Assessment of precipitation and snowcover in northern research basins^*

In 2004, a workshop was held to collect and synthesize the water balance data from 39 northern research basins (NRB) in Victoria, BC, Canada. One of the recommendations from the meeting was a need to review systematically each component of the water balance for these northern basins in order to identify spatial and temporal trends and to address significant knowledge gaps. Here, we assess the methodologies for measuring snow and rain in these northern basins; examine the temporal and spatial patterns of snow accumulation both during and at the end-of-the winter; consider ablation patterns and comment on the occurrence of extreme events. Our evaluation indicates that northern hydrologists still employ a variety of gauges and approaches to both measure and correct precipitation. For the NRB, rainfall contributions dominate in lower latitudes while snowfall gains importance with higher latitudes and altitude. Occurrence of large water bodies, topography (i.e. aspect, slope) and vegetation influence precipitation amount and its distribution across the landscape. Only two NRB studies showed a declining trend in snowcover (SWE). Snow is still considered the most important input of water in these northern basins, but extreme summer precipitation events (both rain and snow) have triggered higher magnitude floods than seasonal snowmelt runoff. Glacierized basins are sensitive to summer snowfalls and low winter snow storage. Both have the potential to dampen or enhance melting despite warmer or cooler air temperatures. Standardized gauges, approaches and continued monitoring of the NRB is encouraged.