Debris volume estimation and monitoring of Phuktal river landslide-dammed lake in the Zanskar Himalayas, India using Cartosat-2 images

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• 作者：Tapas R. Martha ; P. Shashivardhan Reddy ; C. M. Bhatt ; K. Babu Govindha Raj…
• 关键词：Rockslide ; DEM ; VHR satellite data ; LLOF ; Natural dam ; Tsarap
• 刊名：Landslides
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：14
• 期：1
• 页码：373-383
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Natural Hazards; Geography, general; Agriculture; Civil Engineering;
• 出版者：Springer Berlin Heidelberg
• ISSN：1612-5118
• 卷排序：14

文摘

On 31 December 2014, a large landslide in the Zanskar Himalayas, India created a 69-m high natural dam on the Phuktal river resulting in formation of a 17.2 km long impounded lake with 150 m width near the blockade. In this study, very high-resolution Cartosat-2 (1 m) multi-temporal images were used for geomorphic investigation, debris volume estimation and monitoring of the Phuktal river landslide-dammed lake. Geomorphic analysis carried out using Cartosat-2 images shows that the Phuktal river landslide occurred in two phases in quick succession. Rapid estimation of the volume of landslide debris was done indirectly by surface volume method using a reconstructed geometry of the debris area mapped (90,422 m2) from the Cartosat-2 image acquired on 20 January 2015. Subsequently, direct volume by fill volume method was estimated from a post-landslide digital elevation model (DEM) created by photogrammetric techniques with availability of more Cartosat-2 images (25 January 2015 and 21 February 2015) from adjacent orbits. In both the methods, a pre-existing 10-m DEM created from Cartosat-1 (2.5 m) stereoscopic images of 17 October 2010 was used as baseline elevation data. The debris volumes estimated by indirect and direct methods are 2,624,873 and 2,433,173 m3 respectively. The difference in volume is attributed to reduction of debris surface area to 78,202 m2 due to the spread of water onto the landslide dam on 21 February 2015. Indirect volume estimated by constraining the debris surface area to 21 February 2015 was found to be 2,530,125 m3, which is a deviation of 4 % with respect to volume estimated by direct method. This indicates that landslide volume can be estimated fairly accurately in gorges in the absence of a post-landslide DEM. Results of the study were useful for supporting disaster management activities until landslide dam breached on 07 May 2015.