Base de données de recherche des TNO

Régions: Inuvialuit Settlement Region, Gwich'in Settlement Area

étiquettes: physical sciences, hydrology, ecology, water level, ice jams, nutrient levels, delta floodplain, erosion

Objectif(s): (1) Develop hydraulic model for the channel network of the Mackenzie Delta (Hicks). (2) Field observations of ice jams for calibration and validation of the hydraulic model (Beltaos/Prowse). (3) Assess river ice cover and breakup patterns via satellite image analyses (Vander Sanden). (4) Link an ice-ocean-atmosphere model of Beaufort Sea storm surges to the hydraulic model (Perrie). (5) Measurements of water stored in off-channel areas for testing against hydraulic model (Marsh). (6) Quantification of Mackenzie River nutrient fluxes to the Beaufort Shelf (Lesack).

Description du projet: The Arctic Ocean receives much higher river inflows than other ocean basins and this has major implications for sea-ice formation, for nutrient supply to the base of aquatic marine foodwebs, and for optical properties of ice-free areas and ice-pack margins via fluxes of dissolved organic matter and riverine particles. The Beaufort Shelf is strongly influenced by Mackenzie River outflows. However, Mackenzie nutrient fluxes have been derived from gauging stations upstream of its delta, as has been the case for circumpolar Russian rivers, and does not account for effects that deltas exert on river-borne nutrients. Quantification of nutrient fluxes through such large arctic deltas is very difficult. River discharge through the delta is difficult to quantify during the month-long high-flow period of river breakup and during open-water when backwater effects from the ocean depend on weather and sea ice conditions. Both river ice and sea ice are expected to change significantly in response to climatic warming. The researchers’ investigation of arctic delta effects on riverine nutrient fluxes will be advanced via building on results from 15 yrs of prior research in the Mackenzie Delta. The general goals for this IPY Project include: (1) implementing, refining, and testing an enhanced 1-D hydraulic model of river flow (capable of handling ice-jams and storm surge backflows) through the Mackenzie Delta channel network; (2) field investigations of real-time ice jams and measurements necessary for process-based modeling of ice jams at selected locations; (3) assessing river ice cover and breakup patterns via satellite image analyses; (4) linking the hydraulic model to a model of storm surging effects from the Beaufort coast; (5) incorporating new results into long-term modeling of Mackenzie River flows and potential responses to climatic warming; and (6) improved nutrient characterization of the Mackenzie during breakup and open-water. Results will fill a critical data gap (river discharge and nutrient content) associated with river breakup, allow correct quantification of nutrient fluxes to the Beaufort Shelf, and provide a practical tool for predicting water levels through the Mackenzie Delta as climate continues to change. Specific activities for this field season include the following: (1) Hydraulic network model development - Dr. Hicks plus a research assistant (student) will observe ice breakup patterns (from the air and in association with fieldwork done by Dr. Beltaos (see (2) below), and will be performing various measurements that affect hydraulic flow condition in the river channels, primarily during the May to June breakup period. (2) Ice jam field observations for calibration and validation of the hydraulic model - Dr. Beltaos and Dr. Prowse plus 1 or 2 research assistants will be performing a variety of measurements on ice thickness, ice strength, under-ice roughness, under-ice current velocities, and identifying locations where ice-jamming is most likely to occur, primarily during the May to June breakup period. (3) River ice cover and breakup patterns via satellite image analyses - Dr. Vander Sanden plus a research assistant will observe ice breakup patterns (from the air and in association with fieldwork done by Dr. Beltaos and Dr. Hicks (see (1 and 2), and will be performing various measurements over the river ice that affect optical reflective properties to satellite sensors - primarily during the May to June breakup period. (4) Storm surge modeling for linkage to hydraulic model - Dr. Perrie plus a research assistant will observe the seasonal sea-ice recession pattern (from the air), and may visit some of the WSC gauge sites in the outer delta to ensure the locations will provide data necessary for off-shore storm surge modeling – primarily during August. (5) Off channel storage measurements for testing against hydraulic model - Dr. Marsh plus 1 or 2 research assistants will install small water-level loggers, plus make measurements of channel cross-sections and lake depths, within small delta channels interconnecting among several clusters of lakes, primarily during June through August. (6) Quantification of Mackenzie River nutrient fluxes – Dr. Lesack plus 1 or 2 research assistants will sample river water beneath and amongst the river ice during the May to June breakup, then will regularly sample the delta channel network over the summer from June through September. The water samples will be processed and some time-sensitive analyses will be performed at the Inuvik Research Centre. The researchers will generally publish the results of their work in top-ranked scholarly journals that are subscribed to by the library at the Aurora Research Institute, and will publish some of results in the Aurora Research Institute's plain language publication series. To make research results more accessible to communities in the NWT, they will have a community outreach program. Their Inuvik-based project (IPY-SCARF) is part of a larger IPY project "Arctic Freshwater Systems: Hydrology and Ecology" that will involve scientists working in all parts of the Canadian arctic. This overall project will include a well-developed program of community outreach that will be lead by Chris Spence and Rob Kent of Environment Canada (Tel: 306-975-6907, chris.spence@ec.gc.ca, robert.kent@ec.gc.ca). Inuvik will be a high priority site for community outreach activities. In addition to the above, the researchers will be posting a website that specifically will address their research activities in the Mackenzie Delta (accessed via http://www.sfu.ca/limnology). This will highlight their research and student opportunities for training in arctic-based research. They will also plan on being available to meet with or give presentations to any community groups interested in hearing about their work when they are in Inuvik. Fieldwork will be conducted from May 01 to December 31, 2007 within the Mackenzie Delta.