Inventorying slope movements in an Alpine environment using DInSAR

Differential SAR Interferometry (DInSAR) is a technique that can be used to detect and characterize slope movements. It is investigated here as a tool for establishing a detailed overview of complex slope movements at a regional scale in an Alpine context. DInSAR signals can be used to understand slope movements in mountainous areas located above the tree line, excluding glaciated areas. A systematic procedure based on accurate interpretations of interferometric signals from a large DInSAR dataset can be used to locate and estimate the displacement rate of moving zones. The methodology was successfully applied in the Western Swiss Alps, where about 1500 moving objects were detected above the tree line using a large dataset of ERS and JERS interferograms dating from the 1990s. The DInSAR-detected movements had a displacement rate ranging from a few centimeters to several meters per year and were attributed to various types of mass wasting phenomena (rock glaciers, landslides,etc.). Inventories are currently updated and upgraded.

 

Collaborators: Chloé Barboux, Reynald Delaloye

Contact: chloe.barboux[at]unifr.ch

Duration: 2007 - present

Study area: Valais (western Swiss Alps), Swiss Alps, Brookes Range (Alaska)

 

  • Illustrations

    Saas Valley (Western Swiss Alps) (a) Topographic profile, (b) Orthoimage. Interferograms of the area using ERS (c)–(g) and TSX (h)–(j) data where layover and shadowing are masked (transparent).

     

     

    Procedure for the proposed inventory of slope movements in Alpine periglacial environments using DInSAR data. The analysis is performed in GIS software.

     

     

    Detection of the Tsarmine rock glacier using ERS data. A large set of valid combinations of interferograms with different time intervals is required to increase the relevance of detected polygons. DGPS are used only to validate the order of velocity rate detected by DInSAR interpretation. (a) A small red signal could be detected on the 1?day interferogram. (b) Using a 3?day time interval, a signal could again be seen on the frontal part and around the whole landform. (c) The frontal part is now well detected on the 6?day interferogram whereas a signal appears around the rock glacier. (d) The frontal part becomes decorrelated on the 9?day interferogram. (e) The entire rock glacier is decorrelated on the 2?month interferogram. (a) Two DInSAR polygons have been drawn and classified in terms of the deformation rate as moving in the order of cm/day in red and of dm/month in orange. The outline of the landform and measured DGPS points from summer 2011 are indicated.

     

     

    Area investigated by systematic mass wasting inventories based on DInSAR data. Stars represent study sites where DGPS measurements have been performed since 2006 and are significant sources of validation. Red outlines correspond to 42 DInSAR polygons detected on daily interferograms related to solifluction slopes, landslides, push?moraines as well as rock glaciers. The orographic side of the Arolla Valley detailed in Figure?9 is localized.

     

     

     

    Orthoimages of (a) the debris?covered glacier of La Tsessette, (c) the push?moraine of Ecoulaies, and (g) the landslide of Perroc and their respective DInSAR signal on a 1?day interferogram (b) or on monthly interferograms (d) and (f). As debris?covered glaciers are not included in the inventory, no polygon is drawn in (a) and (b). DInSAR polygons were determined using a larger series of interferograms than the ones illustrated here (d) and (f). Besides all the DInSAR polygons drawn in c to f, the monthly interferograms allow only the detection of DInSAR polygons with dm/month (signal decorrelated) and cm/month ((partly)?fringe pattern).

     

     

     

    Moving landforms are often juxtaposed, when not superimposed and compose a ‘complex slope systems’, as illustrated by the orographic right side of the Arolla Valley, where moving features, including push?moraines, rock glaciers, landslides and saggings, are coalescent. (a) DInSAR detected moving zones, (b) Related landforms. The investigated area is limited due to layover, shadow and vegetation (transparent belt).

  • Collaboration

    University of Lausanne, Institute of Earth Surface Dynamics (C. Lambiel)
    Service des forêts, des cours d'eau et du paysage du Canton du Valais

  • Publications
    • Barboux, C., Strozzi, T., Delaloye, R., Wegmüller, U. and Collet, C. (2015). Mapping slope movements in Alpine environments using TerraSAR- interferometric methods. ISPRS Journal of Photogrammetry and Remote Sensing, Vol 109, Nov. 2015, p. 178-192. DOI: 10.1016/j.isprsjprs.2015.09.010
    • Barboux, C., (2014). Detection, mapping and monitoring of slope movements in the Alpine environment using DInSAR. PhD thesis, Fac. Sciences, Univ. Fribourg(pdf)
    • Barboux, C., Delaloye R. and Lambiel, C. (2014). Inventorying slope movements in an Alpine environment using DInSAR. Earth Surface Processes and Landforms, 39/15, p2087-2099. DOI: 10.1002/esp.3603
    • Rick, B., Delaloye, R., Barboux, C. and Strozzi, T. (2015). Detection and inventorying of slope movements in the Brooks Range, Alaska using DInSAR: a test study. GeoQuébec 2015, 8 p. (unpublished(pdf)
    • Barboux, C., Delaloye, R., Lambiel, C., Strozzi, T., Collet, C. and Raetzo, H. (2013). Surveying the activity of permafrost landforms in the Valais Alps with InSAR. In: Graf, C. (ed.) Mattertal – ein Tal in Bewegung. Publikation zur Jahrestagung der Schweizerischen Geomorphologischen Gesellschaft 29. Juni – 1. Juli 2011, St. Niklaus. Birmensdorf, Eidg. Forschungsanstalt WSL. 7–19. (pdf)

    • Barboux C., Delaloye R., Lambiel, C., Strozzi, T., Raezzo, H. and Collet C. (2013). Semi-automated detection of terrain activity in the Swiss Alpine periglacial environment from DInSAR scenes. Living Planet Symposium. Edinburgh (Scotland).

    • Barboux C., Delaloye R., Strozzi T., Lambiel C. and Collet C. (2013). TSX DInSAR data for detecting and monitoring slope motion phenomena in an Alpine periglacial environment at different resolution scales (Western Swiss Alps, Switzerland). TerraSAR-X Science Team Meeting, 10 - 12 June 2013, DLR Oberpfaffenhofen.

    • Barboux C., Delaloye R., Strozzi T., Lambiel C., Collet C. and Raetzo H. (2012). Monitoring active rock glaciers in the Western Swiss Alps: Challenges of Differential SAR Interferometry and solution to estimate annual and seasonal displacement rates. Proceeding of IGARSS 2012, 22 - 27 July 2012.
    • Barboux C., Delaloye R., Strozzi T., Collet C. and Raetzo H. (2011). TSX InSAR assessment for slope instabilities monitoring in alpine periglacial environment (Western Swiss Alps, Switzerland). Proceedings of the FRINGE 2011 workshop, 19-23 September (ESA SP-697, January 2012).
    • Mari, S., Delaloye, R., Scapozza, C. and Strozzi, T. (2011). Inventario dei movimenti di terreno per analisi dei segnali InSAR nelle Alpi meridionali svizzere (periodo 1994-2007). In Lambiel C., Reynard E. & Scapozza C. (eds.). La géomorphologie alpine: entre patrimoine et contrainte. Actes du colloque de la Société Suisse de Géomorphologie, 3-5 septembre 2009, Olivone. Lausanne: Université, Institut de géographie, Géovisions 36: 145-159. (pdf)
    • Delaloye, R., Strozzi, T., Lambiel, C., Barboux, C., Mari, S., Stocker, A., Techel, F. and Raetzo, H. (2010). The contribution of InSAR data to the early detection of potentially hazardous active rock glaciers in mountain areas. Proceedings ESA Living Planet Symposium 2010, Bergen, Norway (ESA SP-686). (pdf)
    • Lambiel, C., Delaloye, R., Strozzi, T., Lugon & R., Raetzo, H. (2008). ERS InSAR for detecting the rock glacier activity. Proceedings of the Ninth International Conference on Permafrost, July 2008, Fairbanks, Alaska, 1, 1019-1024. (pdf)
    • Delaloye, R., Lambiel, C., Lugon, R., Raetzo, H., Strozzi, T. (2007). ERS InSAR for detecting slope movement in a periglacial mountain environment (western Valais Alps, Switzerland). Proceedings HMRSC-IX, Graz, 14-15 Sept. 2006, Grazer Schriften der Geographie und Raumforschung 43, 113-120. (pdf)

    • Delaloye, R., Lambiel, C., Lugon, R., Raetzo, H., Strozzi, T. (2007). Typical ERS InSAR signature of slope movements in a periglacial mountain environment (Swiss Alps). Proc. ‘Envisat Symposium 2007’, Montreux, Switzerland 23–27 April 2007 (ESA SP-636, July 2007), 3P7. (pdf)