riveri1.gif (87364 bytes) Over-winter isotopic variations in discharge from river-ice archives: A study funded by the National Water Research Institute (NWRI at NHRC) and CAGES (Canadian GEWEX Enhanced Study)

Collaborator: Dr. T.D. Prowse (NHRC, Saskatoon)

Excerpt from October 1998 Progress Report

Isotope stratigraphy of river ice is also being developed as an ancillary activity of Liard River MAGS investigations. As shown in the figure below, reliable reconstruction of over-winter isotopic composition of streamflow from ice archives has been achieved. This novel technique will serve to extend partitioning studies into the winter season to study the groundwater recession characteristics in each of the five study basins. The ice-on period is characterized by a gradual decline in total discharge. As shown for the Blackstone River, decline in discharge is accompanied by a

prominent isotopic shift to compositions reflecting winter baseflow (groundwater only). A partitioning analysis of surface water versus groundwater contributions will be used to gain a better understanding of freeze-back processes which are poorly known in discontinuous permafrost terrain.

Time-series of streamflow d18O in the Blackstone River for 1997-98 based on water sampling and isotope stratigraphy. Recontruction of water compositions from ice assumes a constant ice-water fractionation of 2.91‰ based on field evidence obtained by Gibson and Prowse, in press.

Back