Process-based diagnosis of recent variations in streamflow in an alpine glacierized catchment
Abstract
Most mountain glacierized headwaters are currently witnessing a transient shift in their hydrological and glaciological systems in response to climate warming. To characterize these changes, a robust understanding of the micrometeorological, hydrological and glaciological processes at play in the catchment and their interactions is needed. An investigation of the processes occurring in a glacierized headwater catchment in the Canadian Rockies, Peyto Glacier Research Basin, was conducted using observations and diagnostic modelling for a 27 year period (1990-2017). A distributed, physically-based glacier hydrology model was designed using the Cold Region Hydrological Modelling Platform to simulate both on and off-glacier high mountain hydrological processes so as to diagnose change. The model spatial configuration was shifted to accommodate glacier retreat and changing land cover in the basin. The model was validated with streamflow, snowpack and glacier mass balance observations. Over the 27-year period, no statistically significant trends were detected in the driving meteorology or the streamflow response using the Mann-Kendall test (p = 0.05) and inter-annual variability dominates the streamflow response in the catchment, leading to both variable annual streamflow and streamflow composition. Snowmelt always provides the largest volume to annual streamflow (49-80%) while ice melt provides between 17 to 37% of annual streamflow. Both rainfall runoff and firn melt contribute less than 10% of annual streamflow. Comparing high and low streamflow years reveals that high streamflow years are on average 1.1°C warmer than low streamflow years with 33% more rain than low flow years, but with similar snowfall. This combination of warmer temperatures and increased rainfall causes earlier snowmelt, enhanced ice melt and increased late summer rainfall runoff, causing a total difference of 34% in annual streamflow volume between high and low flow years.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C23C1556A
- Keywords:
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- 1621 Cryospheric change;
- GLOBAL CHANGE;
- 1630 Impacts of global change;
- GLOBAL CHANGE;
- 4329 Sustainable development;
- NATURAL HAZARDS;
- 4333 Disaster risk analysis and assessment;
- NATURAL HAZARDS