Enhancing Landslide Risk Management Through a Cost-Effective dGNSS Technology and a Method to Estimate Stability of Shore Landslides in Response to Climate Change
Creators: Berru Garcia, Ingrid Arantxa
Publisher: name: University of Alberta Library
Year: 2024

<p>Climate change is having an impact on Canada, resulting in variations in temperature, precipitation, and evaporation, among other aspects. These changes could be significant in Alberta since agriculture is a major factor in the social-economic development of the province. For example, the region&#39;s farming districts are requiring additional water for irrigation, causing a major reliance on reservoirs that in result decreases more rapidly the water levels. This reduction, known as a drawdown, has the potential to exacerbate existing landslides or trigger new landslides in the region. The geology of the region contributes to this possibility since the bedrock frequently contains layers of bentonite and coal seams, both of which have lower shear strengths and can reduce the strength to a residual strength in any disturbance, such as an increase in groundwater levels or the loss of support at toe of a slope. This could worsen in the future as the effects of climate change seem to be intensifying. Thus, improving landslide risk management techniques is necessary to identify and monitor the possible landslides, assess their failure.<br>
The thesis introduces a low-cost dGNSS technology and methodology as practical and cost-effective tools for improving landslide risk assessment and management in response to climate change effects, even under conditions of limited resources and multiple potential scenarios. Their reliability, efficiency and applicability to different landslide cases were evaluated in the Chin Coulee landslide in southern Alberta. This slow-moving landslide has disrupted a roadway since 1970 and has shown greater displacements when irrigation water demand increases.<br>
The dGNSS technology described and adopted in this study is referred to as SparkFun units designed for surveying, capable of achieving millimeter accuracy necessary for landslide monitoring when additional components are assembled to the units. Additionally, these units offer high-frequency data collection (Every minute), independence from internet services for data management, and have an approximate capital cost of USD$2000 per unit. They were customized for landslide monitoring purposes, tested and deployed for 6 months to record horizontal and vertical displacements. The monitoring data showed that the SparkFun system met its manufacturer accuracy specifications (14 mm horizontal and 10 mm vertical). The system error was within acceptable limits to monitor the landslides displacements, and the results were compared with another, commercially available, dGNSS landslide monitoring technology installed in the landslide area. The magnitude of displacement observed with the SparkFun system was lower than that of the other technology, primarily due to the monitoring period. However, both technologies exhibited similar displacement trends, aligning accurately in the vertical direction. This allows the conclusion that the SparkFun system appears to be a viable monitoring technique, enabling the management of a larger number of monitoring points in current and future landslide areas at a lower cost. <br>
Furthermore, a practical methodology was introduced to assess landslide stability in the Canadian Plains under current and future drawdown scenarios, serving as a simple tool for various entities responsible for landslide management. The methodology identifies materials that govern the stability and the pore water pressure of the landslide. Moreover, it estimates and defines the reservoir water fluctuations, drawdown rates, hydraulic and restraint boundaries conditions. This methodology demonstrated good agreement between the estimated material shear strength and permeabilities with prior studies in the landslide area and literature review. The calculated slip surface was consistent with the one proposed in prior investigations. Scenarios of future stability were informed by current trends in drawdown trends and analyzed, resulting in a 5% drop in stability compared to current conditions under the 2050-year scenario, and the landslide stability was reduced by 11% when considering a critical scenario. These results demonstrated the practicability and effectiveness of this methodology to analysis the landslide stability.</p>