The multifaceted impact of glacier retreat on water resources
Abstract
Once a mountain glacier begins retreating, discharge at the watershed outlet increases until a peak is reach. After this point, glaciers start losing hydrological influence as their surface become too small to sustain release of high melt water volumes. This sequence, known as peak water, is well accepted as describing the overall impact of glacier retreat on water resources. Beyond that macroscopic, coarse description, glacier retreat impacts on water resources exhibit a complex, variable, multifaced character. We here propose an overview of the main learnings arising from the research we conducted in glaciered catchment in the tropical Andes and in Canadian Subarctic over the past 20 years. Because glaciers are not the only contributor to glacierized catchment outflows, impacts of glacier retreat on water resources is influenced by the hydrological behavior of other sources. For instance, we observed measurable groundwater contribution to glacierized watershed outflows at all our study catchments. Contribution from other sources such as buried ice, seasonal snow cover, and surface runoff was observed too. Those sources differ from region to region and their level of contribution vary from watershed to watershed within a given region. The relative contribution of these non-glacial sources generally increase as glaciers looses mass and hydrological influence at the watershed scale. Moreover, our observations show complex and variable interactions between the different water sources in glacierized catchments: aquifers are usually both melt and rain fed and loosing and gaining sections of a proglacial stream can alternate over short distances. These complex interactions, usually not accounted for in hydrological projections, make hydrological transformation complex and difficult to anticipate. The glaciers retreat impacts on water quality shows even more complexity. This type of impact is even more difficult to anticipate as the evolution of the pollutant concentrations in glacierized catchment depends on multiple factors, some being influenced by glaciers (water temperature, water volumes or suspended) some not (lithology, mining, ...). Overall, we argue that a lot remains to be done to move away from macroscopic, coarse projection of glaciers retreat impacts on water resources over the coming decades
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H25S1242B