Research On Ecological Water Requirement And Ecological Compensation Mechanism In Yongding River Basin

Affected by human activities and climate change,the natural runoff of the Yongding River Basin has been declining year by year,and the plain river sections have dried up or dried up,seriously restricting the sustainable economic and social development of the region.In 2016,the state began comprehensive management and ecological restoration of the Yongding River,and was committed to building a green ecological corridor of the Yongding River.In 2017,the Yongding River began to carry out ecological water replenishment,and the river’s natural characteristics were gradually restored in the dry reaches,but the actual amount of ecological water replenishment was much higher.As expected,the amount of seepage water in the plain river segment is seriously inconsistent with the theoretical value due to the long drying time,the sudden drop of the groundwater level and the desertification of the river bed.Therefore,this paper takes the Yongding River Basin as the research object,based on the analysis of the ecological and hydrological situation of the river basin,according to the ecological requirements and ecological water demand function of the Yongding River Basin,the ecological water demand of the basin is calculated,and finally the horizontal ecological compensation mechanism of the basin is established based on the cost-effectiveness.The main research contents and conclusions are as follows:(1)The ecological and hydrological situation of the basin was analyzed,and the variation characteristics of meteorological and hydrological elements in the basin were analyzed by the Mann-Kendall trend analysis method,the Mann-Kendal change point test method,and the Pettitt change point test method.Then the IHA-RVA method is used to analyze the 33 ecohydrological indicators of key stations from five aspects:flow,time,frequency,delay and rate of change.The results showed that the runoff trend of the main control stations changed significantly and abruptly occurred around 1983,and the runoff consistency was poor;more than 90%of the ecological and hydrological indicators were highly changed from 2006 to 2019 compared with before the abrupt change.The watershed is significantly affected by climate change and human activities.(2)The calculation of the ecological water demand of the Yongding River Basin is carried out,focusing on the seepage water in the plain urban section based on the recent ecological water replenishment data and the calculation of the leakage coefficient of each river section with the help of remote sensing images.The ecological water demand of the plain section is integrated into the ecological water demand of the river basin.The results show that the seepage coefficient of Mencheng Lake and Lianshi Lake is 10cm/d,and the seepage coefficient of Yuanbo Lake,Xiaoyue Lake and Wanping Lake is 60cm/d;The basic ecological environment water demand of the Yongding River Basin is 381.43million m3,and the target ecological environment water demand is 483.98million m3.(3)To study the ecological compensation mechanism of the Yongding River Basin,use the emergy method to calculate the unilateral water ecological value of Beijing and Tianjin,based on the ecological water deficit in the key section of the river basin,the cost and benefit were analyzed with agricultural water saving and external water transfer as the source of ecological water supply,to get he optimal ecological compensation scheme for the Yongding River Basin is obtained.The results show that the water ecological economic value of the rivers in Beijing and Tianjin are 0.97 yuan/m3 and 1.27 yuan/m3 respectively,and the water ecological economic values of Beijing and Tianjin based on the ecological water demand are 199.78 million yuan and 77.68 million yuan respectively;The best ecological compensation method is to use agricultural water saving as the source of ecological water supply.The specific compensation plan is that Beijing will supply Shanxi Province with 199.78 million yuan,Tianjin will supply Hebei Province with 77.68 million yuan,and the government will compensate Shanxi Province and Hebei Province with 12.11 million yuan,360.07 million yuan.