4-decadal Glacier Lake Inventory for Arunachal Pradesh, India

The study is towards the preparation of a glacial lake inventory for Arunachal Pradesh and a critical analysis of 40 years temporal change in the lake area along with the long-term change of temperature and precipitation, the characteristics of glacial lake outburst probability and the hazard assessment and the relationship between glacial lakes and climate change. Results showed that there was an obvious increase in the temperature of the basin since 1970. Specifically, in the mountainous area, the significantly increasing temperature in the summer and autumn seasons accelerated the melting rate of glaciers and the formation of a glacial lake. With the use of LANDSAT (1, 2, 4, 5, 7, 8) datasets from 1973-2013, Google earth imagery of various data and Toposheets from SOI the glacial lake inventory was created. In Arunachal Pradesh, the number of glacier lakes increased by 142 between 1970 and 2013. The rate of area change in glacial lakes over the years varies as high as 1000% in the time span of 1970-2013, and almost 370% in the time span of 1980-2013 and 2001-2013. Decade wise analysis shows that the highest number of lakes and higher amount of area change over 40 years is found in the zone 4000-4500 m. Based on remote sensing techniques only with topographic analysis viz. elevation, slope, aspect, the curvature of lakes derived from ASTER DEM data, 33 lakes were considered critical and 28 lakes potentially critical in Arunachal Pradesh after the Hazard assessment of the glacial lake inventory. The evaluation and classification of the outburst probabilities of glacial lakes by remote sensing are challenging and different approaches have been presented in many literatures. The approach present in this study is efficient for analyzing a large number of lakes that need further quantitative assessment. In addition to the rise in temperature and extreme climatic conditions observed since 2000, the glacier lakes associated with the glacier melting are increasing in number and size and to some extent, the potential of glacial lake outburst floods increases. Thereby, persistent attention should be paid to the influences of climatic change in the region and future disaster preparedness by authorities and locals.本研究旨在编制阿鲁纳恰尔邦的冰湖（glacial lake）名录，并针对40年来冰湖面积的时间变化、气温与降水的长期演变、冰湖溃决概率特征、灾害评估以及冰湖与气候变化之间的关联开展批判性分析。研究结果表明，自1970年以来该流域气温呈显著上升趋势。具体而言，山区夏季与秋季的气温显著升高，加快了冰川消融速率，进而促进了冰湖的形成。本研究借助1973-2013年的LANDSAT（1、2、4、5、7、8）数据集、多源谷歌地球（Google Earth）影像以及SOI（印度测量局，Survey of India）的地形图图件，完成了冰湖名录的构建。在阿鲁纳恰尔邦范围内，1970至2013年间冰湖数量增加了142个。1970-2013年期间，冰湖面积变化率最高可达1000%；1980-2013年以及2001-2013年期间，面积变化率则接近370%。十年尺度的分析结果显示，在40年的研究周期内，冰湖数量最多、面积变化幅度最大的区域集中在海拔4000-4500米的区间。基于遥感技术，结合ASTER数字高程模型（ASTER DEM）数据提取的湖泊地形参数（包括海拔、坡度、坡向与曲率）开展地形分析，本研究完成冰湖名录的灾害评估后，将阿鲁纳恰尔邦内的33个冰湖判定为高危冰湖，28个冰湖判定为潜在高危冰湖。利用遥感技术开展冰湖溃决概率的评估与分类具有较高挑战性，现有诸多文献已提出了多种不同的研究方法。本研究采用的方法可高效处理需开展进一步定量评估的大规模冰湖样本。除2000年以来观测到的气温上升与极端气候事件外，与冰川消融相关的冰湖在数量与规模上均呈增长趋势，冰湖溃决洪水（glacial lake outburst flood）的发生潜力在一定程度上有所提升。因此，该区域的气候变化影响以及未来防灾减灾工作应持续受到当地政府与民众的高度重视。