Influence of Mackenzie Delta Channel Thermal Regime on Permafrost

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: physical sciences, permafrost, prediction models, seasonal variation, thermal regime

Principal Investigator: Ensom, Timothy P (3)
Licence Number: 14517
Organization: Carleton University Department of Geography and Environmental Studies
Licenced Year(s): 2010 2009
Issued: May 08, 2009
Project Team: Timothy Ensom (Lead Researcher, Carleton University), Andrew Thoms (Field Research Assistant, Carleton University), Steven Kokelj (Northern Partner, Water Resources Division DIAND)

Objective(s): The purpose of this research is to measure the seasonal temperatures of streambeds at several sites in the Mackenzie delta and adjacent tundra uplands, and predict the implications of these temperature patterns for local permafrost conditions.

Project Description: The purpose of this research is to measure the seasonal temperatures of streambeds at several sites in the Mackenzie delta and adjacent tundra uplands, and predict the implications of these temperature patterns for local permafrost conditions. This project will seek to determine whether channel size and depth affect the annual thermal regime of the streambed, and will also use collected temperature data to test existing theories about how surface water bodies affect permafrost.

1. Site Selection

Mackenzie Delta channel sites will be selected using the following criteria:
1) Sites should present a range of different channel widths to allow comparison of stream temperature with channel size.
2) Sites should have unchanging or only slowly-changing permafrost conditions. Sites where channels are straight or only slightly curved are therefore preferred. If a channel is curved, ground temperature the cut-bank side (the outside of the curve) will be investigated.
3) Water bodies other than the channel should be more than 750 m away.

2. Field Methods

2.1 Ground Temperature
At each delta channel site, four boreholes will be drilled by water jet at distances of 5, 15, 100, and approximately 750 m from the channel. Ground temperature will be recorded by thermometers at depths of 6, 9, 12, 15, and 20 m along cables installed in the boreholes. A maximum depth of 20 m is selected because this depth usually corresponds well with average annual ground surface temperature. Following installation in mid-June 2009 and a period of several weeks for ground temperature to return to normal, temperature readings will be taken approximately every two weeks from early July through late-August 2009. Additional readings will be taken in February 2010 (mid-winter) and again in mid-May 2010.

2.2 Channel Thermal Regime
In early June 2009, sealed thermometers will be anchored to the stream or channel bed at each delta and tundra site. Anchors will be fastened to shore by special cable to permit temperature readings from shore. In August, cable from the underwater thermometers will be fed through steel pipe installed beneath the shoreline using water jet drilling. Encasements for data storage devices will be installed beyond the expected limit of channel ice and be clearly marked to ensure winter visibility. Stored temperature recordings will be downloaded during the February field visit, and again in May when the apparatus will be removed prior to channel ice breakup.

2.3 Analysis Methods
Average annual stream and channel bed temperature will be determined from measurements obtained at each site. These averages will be used to estimate the depth to permafrost beneath the channels. Ground temperature measurements will also be compared with estimates made of ground temperature using channel water temperature. The measured ground temperature will therefore help improve existing ground temperature models.

Research results will be shared with any interested community organizations’ members.

All interested parties will be provided with a report and/or copy of the researcher’s Masters thesis. He plans to communicate with community members while conducting his research, and would be pleased to make presentations of results to interested groups during subsequent visits to the region.

The fieldwork for this study will be conducted from May 11 to August 31, 2009, at channel sites in the eastern Mackenzie delta and at stream sites on adjacent tundra uplands near Inuvik, NWT. Preliminary site locations for data collection (in degrees, minutes, seconds) are as follows:
Mackenzie Delta:
MD1: 68.33 N, 133.70 W
MD2: 68.33 N, 133.83 W
MD3: 68.34 N, 133.97 W
MD4: 68.39 N, 133.98 W
MD5: 68.38 N, 134.15 W
MD6: 68.44 N, 134.24 W
MD7: 68.23 N, 134.21 W
MD8: 68.99 N, 134.21 W
MD9: 68.21 N, 134.67 W
MD10:68.46 N, 134.54 W
MD11:67.92 N, 134.36 W
MD12:67.89 N, 134.47 W
MD13:63.83 N, 134.78 W
MD14:68.61 N, 134.83 W
MD15:68.64 N, 134.76 W

Tundra Uplands:
TU1: 68.38 N, 133.69 W
TU2: 68.36 N, 133.67 W