雪崩是冰湖风险性评估的因子之一,借鉴欧美发展起来的雪崩模型,在冰湖溃决洪水频发的喜马拉雅山地区开展雪崩对冰湖风险性评估研究具有重要意义。基于ICIMOD IKONOS DEM和Landsat-TM数据,利用GIS方法提取了研究区雪崩形成的海拔、平面曲率、坡度和地表覆盖类型等估算因子,根据Av=(Al+Fy)×S×Rg模型估算了研究区潜在雪崩形成区域,并应用GIS方法和α-β模型估算了雪崩的传播路径。结果表明:潜在雪崩不易形成的“低”值多分布在谷底及地表覆盖类型为密林的山坡上,而“高”、“较高”值多分布在坡度为30°～50°、地表类型以裸岩或草地为主的山坡和冰川上,这些分布符合雪崩形成的客观实际;分析判断发现研究区内“高”值区域,也就是潜在雪崩形成区共有98处,其中有10处能够进入冰湖,对这些冰湖的稳定性造成风险,这意味着在分析研究区所有冰湖的溃决风险性时,只有受到潜在雪崩影响的9个冰湖需要考虑雪崩因素,其余冰湖在冰湖溃决诱因筛选中无需考虑雪崩因子。
Snow avalanche is one of the factors of assessing glacial lake risk,and it is necessary to research the risk assessment of glacial lakes by using snow avalanche models developed by Europe and America for the Himalayas where flood caused by glacial lake outburst occurs frequently. In this paper,based on ICIMOD IKONOS DEM and Landsat-TM data,the factors attributed to avalanche formation,such as the altitude,plan curvature,slope and land cover,were extracted by using the GIS means,and then the PATAs (Potential Avalanche Trigger Areas) in the study area were assessed,according to Av=(Al+Fy)×S×Rg model. In addition,the snow avalanche run-out distance was estimated by using GIS methods and α-β model. According to the estimated results,the "low" values were mainly distributed over the valley floor and slope with dense forest,where the generation probability of potential snow avalanche was very low,while the“high”and“relatively high”values were mainly distributed over the glaciers or hillsides with slope of 30°-50°,full of rock or grass,and probability of generating potential snow avalanche. The results also showed that there were 98 PATAS in the study area,ten of them could spread into the glacial lakes,and the stability risk of these glacial lakes was resulted in. On which potential snow avalanche should be considered as one of the factors inducing the outburst of only 9 glacial lakes in assessing the glacial lake risk in the study area.
〔1〕 Richardson S D,Reynolds J M.An overview of glacial hazards in the Himalayas〔J〕.Quaternary International,2000,65/66:31-47.
〔2〕 Popov N.Glacial debris-flows mitigation in Kazakstan:Assessment,prediction and control〔C〕//Cheng Chenlun.Debris-flow Hazards Mitigation:Mechanics,Prediction,and Assessment.San Francisco:Hyatt Regency San Francisco,1977:113-122.
〔3〕 Clague J J,Evans S G.A review of catastrophic drainage of moraine-dammed lakes in British Columbia〔J〕.Quaternary Science Reviews,2000,19:17-18.
〔4〕 McKillop R J,Clague J J.A procedure for making objective preliminary assessments of outburst flood hazard from moraine-dammed lakes in southwestern British Columbia〔J〕.Natural Hazards,2007,41:131-157.
〔5〕 沈永平.冰雪灾害〔M〕.北京:气象出版社,2009 .〔Shen Yongping.Disaster from Snow and Ice〔M〕.Beijing:Meterological Press,2009.〕
〔6〕 Cenderelli A D,Wohln E E.Peak discharge estimates of glacial-lake outburst floods and “normal” climatic floods in the Mount Everest region,Nepal〔J〕.Geomorphology ,2011,40:57-90.
〔7〕 Yamada T,Sharma C K.Glacier lakes and outburst floods in the Nepal Himalaya〔J〕.Snow and Glacier Hydrology,1993,218:319-330.
〔8〕 Yamada T.Glacier Lake and Outburst Floods in the Nepal Himalaya〔M〕.Tokyo:Japanese Society for Snow and Ice,1998:11-12.
〔9〕 Hreko J.Avalanche hazard of the high mountain landscape in Tatras territory (in Slovak)〔J〕.Folia Geographica 2,1998,2:348-352.
〔10〕Barka I.Identification of snow avalanche trigger areas and avalanche paths by the GIS〔J〕.Geomorphologia Slovaca,2003,3(2):60-63.
〔11〕Biskupi M,Barka I.Spatial modeling of snow avalanche run-outs using GIS〔J〕.Ostrava,2010,1:24-27.
〔12〕McClung D M,Mears A I.Extreme value prediction of snow avalanche runout〔J〕.Cold Regions Science and Technology,1991,19:163-175.
〔13〕Barbolini M,Pagliardi M,Ferro F,et al.Avalanche hazard mapping over large undocumented areas〔J〕.Nat Hazards,2011,56(2):451-464.
〔14〕McClung D,Schaerer P.The Avalanche Handbook〔M〕.Seattle:The Mountaineers Books,1993:98-101.
〔15〕Christophe A.Snow avalanche〔DB/OL〕.http://lhe.epfl.ch/pdf/snow-avalanche.pdf,2002/2015.
〔16〕McClung D,Schaerer P.The Avalanche Handbook 3〔M〕.Seattle:The Mountaineers Books,2006.
〔17〕McClung D M.Characteristics of terrain snow supply and forest cover for avalanche initiation caused by logging〔J〕.Annals of Glaciology,2001,32:223-229.
