CGRG Bibliography of Canadian Geomorphology
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Author : Birks, S.J.; and Edwards, T.W.
Date : 2004.
Title : Development of the 1997 Red River Flood: New insight from water isotope data.
Publication : Eos Transactions. Joint Assembly of the CGU, AGU, SEG and EEGS, Montreal, Canada, May 17-21, 2004.
Issue : 85(17):
Page(s) : H21A-04.
Abstract
During the spring of 1997 near record winter snowfall on the Red River basin combined with frozen soils and a rapid spring melt resulted in extensive flooding in North Dakota and Manitoba. Floodwaters were sampled from the Red River at four locations around Winnipeg and analysed for major and minor ions, and organic contaminants. Here we present new oxygen and hydrogen data for floodwaters sampled in the vicinity of Winnipeg prior, during and after the main peak of the 1997 flood and review the geochemical data in light of the information the isotopic composition of the water can provide about the source and history of the water. The depleted delta values, and relatively high d-excess measured in Red River samples from the ascending arm of the 1997 seasonal hydrograph support the interpretation from the very dilute geochemistry that the waters at the beginning of the flood originated as winter precipitation. As the main peak of the flood reached Winnipeg the isotopic composition of floodwaters remained within the range of winter precipitation while concentrations of some organochlorine and pesticides reached maxima. After the main peak of the hydrograph the specific conductivity of the floodwaters increased, with minor increases in dissolved major ions typical of groundwater, decreases in nitrate and nitrite, and increased potassium concentrations. During the falling limb of the snowmelt hydrograph the geochemical and isotopic composition of the floodwaters both indicate a greater proportion of groundwater. Combining geochemical indicators of surface water history with isotopic indicators of water source and history allows for qualitative interpretation of the evolution of floodwaters in the Red River. In this area of extremely flat topography and low permeability sediments the isotopic composition of floodwaters generated after spring melt are consistent with meltwater inputs dominating through the rising limb and peak of the flood hydrograph.
Bibliography of Canadian Geomorphology