Surface Deformation Detection of the Moraine Dam of the Longbasaba Lake in Tibet of China Based on PS-InSAR Technique and Associated Influencing Factors
Surface deformation of a moraine dam is usually used as an estimation of its stability.For the deformation monitoring of moraine dam in alpine region,the technology of Synthetic Aperture Radar(InSAR)still has some technical defects in spite of its popularity,while the application of remote sensing technology based on Persistent Scatterer Interferometric Synthetic Aperture Radar(PS-InSAR)has not been reported yet.Located at the border between China and India and Nepal,the Longbasaba Lake is exhibiting the high risk of moraine dam failure.In this study,based on 75 Sentinel-1A images and PS-InSAR technology,it analyzed the dynamic deformation of the moraine dam of the Longbasaba Lake from February 2017 to April 2023.(1)In 2017-2023,there was a tendency for the Longbasaba Lake dam to subside at an average deformation rate of-2.76±0.66 mm/a.The distinct surface subsidence place in the dam was mainly distributed along the lake bank,accounting for 43.3％of the total surface area of the dam body,with an average subsidence rate of 16.82±1.55 mm/a.In the middle of the dam,there was a noticeable subsidence zone transversally running southeast-northwest,with the maximum deformation permanent scattering point(PS point)at-81 mm/a.The central dam suffered an uplift,with an uplift area accounting for 9.8％of the total area of the dam body.The average uplift rate was 17.38±2.43 mm/a,and the maximum deformation PS point deformation rate reached 43.90 mm/a.On the outer edge of the dam,the deformation rate was relatively low,fluctuating within-4～4 mm/a and an average deformation rate of 0.53±0.23 mm/a,accounting for 41.11％of the total.(2)In 2017-2023,the subsidence area in different months in a year accounted for 39.1％～65.8％,among which the subsidence size in July was the largest,accounting for 65.8％of the total,whereas the uplifting area accounted for 22.3％～38.3％of the total area,with the largest one occurred in February.(3)Surface deformation of the moraine dam of the Longpasaba Lake had a close connection with some geo-physical settings,including the surplus of annual revenue and expenditure of heat flux of the dam body,the variation of buried ice inside the dam body,and the freezing and swelling of the migrated internal water.The results above can be applicable in risk evaluation of moraine lake so as to provide a theoretical basis for the simulation of moraine lake outburst and disaster prevention and mitigation.
deformation monitoringsurface subsidencePS-InSARmoraine damthe Longbasaba Lake
万方数据
维普
