NWT RESEARCH DATABASE

Tags: physical sciences, active layer, permafrost, hydrology, ground thaw

Objective(s): To examine the energy balance of the seasonally thawed layer (i.e. active layer) that overlies the permafrost in the wetland-dominated region of the lower Liard River valley.

Project Description: The objective of this project will examine the energy balance of the seasonally thawed layer (i.e. active layer) that overlies the permafrost in the wetland-dominated region of the lower Liard River valley. Specifically, the following questions will be addressed: 1) What are the major factors (e.g. soil moisture, tree canopy density) controlling the flow of energy into and from the active layer? 2) How do these factors vary over space? 3) What values for these factors are needed to maintain the permafrost? 4) Do ground-based measurements indicate that permafrost melt is occurring? 5) If permafrost melt is suggested by ground measurements, is the same suggested by satellite/aerial images of the region, and if so to what extent? In order to address the objectives stated above, the following measurements will be made at Scotty Creek: 1) Heat flow into the ground over the thaw season at a peat plateau (i.e. a site with permafrost and trees) and at an adjacent bog and linear disturbance (i.e. sites with neither permafrost nor trees) for the period of soil thawing. This will be measured with a graduated steel rod along transects. Measurements will be repeated weekly. 2) Use automatic sensors to measure the balance of heat flow into and out of the ground over the entire year at several points on a peat plateau and at an adjacent bog and linear disturbance. These small portable sensors will be connected to a data logger so that they can be left at the study site over the winter period. 3) Measure the spatial variability of energy flow into the ground on a peat plateau. This will be done using the same instruments identified above, but the measurements will be made at a sampling grid set-up for intensive measurement of multiple variables. This grid will be 50 m x 50 m and the measurement points will be 10 m apart (i.e. 25 measurement points). At each point, the following measurements will be made weekly: depth of soil thaw, soil moisture content and tree canopy density above the point. 4) Review ground-based measurement records (e.g. soil temperature, soil thaw transects and active layer energy balance) from recent years for evidence of permafrost melt. 5) Review recent aerial images, including the 1947-2008 aerial photograph archive of the study region for evidence of landscape change resulting from permafrost melt. Any detectable change will be measured using image analysis software. The researchers are hoping to meet with community groups that might be interested in the information they are generating. Annual reports to the Aurora Research Institute and publications will be sent to the communities each year. Dr. Quinton also visits as many of the band offices and government agencies when he is in the Fort Simpson region. The fieldwork for this study will be conducted from April 01 to September 15, 2010, within the Scotty Creek drainage area, approximately 62 km SSW of Fort Simpson, 15 km SSW of Checkpoint, and 1.1 km north of Goose Lake.