Influence of shallow groundwater-surface water interactions on the hydrological connectivity and water budget of a wetland complex

Linkages between the controls on surface storage and catchment streamflow response were examined in a wetland-dominated basin in the Canadian Prairie Pothole region. Snowmelt, surface storage, water table elevation, atmospheric fluxes, and streamflow were monitored during spring snowmelt and summer in a 1km(2) sub-catchment containing a semi-permanent pond complex connected via an intermittent stream. Snow accumulation in the basin in the spring of the 2013 study year was the largest in the 24-year record. Rainfall totals in 2013 were close to the long term average, although June was an anomalously wet month. The water budget of the pond complex indicates that there was a significant subsurface contribution to surface storage. Activation of an effective transmission zone occurred between uplands and the stream network where the water table was located near the ground surface, which allowed significant lateral movement of subsurface water into the stream network. This was also important for maintaining and re-establishing surface connectivity and streamflow during rainfall events. The observed period of surface-water connectivity was one of the longest on record in the catchment due to unusually wet conditions; nevertheless, the results of this study have implications for how contributing area and runoff should be considered in monitoring and modelling studies in the region, as inclusion of more frequent and varied runoff processes will be essential to understanding changing streamflow regimes. (c) 2015 Her Majesty the Queen in Right of Canada. Hydrological Processes. (c) 2015 John Wiley & Sons, Ltd.