Analysis Of The Area Change And Driving Force Of Dabson Lake

Groundwater in the inland basin of the northwest is formed in the mountains,with runoff in the plains and disappearing into the desert or terminal tail lake.Lakes are an important element in maintaining ecological balance.As an important part of the water resources in the arid and semi-arid regions of the northwestern inland,the expansion and shrinkage of the lake and its ecological and environmental problems can reflect the changes in the climate characteristics of the study area and the response of human engineering activities.Located on the southern edge of the Qaidam Basin,Dabson Lake is under the jurisdiction of Golmud City and is the largest saltwater lake in the basin.As a typical terminal tailing lake in the inland arid region of northwest China,its area change and driving force research have guiding significance for the study of other lakes in the northwest inland basin and the protection and utilization of water resources.Based on the 1987-2017 Landsat TM and Landsat OLI remote sensing data,this paper uses the improved normalized differential water index method(MNDWI)to calculate the lake area of Lake Dabson.From the perspective of driving force,based on field investigation,combined with natural factors and human engineering activities,the area change of Lake Dabson was explored.Finally,under the ecological constraints,the numerical simulation method was used to simulate the impact of lake water flow into the lake under the future exploitation of groundwater.Based on the above research,we can draw the conclusion that:(1)The Lake Lake area of Dabson Lake has a three-stage change trend,that is,"first decrease,increase,decrease".In 2002,the lake area was the smallest,177.957km2;in 2011,the lake area was the largest,reaching 452.56km2.(2)In the past 30 years,the annual average rainfall of Golmud City is only 44.5mm,and the flow of water to the Lake of Dabson is negligible.Evaporation is the most direct way of excretion of lake waters.The annual evaporation of Dabson Lake decreased with the increase of lake area,and there was a significant negative correlation between the two.R2=0.93.This shows that evaporation is an important cause of fluctuations in lake area.Changes in temperature and glaciers can cause changes in the runoff of the Golmud River,resulting in changes in the flow into the lake.The increase in temperature accelerates the melting of snow and ice in the mountains,resulting in an increase in the annual runoff of the Golmud River,which in turn increases the area of Lake Dabson.Both showed a significant positive correlation,R2=0.82.This also verifies that the Golmud River runoff is the only surface source of lake-to-lake flow and one of the important factors leading to changes in lake area.(3)The remote sensing interpretation of Yantian area from 1987 to 2017 shows that with the increase of population,human engineering activities have increased the exploitation and utilization of salt fields,resulting in shallow backwater supply to the groundwater,resulting in shrinking lake area.Therefore,human engineering activities are one of the important factors leading to the reduction of lake area.(4)In order to maintain the minimum lake area of 177.957km2 in 2002,the minimum flow into the lake of Dabson Lake should be 2.81×108m3/a,which means that 2.81×10 m3/a is the threshold for the flow into the lake.(5)By analyzing the annual runoff of Golmud River and the impact of human groundwater exploitation on the change of Dabson Lake area,it can be seen that the influence of Golmud River runoff on the change of Dabson Lake area is greater than that of human groundwater exploitation.(6)The current situation of simulation(2017,23.4×104m3/d),recent(2020,41×104m3/d),and long-term(2030,66×104m3/d),the impact of groundwater exploitation on the flow of lakes into the lake,the annual flow into the lake is 3.61×108m3/a,which is greater than the minimum requirement of 2.81×108 m3/a;the recent(2020)flow into the lake is 3.11×108m3/a,which is greater than the minimum requirement of 2.81×108m3/a;In 2030,the flow into the lake is 2.58×108m3/a,which maintains the area of Dabson Lake,which is 163.3km2,which is less than the minimum requirement of 2.81×108 m3/a and the requirement of 178km2 of Dabson Lake.Groundwater exploitation has an impact on maintaining the flow and area of Dabson Lake into the lake.Under the condition of mining strength of 600,000m3/d,the flow into the lake is 2.85×108m3/a,which is greater than the minimum requirement of 2.81×108m3/a into the lake.That is,600,000m3/d is the optimal production amount.