NWT RESEARCH DATABASE

Tags: physical sciences, climate change, hydrology, permafrost thaw

Objective(s): To understand the ecology and hydrology of ecosystems with thawing permafrost.

Project Description: Understanding the ecology and hydrology of ecosystems with thawing permafrost is a major challenge. To meet this, the research team will develop new knowledge on the eco-hydrology of the major ecosystems (i.e. bogs, fens, peat plateaus) needed to develop new science-based tools to predict the future supply for the next 50 years. The specific scientific objectives are: 1) to develop fundamental knowledge of the major ecosystems and estimate the amount of water present. The watershed responses to changes in permafrost and the rate and trajectory of such changes will also be examined; 2) to develop and test a new suite of hydrological predictive tools for simulating the responses of ecosystems to permafrost thaw and the rate and pattern of ecosystem change; and, 3) to apply the new models to predict how ecosystems will respond to permafrost thaw over the next half-century. The ultimate goal of this project is to predict the stream flow regime over the next 50 years, including the total annual flow, peak flow timing and volume, baseflow amount, and frequency of high flow and low flow events. The basic frame work is similar to the standard approach used in non-permafrost regions of Canada, where a large-scale, distributed hydrological model is calibrated and validated under the present and historical conditions and subsequently used with a model of future climate. The unique challenge in the study region is that the rapid thawing of permafrost can potentially cause a major change in the hydrological characteristics of river basins. So, the conditions within each grid cell of the hydrological model need to be updated over the course of the 50-year simulation, which requires the prediction of permafrost thawing and the subsequent response of landscape (e.g. forested areas turning into wetlands). For example, a typical grid size of large-scale hydrological model may be 1 km by 1 km. For a 200 square km river basin, the model has 200 grid cells, each contain patches of permafrost (forest) and non-permafrost (wetlands). As the permafrost thaws, the shape and connectivity of the wetlands changes at a time scale of years to a decade, which is well documented in the Scotty Creek Basin. To implement these processes in a grid-based hydrological model, the team will set up several Northern Ecosystem Soil Temperature (NEST) models within each grid cell. NEST is a one-dimensional energy and water transfer model specifically designed to simulate the evolution of permafrost under different land covers. Multiple NEST models will represent different landcover types within the grid cell (e.g. bog, fen, peat plateau), and a new algorithm will be developed to simulate the lateral exchange of water and energy among the NEST models. NEST models will be embedded within a hydrological model, which provides the hydrological boundary condition for NEST, while NEST provides the information on permafrost and land cover distribution to the hydrological model. This coupling of NEST with the Raven hydrological model represents the cutting edge of scientific efforts. The coupled model development will be conducted using the data from Scotty Creek Basin. Once the model is complete, it will be tested for the Scotty Creek Basin (150 km2) and the adjacent Jean-Marie Creek Basin (2,000 km2), where long term climate and stream flow data, as well as spatial information (e.g. distribution of permafrost) are available from the analysis of archived aerial photographs and satellite images. The research team will have access to regional climate simulation data generated by Environment Canada through existing research partnerships, which will be used to drive the coupled model for future climate scenarios. Several community engagement initiatives began over the last year. Some of these were single events (e.g. guest speakers), others (e.g. field courses) are intended to continue in future years. The research team will continue to liaise with the Liddli Kue and Jean-Marie First Nations. Annual reports to the Aurora Research Institute, and publications will be sent to the communities each year. The Principal Investigator will also visit as many of the band offices and government agencies when in the Fort Simpson region. Dissemination and outreach is enhanced through the 10-year (2010- 2020) Partnership Agreement between Wilfrid Laurier University and the Government of the Northwest Territories. Recently the Partnership appointed a community Liaison to facilitate two-way communication with communities. The fieldwork for this study will be conducted from March 29, 2018 to September 3, 2018.