Kharuk Viacheslav I, Shushpanov Alexandr S, Im Sergei T, Ranson Kenneth J
Sukachev Forest Institute, Krasnoyarsk, 660036, Russia.
Siberian Federal University, Krasnoyarsk, 660041, Russia.
Environ Res Lett. 2016 Apr;11(4). doi: 10.1088/1748-9326/11/4/045004. Epub 2016 Apr 13.
Climate impact on landslide occurrence and spatial patterns were analyzed within the larch-dominant communities associated with continuous permafrost areas of Central Siberia. We used high resolution satellite imagery (i.e. QuickBird, WorldView) to identify landslide scars over an area of 62000 km. Landslide occurrence was analyzed with respect to climate variables (air temperature, precipitation, drought index SPEI), and GRACE satellite derived equivalent of water thickness anomalies (EWTA). Landslides were found only on southward facing slopes, and the occurrence of landslides increased exponentially with increasing slope steepness. Lengths of landslides correlated positively with slope steepness. The observed upper elevation limit of landslides tended to coincide with the tree line. Observations revealed landslides occurrence was also found to be strongly correlated with August precipitation (r = 0.81) and drought index (r = 0.7), with June-July-August soil water anomalies (i.e., EWTA, r = 0.68-0.7), and number of thawing days (i.e., a number of days with t > 0°C; r = 0.67). A significant increase in the variance of soil water anomalies was observed, indicating that occurrence of landslides may increase even with a stable mean precipitation level. The key-findings of this study are (1) landslides occurrence increased within the permafrost zone of Central Siberia in the beginning of the 21st century; (2) the main cause of increased landslides occurrence are extremes in precipitation and soil water anomalies; and (3) landslides occurrence are strongly dependent on relief features such as southward facing steep slopes.
分析了气候对西伯利亚中部连续多年冻土区落叶松为主群落中滑坡发生情况及空间格局的影响。我们使用高分辨率卫星图像（即快鸟卫星、世界视图卫星）识别了面积达62000平方千米区域内的滑坡痕迹。针对气候变量（气温、降水量、干旱指数SPEI）以及GRACE卫星反演的等效水厚度异常（EWTA），分析了滑坡的发生情况。仅在朝南的斜坡上发现了滑坡，且滑坡的发生随着坡度的增加呈指数增长。滑坡的长度与坡度呈正相关。观测到的滑坡海拔上限往往与树木线重合。观测结果还显示，滑坡的发生与8月降水量（r = 0.81）、干旱指数（r = 0.7）、6 - 7 - 8月土壤水分异常（即EWTA，r = 0.68 - 0.7）以及解冻天数（即气温t > 0°C的天数；r = 0.67）密切相关。观测到土壤水分异常的方差显著增加，这表明即使平均降水量水平稳定，滑坡的发生仍可能增加。本研究的主要发现为：（1）21世纪初，西伯利亚中部多年冻土区内滑坡发生次数增加；（2）滑坡发生次数增加的主要原因是降水极端情况和土壤水分异常；（3）滑坡的发生强烈依赖于诸如朝南陡坡等地形特征。
