Gatekeeper function of alpine aquifers for the resilience of headwater streams

Abstract:

Groundwater sustains the baseflow of headwater streams and provides the resilience of these systems to meteorological variability. A recent study of high-elevation rivers in the Canadian Rockies showed that the winter baseflow was not sensitive to climate warming over the past half century, suggesting the presence of a buffering mechanism provided by groundwater storage in headwater catchments. Studies in other continents have identified positive correlations between baseflow and the extent of Quaternary sediments covering headwater catchments, indicating that sedimentary aquifers store meltwater from snowcover and glacier, as well as warm-season precipitation, and release it slowly during the cold or dry season. In other words, alpine aquifers serve as a hydrological gatekeeper. Common types of alpine aquifers include moraine, relict rock glacier, talus, alluvial fan, and valley-fill sediment. We will use case studies from alpine hydrological observatories in the Canadian Rockies to examine the gatekeeper function of alpine aquifers for controlling the baseflow hydrograph of headwater streams, as well as their temperature regime.