NWT RESEARCH DATABASE

Tags: physical sciences, hydrology, prediction models, water quantity, ecology, permafrost thaw, ecosystem, ecosystem

Objective(s): To develop fundamental knowledge of the major ecosystems and estimate the amount of water present; to determine watershed responses to change in permafrost regime and the rate and trajectory of such changes; to develop and test a new suite of eco-hydrological predictive tools for simulating the responses of ecosystems to permafrost thaw; and to apply the new integrated eco-hydrological models to predict terrestrial and aquatic ecosystem responses to permafrost thaw extending to the year 2062.

Project Description: Understanding the integrated eco-hydrological behaviour of ecosystems in the context of thawing permafrost is a major challenge. To meet this, the research team will provide rigorous estimates of the present surface and near-surface water supplies and their inter-annual variability assuming a condition of no permafrost thaw. The research team will also develop critical 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 of water in the HRB for the next 50 years. The specific scientific objectives are to: - develop fundamental knowledge of the major ecosystems and estimate the amount of water present. The watershed responses to changes in permafrost regime and the rate and trajectory of such changes will also be examined; - develop and test a new suite of eco-hydrological predictive tools for simulating the responses of ecosystems to permafrost thaw; and - apply the new integrated eco-hydrological models to predict terrestrial and aquatic ecosystem responses to permafrost thaw extending to the year 2062. The research team will examine permafrost, ecology, hydrology and their interactions. The present condition of each of these Earth system components is determined by extrinsic factors including prevailing climate, disturbance and geological setting. Further, these factors display complex feedbacks and interactions that influence ecosystem function and services. To understand these complexities, the research team will begin by evaluating and integrating state-of-the-art models to identify the knowledge gaps, especially those that cross disciplines. This knowledge will be used to drive the field and laboratory research, with integration occurring annually and in a final culminating Report. The goal of this project is to predict the stream flow regime until the year 2062, 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. Therefore, 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 2000 km2 river basin, the model has 2000 grid cells, each of which may contain discrete patches of permafrost-supported forests coexisting with non-permafrost wetlands. As the permafrost thaws, the shape and connectivity of wetlands (i.e. water storage and transmission features) change 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 in a computationally efficient manner, the research 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 landcover distribution to the hydrological model. This coupling of NEST with a hydrological model represents the cutting edge of scientific efforts. There are a number of hydrological models that may be suitable for coupling. At the moment, the research team is evaluating a possibility of using a Canadian model called Modélisation Environmentale Communautaire - Surface Hydrology (MESH), which is based on the widely-used Canadian hydrological model WATFLOOD. 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. Guidance of the project will be sought through public consultation with community groups at Jean-Marie and Fort Simpson. The research team will continue to liaise with the Liidlii Kue and Jean-Marie First Nation. Annual reports to the Aurora Research Institute and publications will be sent to the communities each year. The principal investigator also visits 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 Laurier and the GNWT. Recently the Partnership appointed a community Liaison (Christine Wenman) to facilitate two-way communication with communities. The fieldwork for this study will be conducted from March 15, 2013 to September 15, 2013.