Comparative Study On The Extraction Algorithms Of Glacier And Lake From The Tibetan Plateau Based On The GF-1 Satellite

With the warming of the climate and the intensification of human activities,global glaciers and lakes have undergone drastic changes in recent decades,which have had an important impact on the local environment.The Tibetan Plateau,as a densely-populated area of glaciers and lakes at low and mid-latitudes,has attracted the attention of scholars from all over the world.Because most of glaciers and lakes on the Tibetan Plateau are in remote areas with very high altitudes,it is difficult to carry out large-scale,long-term monitoring work on the ground.The effective use of remote sensing data to monitor the change of highland glaciers and lakes is a hot topic in current scientific research.With the development of remote sensing technology,satellite data with high spatial resolution are continuously applied to scientific research.However,due to the differences in the range of high spatial resolution satellite data and the traditional medium-resolution satellites such as Landsat,how to use high-resolution satellites to extract glacial lakes and improve their optimization algorithms is a scientific problem that needs to be solved.In this paper,high-resolution satellite remote sensing data are used to accurately monitor glaciers and lakes in the Zangser Kangri and its surrounding river basins.Focus on the extraction of glaciers and lakes.The main research results are as follows:(1)Combine the "global-local" idea with iterative self-organizing data analysis techniques to form the local ISODATA classification method.Using this method,the band threshold method and unsupervised classification method to experiment on the GF-1 data which cover the study area in different time.As a result,the local ISODATA classification method has better universality and higher detection accuracy and can provide support for monitoring glaciers on the Tibetan Plateau with high precision.(2)The normalized water index threshold method,the LBV image transformation method and the "global-local" iterative method were improved to make it suitable for the monitoring of water bodies on the Tibetan Plateau.The experimental results on the extraction of different types of lake boundaries in the study area prove that the "global-local"iteration method is more suitable for the high-precision monitoring of the Tibetan Plateau's water.(3)Use the optimal algorithm derived from this study to extract the boundary of glaciers and lakes in the study area from 1990 to 2015.Analyze the area's changes of glaciers and lakes in the study area.Combine relevant meteorological data to speculate on the main causes of changes in glaciers and lakes in this region.The results showed that the entire glacier continued to shrink,but the lakes first shrank and then expanded;the increasing temperature was the main reason for the retreat of glacier;the increase of precipitation played a leading role in the expansion of the lake.