祁连山中部素珠链峰地区冰川斑块动态分析

冰川斑块对气候变化的响应不仅表现在冰川长度和面积的变化,而且其格局在斑块数量、形状、平均欧几里德距离、连通度和最大斑块指数等指标上都发生了显著的变化.运用RS和GIS技术对祁连山东段典型地区2001-2009年间冰川斑块动态的分析表明:研究区冰川斑块面积减少了15.39%,面积<1 hm²的小斑块数量消失了50%以上,斑块形状指数在总体和分级层次上都呈减少的趋势,最大斑块的优势降低.由于小斑块消融和大斑块收缩,使斑块间平均欧几里德距离增加了16.56 m.斑块连通度具有尺度依赖性,当在阈限值<7 000 m时,2009年的冰川斑块连通度大于2001年;当阈限值>7 000 m时,趋势相反.7 000~8 000 m之间是尺度特征的转折点.从斑块动态变化来看,冰川斑块动态以消融斑块为主,消融面积为744.30 hm²,占起始面积的16.53%;新生斑块也同时发生,仅增加起始面积的1.15%.但是,消融和新生斑块发生的数量较多,分别为762和367个,冰川单个斑块面积大小与消融面积呈正相关.

Glacier Patch Dynamics in the Suzulian Peak Area of the Middle Qilian Mountains

Climate change has exerted increasing impacts on glaciers, not only on rainfall and snowfall, but also on landscape pattern. Analysis of the glacier patch dynamics, based on RS and GIS data, in the middle Qilian Mountains showed that the glacier patch area was reduced by 15.39%, small patches with an area less than 1 hm² was reduced by more than 50%, patch shape index was declined in general, and the dominance of the largest patch was reduced too from 2001 to 2009. It thus made the mean Euclidean Distance between patches increased by 16.56 m. The patch connectivity had scale dependent effect and was higher in 2009 than that in 2001 when the threshold value was set less than 7000 m; when the threshold value was set more than 7000 m, the connectivity was changed reversely. In terms of patch types, the ablation patches played an important role in glacier degradation, and the ablation area was 744.30 hm², about 16.53% of the glacier area at the beginning. Simultaneously, the generated patches were produced but increased only by 1.15% of the glacier area at the beginning. There was a positive correlation between the ablation and generated glacier patch areas in the period from 2001 to 2009.