Remote Sensing Monitoring And Characterizing The GLOFs Of Lake Merzbacher

Glacial lake outburst flood refers to the phenomenon that the glacial lake suddenly releases a large amount of water.Glacial lake outburst flood has the characteristics of strong suddenness,high flood peak flow,strong destructiveness,and wide spread.When the glacial lake bursts,it often causes landslides.A series of secondary disasters such as mudslides pose a huge threat to the safety of life and property of downstream residents and coastal infrastructure.The Merzbacher Glacier Lake,located in the border area between China and Kyrgyzstan,is a typical ice dam lake with a history of over 100 years of rupture.The first recorded rupture can be traced back to 1902.Frozen lakes break out almost every year.The outburst flood of the Merzbacher Glacier Lake has a serious impact on the Aksu region in Xinjiang,which is located downstream of it,causing heavy losses to the industrial and agricultural production and comprehensive management of the watershed in the Aksu region.As an important indicator of changes in the cryosphere,glacial lakes are extremely sensitive to climate change.Under the influence of global climate change today,it is of great significance to understand the changes in the characteristics of the Merzbacher flood and to find out the factors affecting its collapse through the reconstruction and analysis of its historical collapse flood,which is of great significance to ensuring the safety of people’s property in the Aksu region of Xinjiang and assisting the flood control in the Aksu region.Based on remote sensing and GIS technology,this paper reconstructs the critical water level and critical area of The Merzbacher glacial lake by using the hydrological data and multi-source remote sensing data provided by the hydrological station,analyzes the relationship between the water storage rate and the rout,and clarifies the flood change law.In order to provide assist for flood prevention and control in the Aksu region.Studies have shown that:(1)Since 1958,the critical area of glacial lakes has been represented in three different periods as a whole.From 1958 to 1980,the critical area of glacial lakes showed an increasing trend,and the historical largest critical area(4.1 km2)appeared in this stage.From 1980 to 1990,the growth rate of the critical area of glacial lakes reached the highest peak.At this time,the critical area of glacial lakes increased at a rate of0.15km2/a as a whole,and the growth rate was 30% higher than the previous stage,with an average area of 3.2km2 However,after 1990,the critical area of Merzbacher began to decrease gradually.In the past 14 years,the critical area of the Merzbacher Glacier Lake has been decreasing at an accelerated rate,with a significant downward trend.From 2004 to 2018,the critical area decreased at a rate of 0.2 km2/a as a whole.(2)The rate of glacial lake water level rise before the collapse of the Merzbacher glacial lake was significantly negatively correlated with the glacial lake water level.This means that the faster the water storage rate of the glacier lake is before the collapse,the lower the critical water level required for the collapse of the glacier lake is still established.That is to say,a higher glacial lake storage rate will increase the risk of glacial lake outburst,and the glacial lake water storage rate is still an important factor leading to the outburst of the Merzbacher glacial lake.(3)The melting of glaciers in the River Basin has intensified,and the outburst time of the Merzbacher Glacier Lake is advanced from August to July.The probability of occurrence in July is 75%.The flood interval and flood duration gradually shorten,and the flood peak flow shows a gradual increase trend.As the climate changes,the advance of the outburst time of the glacial lake will persist for a long time,and the harm caused by each outburst of the Merzbacher glacial lake will also increase.