| As an important freshwater resource, the glacier and perennial snow leadto the water changein rivers and lakes,mainly supplied by glacier melt water,thus impact on the watershed socio-economic development and ecological env-ironment. However, global warming has prompted most of the glacier and peren-nial snowfield retreat, which not only affects the water supply, also induced geo-logical disasters such as landslides, floods,and posed a major threat to humanlifeand production. Since marine glaciers widely distributed in Linzhi, tograsp th-e glacier changes is very important to its long-term planning, water resource m-anagement and disaster prevention.By using two period Landsat data in an interval of13years,this researchextracted the spatial and temporal information of the glacier, perennial snowfi-eld and glacial lake changes in Linzhi by means of remote sensing technology,which is multi-temporal, efficient and macroscopic. It also analyzed the relati-onship between the changes of glacier, perennial snowfield and glacial lake inLinzhi and its surrounding environment through the utilization of the spatialanalysis function of GIS and geostatistics method.5major factors material ori-gin and water source,topography,geological structure, soil properties and hum-an activity intensity which are most closely related to glacier debris flow ha-ve been screened out as the indicators of glacial debris flow sensitivity evalu-ation. Chosen analytic hierarchy process(AHP)to establish the hierarchical ran-king between the indicators, calculated each weight of them and finally throu-gh the overlay analysis of those weights to complete the glacial debris flowsensitivity evaluation. The study showed that: Linzhi glacier and perennial snowfield concentrateddistribution in the northern mountain, especially in GongbuJiangda, Bomi andChayu. According to two periods image data,the glacier and perennial snowfieldis retreating at the average rate of103.93km2/a,the most reduced area in Bomiand Motuo, and the largest reduced proportion in Milin and Langxian. After a-nalyzed the two extraction results combined with DEM, the proportion of glaci-er and perennial snowfield ablation can concluded that the smaller is greater th-an the larger, the lower elevation is greater than the higher elevation, the southwest slope is greater than the northeast slope. While the glacier and perennial s-nowfield accelerated retreat, the area and the number of glacial lake in Linzhiwas increasing in the past13years. In the center-north，in particular, Bomi andMotuo, the amount of glacial lake increased fast, while in Milin and Langxianmost glacial lakes disappeared. As most of the glacial lake is the result of gl-acial meltwater formed,therefore, the emergence and extinction of the glacial lakeand glacier changes are closely linked. The glaciers interacted with glacial lakewhen they connected. On the one hand, glacial meltwater leads to lake level r-ise; On the other hand, the glacial lake temperatures higher than the glacier s-urface, which accelerated the melting of glacier forefront, and intensified glacierretreat. Under the global change, the emergence and extinction of glacier, perenn-ial snowfield and glacial lake in Linzhi, was not only affected by the temperat-ure and the rainfall increased, the slope, aspect, vegetation and other topographyfactors, but also by the new tectonic movement and geological disasters. Owi-ng to the particularity of geographic condition in Linzhi, glacial debris flow disast-ers occurred frequently. So in this region four levels distribution area of debrisflow sensitivity: low, medium, high and topmost, have been demarcated by qual-itative evaluation with AHP and comprehensive multi-attribute model.The zoningresults showed that: On the whole, glacial debris flow in Linzhi has a highlysusceptibility, in Bomi, Linzhi, Gongbujiangda and Chayu county; by contrastwith the field survey data,69.56%of the known glacier debris flow point falls inthe high sensitivity zone,that means this study has certain applicability. |
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