Impact of seismic lines on the hydrology of wetlands in the discontinuous permafrost zone, southwestern Northwest Territories

• Main Author: Hamilton, Angela
• Format: Text
• Language: English
• Published: Scholars Commons @ Laurier 2020
• Subjects: Seismic line; hydrology; permafrost; wetland; Canada; linear disturbance; Environmental Indicators and Impact Assessment; Environmental Monitoring; Water Resource Management; Northwest Territories
• Online Access: https://scholars.wlu.ca/etd/2299; https://scholars.wlu.ca/context/etd/article/3419/viewcontent/MSc_Geogrpahy_Thesis__Angela_Hamilton_August_7_2020.pdf

Previous studies in the southern Northwest Territories have shown the underlying discontinuous permafrost is sensitive to disturbances such as the creation of seismic lines. Their creation has resulted in compaction topsoil and tree removal causing accelerated permafrost thaw. The loss of permafrost has caused seismic lines’ surface elevation to subside, which allows water to conjugate. This increases the soil moisture of a seismic line, which results in preferential thaw along the seismic line edges. Thaw along the edges over time has connected more previously isolated wetlands to seismic lines. This leads to more water entering, resulting in higher water levels in seismic lines, which increases the landscape runoff. More runoff means less water is being stored on the landscape causing the affected land features to change. However, the hydrological effect on adjacent connected wetlands is still unclear. The research objective of this study is to create a better understanding of wetlands that are hydrologically connected to seismic lines in efforts to create more accurate prediction models. In particular, the study focuses on the partial draining of wetlands that are connected to a seismic line established in 1985. Three wetlands with contrasting degrees of hydrological connection (open connected, narrow channel connected, and isolated) to the seismic line were monitored. The wetlands were monitored for surface elevation, water level, surface water recession, and soil moisture. There are two main findings of this study: 1) the surface elevation and water level of the connected wetlands were significantly lower than the isolated wetland 2) the plateau fringe’s soil moisture of the connected wetlands were significantly higher than the isolated wetland. From these observations, it was inferred that a higher soil moisture along the plateau fringe is likely to result in a change of the connected wetlands’ catchment. Connected wetlands provide a secondary runoff input. Because of an increased runoff, the recovery of ...