NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Objective(s): To integrate field observations, geochemical techniques, and historical remote sensing analysis to quantify the rates and processes by which sediment is generated from bedrock and transported downslope via hillslope and river processes under a changing climate.

Project Description: This licence has been issued for the scientific research application No. 5940. The proposal for this latest phase of the research is to integrate field observations, geochemical techniques, and historical remote sensing analysis to quantify the rates and processes by which sediment is generated from bedrock and transported downslope via hillslope and river processes under a changing climate. The major objectives are to: (1) conduct fieldwork to determine the processes by which bedrock is broken down into transportable sediment and how that sediment moves across the landscape; (2) perform laboratory analyses on samples collected in the field to quantify rates of sediment production and transport over decadal to millennial scales; (3) use remote sensing techniques, historical imagery, and Gwich’in traditional knowledge to extend our local findings to the broader region over the last several decades; and (4) use these data to calibrate sediment production and transport models so that we can predict future landscape response to warming. The alluvial fans to be studied are on Gwich’in private lands (see attached maps). Permission is requested to access and camp on/near the fans over the course of three separate field seasons (between 2022–2026), ideally with the assistance of wildlife monitors and occasional community participants from Aklavik (and/or Inuvik). In case there are issues accessing the field area, due to restrictions related to the COVID-19 pandemic, the request is to have a five-year permit (2022–2026) in case fieldwork is not possible during one of these years. Our three proposed field campaigns would span ~3–4 weeks during the summer months (either late May–June or in July–August) and would include 4–6 scientists. The plan to study two alluvial fans and their catchment areas from three or four separate camps (see attached map). The first camp location would be at the base of the Black Mountain fan along the Husky Channel, which is the same site where work took place in 2019 (67.965423°, -135.339320°). In addition, the plan is to establish a helicopter-based camp within the higher catchment of Black Mountain (67.968743°, -135.432826°). The third proposed camp location has yet to be clearly identified, but it will probably be located near the snowmobile trail that accesses Red Mountain from the Husky Channel (68.079921°, -135.383661°). If that does not look good, a higher camp may be a better option, within the upper catchment of Red Mountain by using helicopter access (68.096504°, -135.431797°). Seasonal Surveying/Monitoring A. Walk up and down the fans to make general observations about sediment grain sizes, to observe channels and if there are sediment deposits in those channels. In addition, detailed observations will be performed of the catchment headwall regions to understand the nature of the bedrock fracture patterns and their potential for the creation of landslides. B. Annual uncrewed aerial vehicle (UAV), or drone, mapping of the Black and Red Mountain fans. This will entail ~1-2-day mapping campaigns using quadcopter or fixed-wing UAVs depending on the nature of our take-off/landing options. C. Annual use of a terrestrial LiDAR scanner to make detailed topographic maps of portions of the fan and the catchment headwalls. These temporary scanners are mounted on tripods and use light to re-create 3D models of the ground surface. Much of the region has been imaged with lidar from aircraft, but ground-based LiDAR can allow us to see smaller scale features. D. At each camp, the plan is to install a temporary broadband seismometer to monitor the seismic activity occurring in the Aklavik Range. This instrument is shaped like a small suitcase with a similar-sized solar panel and will only be on-site while we are in camp. Continuous Monitoring A. Examine the fans: look for ~20–30 sites at the top of the fan, mid-fan, and at the downstream end of the fan to make detailed measurements. At these sites, dig very shallow pits (<1 meter deep) to document the presence of ice in the ground and install temperature sensors, or probes, to record the soil conditions. Install ~5–6 probes in select locations, and these probes would remain in the soil for the duration of our study. Probes are ~1–2 m long PVC pipes with data loggers and would be removed in the last field season. B. In the catchment headwall regions: install thermocouples and temperature loggers that would be placed within holes drilled into the bedrock. Small (<2-inch diameter) holes, ~50-100 cm deep, will need to be drilled into the bedrock with a gasoline-powered drill, to place sensors deep enough to examine the annual temperature fluctuations within the headwall catchments. These sensors would remain in the catchment walls for the duration of our study and be removed during the last field season. C. Installation of two weather stations: one in each of the Red and Black Mountain catchments. These weather stations are approximately 2 m tall and have small solar panels and batteries that are mounted on steel tripods. These stations can facilitate continuous daily weather data logging throughout the year. D. Installation of two stream gauges: one in each of the active channels in both the Red and Black Mountain fan systems. These stream gauges consist of small cameras mounted on steel-frame tripods that also have a battery and solar panel. Gauges to be removed at the end of the study in our final field season. Sampling A. At the same ~20–30 monitoring sites containing the soil pits (discussed above): collect small samples of soil for documenting the history of sediment accumulation and the movement of the sediment during (~1 L total/pit). B. In the bedrock catchment areas: collect cores that are drilled into the bedrock, along with ~10-20, 1–2 kg rock samples for geochemical analysis. Cores would be sampled throughout the catchment systems and would be collected with rock hammers. C. Along the fan surfaces and in the active channels: collect ~25 samples of woody or plant debris for radiocarbon dating, to precisely constrain the ages of ancient fan deposits. In addition, collection of a similar number of sediment samples will be taken, to constrain the type of sediments that are being transported within the active channels. D. Drill two sediment cores in the lakes in front of each the Black and Red Mountain fans. The fieldwork for this study will be conducted from: July 16 - August 02, 2024; August 28 - September 11, 2024