长江黄河源区冰川变化及其对河川径流的影响

以位于青藏高原长江源头的各拉丹冬地区和黄河源区的阿尼玛卿山地区冰川为例,利用两期遥感影像资料(长江源为1969年和2000年,黄河源为1966年和2000年),在地理信息系统技术的支持下分析研究区典型冰川作用区小冰期(LIA)、1969年(1966年)和2000年的冰川范围变化、冰川进退情况,在此基础上,运用由点到面的研究方法,外推整个长江和黄河源区近几十年来的冰川变化情况,并以沱沱河流域为例,分析了冰川变化对河川径流的影响。结果表明,长江源各拉丹冬地区1969～2000年冰川总面积减少了1.7%,而黄河源阿尼玛卿山地区冰川面积减少是长江源区的10倍,同期,长江源区冰川末端的最大退缩速率为每年41.5m,而黄河源区每年为57.4m,与黄河源区相比,长江源区冰川退缩速度不是太大,基本上处于稳定状态,且有前进冰川存在。20世纪60年代以来,江河源区冰川虽呈长期退缩的总趋势,但也出现过明显的前进,长江源区在1969年～1995年,黄河源区在1966年至1981年,大多数冰川处于前进状态或稳定。长江源区冰川转入退缩阶段的时间要比黄河源区晚约10a左右。冰川退缩使长江源区和黄河源区年均各自损失冰川水资源约0.7×108m³。由于长江源区冰川变化幅度小,虽冰川退缩使冰川融水径流量有所增加,但对径流的影响程度相对较小。

Glacier change and its effect on surface runoff in the source regions of the Yangtze and Yellow rivers

Glacier is an important component of eco-environment in the source regions of the Yangtze and Yellow rivers.The effects of glacier change on eco-environment has attracted re-searcher's attentions for a long time past in the source regions.GIS provides an efficient tool to analyze the status and change of glaciers.In the paper,the Geladandong area in the source region of the Yangtze River and A'nyêmaqên Mountains in the source region of the Yellow River are selected as the test areas.Based on RS data in the two periods-one in1969and the other in2000in Geladan dong area of the source region of the Yangtze River,one in1966and the other in2000in A'nyêmaqên Mountains of the source region of the Yellow River,glacier variations during the Little Ice Age(LIA)maximum,in1969(1966)and2000are analyzed by means of aerial photos,satellite images,topographic maps and the derived digital elevation models (DEM).Glacier changes in the whole source regions of the Yangtze and Yellow rivers are inferred from study of the above two test areas.Tuotuohe basin is selected as typical area.The impacts of glacier variations on surface runoff are analyzed in Tuotuohe basin in the paper.The results indi-cate that the glacier area had decreased by about 1.7%from1969to2000in Geladandong area of the source region of the Yangtze River,while about 17%from1966to2000in A'nyêmaqên Mountains of the source region of the Yellow River,and that the largest retreat rate of glacier terminus is41.5m per year in the Geladandong area,while57.4m per year in A'nyêmaqên Mountains.Compared with glaciers in the source region of the Yellow River,withdrawal rate of glaciers is smaller and glaciers seem almost steady in the source region of the Yangtze River.Glaciers advance markedly from1969to1995in the source region of the Yangtze River and from1966to1981in the source region of the Yellow River.At this period the majority of glaciers is in advance or stable state.The changing time from glacier advance into retreat in the source region of the Yangtze River is about 10years later than that in the source region of the Yellow river.Glacier retreat results in about 7million cubic meters losses of glacier causes water resources every year in the source regions of the Yangtze and Yellow rivers,respectively.Although retreat of glaciers causes increase in glacier melt water runoff,the effect of glacier retreat on sur -face runoff is relatively small because of small ampli tude of glacier change.