Research On The Combined Effect Of Daihai Ecological Water Demand And Ecological Water Replenishment

Ecological water demand is an important indicator of lake ecosystems,maintaining a virtuous cycle of lake ecosystems.Ensuring lake ecological water demand can not only meet the requirements of the healthy development of the lake ecosystem,but also conform to the requirements of my country’s new development concept,which is an indispensable link in my country’s long-term development.In recent years,the phenomenon of lake shrinkage has been obvious,and the ecological environment has been seriously damaged.It is of great significance to ensure the normal evolution and development of lakes through ecological replenishment of lakes with insufficient water requirements.Taking Daihai,a semi-arid lake in central Inner Mongolia,as the research object,the dynamic ecological water demand of the lake is analyzed,and the water supplement plan is set and evaluated according to the water demand to provide a theoretical basis for actual construction.On the basis of remote sensing and meteorological data,the interpreting images obtain long-term series of high-precision hydrological element data from 1975 to 2020,and analyze the temporal and spatial evolution of hydrological elements in Daihai;through natural ecological water level analysis method,water level empirical frequency analysis method,biological The spatial minimum demand method and the lake morphology analysis method analyze the key water depths of the Daihai water level changing with the area;construct a lake ecological water demand model based on the ecological water consumption law to calculate the dynamic range of the Daihai ecological water demand under natural conditions;according to the planning goal,Design and select an ideal Daihai water replenishment program;determine the ecological water replenishment evaluation indicators through multiple aspects,build a model with the help of fuzzy analytic hierarchy process,conduct program evaluation,and select the best program.The results of the study are as follows:The area of Daihai Lake has shown a significant decline in the past 45 years.The area of the lake has decreased by 67.54%,and the area decline rate is 2.3 km~2/year.If this rate continues to develop,it is expected that Daihai will completely dry up in 20years.However,in recent years,it The rate of decline is slower.The water quality has been poor for many years,and the water quality on the south bank is worse than that on the north bank.In natural years,the suitable ecological water demand of Daihai is397-696 million m~3 in the dry season and 61-964 million m~3 in the wet season.The average annual ecological water demand is 562-771 million m~3;The corresponding suitable lake area of Daihai Lake is 59.98-79.8 km~2 in the dry season,74.1-97.57 km~2in the wet season,and the average annual suitable area of the lake is 70.92-84.77 km~2;According to the planning goal,six reasonable replenishment schemes are set up.The best replenishment scheme is evaluated to replenish 2 million m~3 from Yongxing Lake to Daihai within the year,and the replenishment flow from the Yellow River to replenish Daihai is 2.16 m~3/s.Water replenishment for 180 days in the year.This method is used to provide ecological water replenishment to Daihai.By the 2030planning year,Daihai’s area will be approximately 69.59 km~2 and its water volume will reach 542 million m~3,which is close to Daihai’s ecological water demand and suitable lake area.Ecological planning requirements.By determining the ecological water demand Daihai dynamic range can achieve real-time monitoring of the ecological health of the lake,and to determine the optimal ecological water supplement program that can provide a scientific basis and operational guidance related to planning and management,so as to provide for the lake.