Reservoir Ecological Regulation Scheme Based On Restoration Of Degraded Grassland In Riparian Zone

To calculate the river ecological water demand cannot only provide basic guarantee for ecosystem maintenance,but also provide regulation basis for reservoir discharge.This paper takes the downstream watershed of Xilin River Reservoir as the research object,calculates the ecological water demand based on both the inside and outside of the river.Meanwhile,compares the changes of the downstream discharge hydrological situation before and after the construction of the reservoir.In order to achieve the goal of restoring river ecological flow and grassland in riparian zone,the reservoir ecological regulation schemes with different guaranteed rates are put forward.The main results are as follows:(1)Four methods are used to calculate the minimum ecological water demand of the river in the whole year.The results of historical discharge method,annual distribution method,RVA/IHA index method and DFM method are 12.858×10~6 m~3,7.905×10~6 m~3,8.273×10~6 m~3 and 6.486×10~6 m~3,respectively.The calculated results of DFM method are more scientific and practical.(2)High-resolution remote sensing images and digital elevation models taken by UAVs were used to extract the riparian zones under different landforms,and visual interpretation was used to correct the range of riparian zones.The correlation coefficient between the length of rivers and the area of riparian zones was 0.881(P<0.05).The Penman-Monteith method was used to calculate the ecological water demand of vegetation outside the river.The results showed that the ecological water demand of vegetation in the riparian zone was 141.812mm per square meter per year.(3)By using the method of variation range,the changes of hydrological regime of Xilin River natural runoff and downstream discharge after reservoir construction are compared intuitively.The significant difference between April and June is obtained by quantifying the changes of hydrological measurement value and significant counting.The degree of river health decreased from A1 to B2 after the water volume changed.(4)Based on the principle of water balance,considering the difference of precipitation in different hydrological years and different guaranteed rate of ecological water demand of vegetation.A suitable formula and scheme for reservoir discharge calculation of Xilin River are proposed.Furthermore,the discharge schemes under different scenarios are analyzed.