Climate change and the water towers of western Canada

Floods in the Nechako River Basin

Remote sensing of snow

References

Last Modified 2024/04/29

Research Statement

Snow and ice are ubiquitous features of the Canadian landscape. Thus the hydrometeorology of high latitude and elevation watersheds is largely controlled by processes involving snow and ice. Although our understanding of snow and ice processes has improved in recent years, there remains some fundamental issues that need to be addressed. This is an especially urgent matter as the northern high latitudes are currently experiencing an unprecedented period of climate change (Serreze et al. 2000). Thus there is a great need to quantify the role of snowcover in the existing and in the future states of the surface energy and water budgets and to better comprehend hydrometeorological processes in the North.

Our research is therefore geared towards a better understanding of northern hydrometeorological processes and their impacts on the surface energy and water budgets. To accomplish this goal, a variety of methods and tools are used, including field observations, reanalysis datasets, remote sensing data, and numerical modeling. We are interested in both small-scale (from meters to a few kilometers) and large-scale (> kilometers) hydrometeorological processes.

Below are several research topics that have been undertaken by our group. For more information on the PIEKTUK model and our previous work on blowing snow, please consult the following page. Details of our ongoing field work at the Quesnel River Research Centre (QRRC) and the Cariboo Mountains can be found at the Cariboo Alpine Mesonet website. Also listed below are the current members the NHG and funding sources.

Equity, Diversity and Inclusion (EDI) Statement and Philosophy

The Northern Hydrometeorology Group (NHG) actively supports and recruits individuals from all segments of society, striving for gender equity and inclusivity including top students and researchers from Canada and abroad. We strongly encourage women and non-binary individuals, Indigenous peoples including First Nations, differently-abled persons, members of visible, cultural and language minorities, the LGBTQ2S+ community, plus other underrepresented and disadvantaged groups to join the team. The NHG has a zero-tolerance policy for discrimination, prejudice, bigotry, misogyny, ageism, and (un)conscious biases as we fully embrace our diverse world.

For the past three decades, Stephen (team lead) has proudly self-identified as gay and queer. He is also a French-Canadian from northern Ontario and therefore part of a language and cultural minority living in British Columbia. With this perspective, the NHG offers a safe space for members of the LGBTQ2S+ community, language and cultural minorities in addition to other disadvantaged and underrepresented groups in science, technology, engineering, the arts and mathematics (STEAM). Indeed, the NHG remains fully committed to ensuring an equitable, inclusive, respectful and supportive work and learning environment. As such, the NHG always assembles a highly diverse group of individuals for which accommodations are made for cultural, family responsibility and faith-based commitments.

Research Group

Past Group Members

Climate change and the water towers of western Canada

Mountains are often referred to as "water towers" as they receive a disproportionate amount of precipitation owing to topographic effects. They also store freshwater in the seasonal snowpack and in glaciers, with these reservoirs providing meltwater that becomes the source of many streams and rivers of western Canada. With growing demands for freshwater resources in a changing climate, there is an urgent need to better understand the role of these water towers in the water cycle of watersheds of western Canada.

The primary goal of this research program is to quantify the changing role of snow and ice in the water cycle of the Quesnel River Basin (QRB), located in the Cariboo Mountains of British Columbia (BC). We aim to establish long-term fluctuations, trends, and feedbacks in the hydroclimate of the QRB using a network of eight weather stations deployed in the area since 2006. These are located at elevations between 750 m and 2100 m, giving information on the air temperature, precipitation, and snow accumulation gradients in this remote region. This program will support the upkeep and expansion (to altitudes >2100 m) of the monitoring network to provide some of the highest, long-term weather stations in BC. This will also yield data on the state and fate of the region's seasonal snowpacks, as these are expected to recede at an accelerating rate with continued warming. This may lead to an amplification of climate change with elevation, due to the positive snow-ice/ albedo feedback on warming. Field data, including those from our sites, combined with satellite products will be used to assess the overall trends and fluctuations in snowpack conditions across the QRB. The sensitivity of snow accumulation and melt to trends to air temperature will be tested to see how it varies with elevation. We will track the timing of snow onset and melt dates, their relation to passages through the freezing/melting point and the ensuing hydrological responses. Placing this work in the larger context of the entire Fraser watershed will give crucial information on the evolution of western Canada's "water towers" in a changing climate.

Floods in the Nechako River Basin

The Nechako River drains 45,000 square kilometres of northern British Columbia (BC) and forms the second largest (by contributing area) tributary of the Fraser River, the province's greatest river by annual discharge at nearly 100 km3. The Nechako remains a highly productive salmon and white sturgeon river, with both fish species vital for local First Nations and other communities. Furthermore, freshwater extracted from the Nechako River and its tributaries is used in many industries within the watershed including agriculture, forestry, and mining. Despite its importance, recent streamflow variability and trends, including information on the occurrence of floods, across the Nechako River watershed are poorly known.

This project's main objective will thus be to examine the annual, monthly and daily discharge data to establish historical flood events along the Nechako River along its main stem and tributaries from 1920 to 2010. Data from a dozen gauges will be extracted from the Water Survey of Canada's Hydrometric Database (HYDAT). Using methods developed previously by the northern hydrometeorology group, hydrological extremes will be assessed at each of the hydrometric gauges. The analysis will first quantify the contribution of each upstream gauged area (nested sub-watersheds such as the Stuart, Nautley and Stellako Rivers) to the total annual discharge measured at Isle Pierre, BC (the furthest downstream gauge operated by the Water Survey of Canada) along with its interannual variability through correlation statistics. Emphasis will be given to the relationship between topography (e.g., elevation, land cover type, etc.), anthropogenic developments (e.g., the Kenney Dam), climatic conditions (e.g., air temperature and precipitation), and observed trends and fluctuations in annual, monthly and daily streamflow in the Nechako watershed. The role of large-scale teleconnections such as the Pacific Decadal Oscillation (PDO) and El Nino/Southern Oscillation (ENSO) on streamflow variability will also be examined. This will yield important information on historical flood frequencies in the Nechako River watershed and allow comparisons with model projections reported in previous studies.

Remote sensing of snow

Since snow covers up to 40% of continental land surfaces in the Northern Hemisphere with significant temporal and spatial variations (Hall 1988), remote sensing of this surface feature becomes practical. Space-borne instruments have the advantage of providing global snow maps at high resolutions. Derived from a single source, this methodology also eliminates possible inconsistencies in measurement taking and archiving, and provides easy access to a global database of snowcover.

NASA's Earth Observing System (EOS) Terra and Aqua spacecrafts, launched in 1999 and 2002, respectively, each carry a Moderate Resolution Imaging Spectroradiometer (MODIS) instrument (Justice et al. 1998). Among other products, MODIS data in the visible and thermal infrared range are used to construct snowcover products. MODIS snow products are available at various spatial and temporal resolutions (Hall et al. 2002). Moderate resolution (5 km) products include 8-day and daily composite tile snow maps whereas at 0.5-km resolution, MODIS snowcover data are available on both regular grids or as a swath covering an area of about 2330 km by 2030 km.

Preliminary work focused on validating MODIS snowcover products for the Kuparuk River Basin of Northern Alaska. It is found that, for a wide range of conditions, MODIS compares well with Landsat imagery in detecting snow. However, current parameterizations for subpixel snow (e.g., Salomonson and Appel 2003) have some difficulty in detecting snow late in the melt period. Through detailed error analyses, we are able to remove these negative biases in the MODIS fractional snowcover estimates. In future work, MODIS snowcover data will be applied to determine the temporal evolution of snow areal depletion curves and to assess the role of subgrid-scale snow in the surface energy and water budgets of Arctic basins.

References

For a complete list of references see my reference list in the data section.

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