Use of water stable isotopes for evaluation of surface water/groundwater interaction during a storm event at the Alder Creek watershed, Southern Ontario

A study of the interaction between groundwater and surface water was undertaken within a small agricultural watershed at Mannheim, southern Ontario, Canada. The study was conducted in a test site managed by the University of Waterloo. Groundwater contribution to the stream was measured along a section of Alder Creek during a rainfall event. After a general characterization by water stable isotopes, the hydrograph separation has been conducted using 18O/16O isotopic ratios before, during and after the rainfall event recorded the fourteenth of July 2015. The elaboration showed that pre-event water (corresponding to groundwater contribution) dominated the streamflow, accounting for 82% of discharge, respect with 18% of event water (precipitation) recorded during the storm flow peak.