Vulnerability Assessment Of Glacier System In Shiyang River Basin

Glacier is an important water resource in arid inland river basin.Climate warming is bound to cause severe shrinkage of glaciers and have an important impact on water resources and ecological environment of the basin.Shiyang River is one of the three inland rivers in Hexi corridor.Ice and snow melting water in alpine area is an important form of water resources for production,life and ecological environment maintenance.Affected by the global climate change,the glacier retreat in Shiyang River Basin is serious,which leads to the decrease of melt water runoff,directly affects the water resources of the basin,and has a negative impact on the ecological environment security of the basin.In the context of climate change,it is of great practical significance to carry out the study on the vulnerability assessment of the glacial system in Shiyang River Basin,clarify the current situation of glacial change,determine the driving factors of glacial change,and then establish the vulnerability assessment index system to assess the vulnerability of glaciers in Shiyang River basin,so as to provide reference for coping with climate change and water resource management in Shiyang River Basin.Based on the satellite remote sensing data and meteorological data,this paper studies the glacier change and vulnerability assessment of Shiyang River Basin,which is very fragile in ecosystem.The main work includes:(1)using GIS and RS technology combined with artificial visual interpretation,extracting the glacier boundary information of five remote sensing images of 1995,2002,2009,2015 and 2016,combining with the existing glacier data of 1973,dividing into This paper analyzes the glacier changes in Shiyang River Basin in the past 45 years;(2)according to the extracted glacier information,combined with DEM data,extract three terrain factors:slope,orientation and elevation.Based on the method of correlation analysis and geographical detector,the correlation between glacier change and terrain factors is analyzed,and the spatial dependence between glacier change and terrain factors is explored;(3)VSD function model is established based on the three elements of glacier change vulnerability(exposure,sensitivity and adaptability),and the vulnerability of watershed glacier system is synthesized by spatial principal component analysis Evaluation.The key factors affecting the vulnerability of glacier system are determined,and the relationship among sensitivity,exposure and adaptability of glacier system is analyzed.The results show that:(1)The annual average area change rate of glaciers in Shiyang River basin changed from-1.27%·a~-11 in 1973-1995 to-2.87%·a~-11 in 2015-2016.The scale of glaciers in Shiyang River Basin is small,with the largest area of 3.16 km~2 and the smallest of 0.06 km~2.The terrain controlling factor of glacier ablation is mainly the direction,and the south facing sunny slope accounts for the majority in quantity,which is directly related to the amount of solar radiation.(2)The slope,orientation,the highest altitude and the lowest altitude explain the spatial differentiation of glaciers in different degrees.Altitude is the most important controlling factor for spatial differentiation of glacier change,followed by orientation and finally slope.The interaction of any two terrain factors on glacier change is larger than its superposition,which belongs to nonlinear enhancement relationship.The interaction of the two factors,the highest altitude and the orientation,has a great influence on the spatial differentiation of glaciers.Because the orientation of glacier is closely related to solar radiation,altitude and temperature,the different terrain conditions lead to different glacier development.(3)From 2002 to 2015,the vulnerability of glacial system in Shiyang River basin gradually increased,and most of the study areas were in severe vulnerability and extremely severe vulnerability.Among them,the eastern region has low altitude,high vulnerability level and relatively large glacier fragmentation.Compared with 2002,the area of potential vulnerability decreased by 15%in 2009;compared with 2015 and 2009,the area of potential vulnerability decreased by 3.79%,while the area of severe vulnerability increased by 16.46%.(4)The vulnerability of glaciers is affected by a variety of comprehensive factors,the most important influencing factors are glacier orientation,slope,maximum altitude,glacier thickness,temperature,area and glacier type.Glaciers are very sensitive to climate change.Temperature and precipitation change affect the vulnerability of glaciers in different scales.The vulnerability degree of glacier system mainly depended on the exposure degree of glacier terrain,the sensitivity of glacier thickness,and the adaptability determined by glacier scale and type.In 2002 and 2015,glacier thickness contributed the most to Glacier vulnerability,followed by climate factor and terrain factor,and finally glacier type;in 2009,glacier thickness contributed the most to Glacier vulnerability,followed by terrain factor,and finally area.Generally speaking,the influence of terrain factors on glacier change is an important aspect that can not be ignored.Terrain factor is the main factor controlling the energy balance of glacier surface driven by climate factor.The vulnerability of glaciers belongs to dynamic change,and the factors affecting the vulnerability in different periods of time also change with the change of external driving forces;there are differences in the vulnerability of glaciers,and each evaluation index has different contribution rate to the evaluation results,and the contribution rate between each index is relatively small.Glacier thickness is the most important factor affecting the vulnerability of glacier system.