A WATER BALANCE OF AN ALPINE CATCHMENT: LAKE O'HARA, YOHO NATIONAL PARK, CANADA

The Lake O'Hara Research Basin is located in the Canadian Rocky Mountains, which is the headwaters for many major rivers in Canada. Snow and glacier melt are the primary contributors to these rivers, with 70% of the mean annual discharge occurring during the high-flow period of May through August. In order to predict the response of mountain rivers to climate change it is important to conduct field studies in small watersheds, which will allow us to understand the physical processes and improve their parameterization in hydrological models. Initial findings indicate that groundwater inflow is 30-70% of total inflow to Lake O'Hara, suggesting that groundwater flow and storage may play a larger role in alpine watersheds than previously thought.

This paper presents the results of water balance calculations in the Opabin sub-basin of Lake O'Hara. Field data collected included snow-water-equivalent, precipitation, glacial melt, stream flow and soil moisture conditions and on-site meteorological data. The objective was to discern whether or not there is a lag between seasonal inputs (snowmelt, glacier melt and summer rain) and surface water outflow. It is hypothesized that the presence of such a lag is a result of storage and release of melt water from surficial geologic material such as moraine and talus deposits, extensively found in alpine areas. Therefore, an improved understanding of the hydraulic characteristics of these materials is required to produce effective watershed model simulations. Future field and modeling efforts will involve characterizing groundwater parameters in alpine hydrologic response units for inclusion in a physically-based distributed model of the watershed.