,and social service function of four criterion layer and index layer of 10 evaluation index system.Using the Delphi method,the weights of each index were determined through statistical analysis and sorting out the survey results.The comprehensive scores of river health were determined by means of interpolation calculation,graded scores and graded weights.(2)The rivers health are evaluated.Through collecting and analyzing the river historical data and remote sensing image data,the river health assessment in the upper reaches of Shiyang River was carried out in 2008 and 2018.The results showed that Donghe River(68.9),Zamu River(67.3),Huangyang River(62.2)and Gulang River(67.9)were in health status in 2008,Xihe River(59.0),Xiying River(59.0),Jinta River(57.1)and Dajing River(56.7)were in sub-health Status.In 2018,Donghe River(86.1)was in ideal condition,Dajing River(59.9)was in sub-health condition,other rivers are in healthy condition(Xihe River 67.4,Xiying River 66.5,Jinta River 67.3,Zamu River 74.1,Huangyang River 69.1,Gulang River 76.3).Through comparative analysis,the health scores of 8rivers were improved,and the health status showed an improvement trend.For example,the Donghe River from health to the ideal state,the Xihe River,Xiying River,Jinta River from sub-health to health.(3)The reasons of affecting river health were analyzed.The annual variation tendency rate of runoff,the index of fish conservation and the utilization rate of water resources were low,which resulted in the low health score of 8 rivers.The decrease of river runoff and fish species is mainly caused by human activities.In the late 1950 s,people explored for minerals,cut down trees,overgrazed and cultivated land in the mountains,as a result,soil and water loss is serious,runoff shows a downward trend,and the number of fish also decreases.For a long time,the contradiction of water use in Shiyang River basin is prominent,and the utilization rate of water resources is high,which leads to the low health score of river.Over the past 10 years,both natural and human factors have improved the health of rivers.The natural reason is that the ecosystem in the Qilian Mountains region is getting better and better under the background of warm and humid climate.The man-made reason is the integrated management of the Shiyang River basin,which for more than a decade,the capacity of water resources management has been greatly improved,and the ecological migration project has relieved the ecological pressure in water conservation areas.People are aware of the scarcity of water resources,more cherish and care for water resources.