NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area, Sahtu Settlement Area

Tags: physical sciences, geology, soil, landslides, topography, ground truth survey, mapping

Project Description: The goal of this project is to compile updated baseline information/knowledge on the types, regional distribution, and controls (e.g. forests fires, climate change) of landslides. The main objectives of the field reconnaissance at landslide sites are six-fold: 1) to validate previous data collected through air photo interpretation and remote sensing techniques; 2) to carry out detailed mapping at specific landslide sites visited last year and new sites north of Inuvik; 3) to instrument landslide sites that exhibit on-going movement in order to qualify the rate of movement through remote sensing; 4) to identify main failure mechanisms and factors that contributed to failure of landslides; 5) to collect soil samples that could permit to characterize materials involved in slope failures; and 6) to determine the influence of past forest fires as triggers for landslides. Year 2 of this two-year project aims to accomplish detailed landslide mapping and data validation at specific sites. Detailed surveys using non-disruptive equipment (ground survey equipment) will be conducted at landslide sites to obtain detailed profiles, cross sections, and soil stratigraphy. Small soil samples (about 30cm³) will be collected at specific sites for subsequent laboratory testing in order to define physical/mechanical properties of materials involved in slope failure. Active layer depth will also be recorded. The detailed investigation will take place at the three priority regions, around Inuvik, Tsiigehtchic and between Norman Wells and Fort Good Hope. In the vicinity of landslide sites, vegetation conditions will be examined (more specifically, its conditions following forest fires). No vegetation samples will be taken. An important component of the research project is the application of an innovative remote sensing technique called InSAR or Interferometry-Synthetic Aperture Radar. Temporal sequences of Radarsat satellite images allow 1) mapping of large landslides, and 2) monitoring of ground displacements of active landslides that show either retrogressive movements at the headscarp or movements within the failed debris mass. The InSAR technique uses corner reflectors (light, pyramid-shape metal structure with dimensions about 1x1x1m) installed on the ground that act as permanent reference points. They also serve to monitor ground displacement when installed on slopes showing ongoing movements. Through this instrumentation, the rate of movement of slopes that may pose a serious threat to fauna and vegetation habitats, as well as topotential infrastructure, can be evaluated. The installation of these reflectors will not cause any ground disturbance. Access to landslide sites will be by helicopter, and once at the site, access to specific landslide features will be by foot to minimize disturbance. As most of the work in this project is done through air photo interpretation and space imagery analyses, fieldwork will consist mostly of mapping and validation of existing data.Research results will be disseminated through government websites (both Federal and Territorial), local seminars and exhibitions at local visitor centres or community centres, and local RRC offices. Results will also be communicated in scientific journals and papers. Copies of articles and papers will be shared with interested parties upon request. Fieldwork will be conducted from August 14-24, 2006 within landslide amphitheatres and their vicinities in three principal areas: 1) Travaillant Lake-Thunder River (67.2 130; 67.75 130; 67.49 130.99; 67.75 132; 67.37 132.01), 2) north of Inuvik (68.45 132.95; 68.32 133.86); 69 134.65; 69.16 133.73), and 3) at rockslides between Norman Wells and Fort Good Hope (65.46 127.65; 65.56 127.33). These investigation sites correspond to priority sites for landslide investigations as they include various types of landslides and various permafrost and geology conditions.