Refining understanding of hydrological connectivity in a boreal catchment

Literature has long documented how streamflow response in boreal hillslopes and catchments is influenced by storage capacities, thresholds, and landscape and runoff pathway heterogeneity. More recently, the influence these traits have on streamflow has been interpreted through the concept of hydrological connectivity. However, the nature of hydrological connectivity in boreal catchments has only begun to be described. The focus of hydrological connectivity studies at the catchment scale has been on discerning from which areas does runoff originate and when, but not necessarily discovering the source waters of this streamflow. This has been the realm of studies investigating residence time and runoff pathways. This article summarizes an investigation in a 155-km(2) catchment in Canada's Northwest Territories that applied both hydrometric and geochemical methods to measure streamflow response, storage state, connectivity and source waters. The goal of this research was to determine if a catchment scale metric of connectivity could be sensitive to changes in source waters and runoff pathways in a boreal landscape, so as to improve the predictive role of connectivity metrics. Nine runoff events from three water years were evaluated. There were distinct patterns of hydrological connectivity, which included, among others, a non-linear relationship with the runoff ratio and hysteresis with streamflow. The results indicate that one metric of connectivity alone could not encapsulate connectivity extent and quality, identify water sources and be used successfully to predict runoff response. Multiple metrics were needed that further encapsulated the role of precipitation and hydrological processes on both structural and dynamic connectivity. (c) 2014 Her Majesty the Queen in Right of Canada. Hydrological Processes. (c) 2014 John Wiley & Sons, Ltd.