CGRG Bibliography of Canadian Geomorphology
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Author : Grasby, S.E.
Date : 2002.
Title : Application of thermodynamics to examining surface water/groundwater interaction, Bow River Basin.
Publication : Annual Meeting of the Canadian Geophysical Union. May 18-21, 2002, Banff, Alberta.
Issue :
Page(s) :
Abstract
The input of ions into the Bow River is largely controlled by dissolution of carbonate and evaporite minerals. Atmospheric loading can also be a significant source of some ions (e.g. 50% of K, 17% of SO4, 16% of Cl). The chemical denudation rate for the Bow River at Banff is 678 kg/ha/y, or 1.50 x 10 8 kg of rock that is removed as dissolved load each year. An additional 11 kg/ha/y are removed as suspended load. This gives a rock volume of 5.45 x 10 4 m3 that is carried by the Bow River from Banff National Park each year. Despite a 50% drop in total dissolved load from winter to spring discharge, activity ratios of the Bow River are constant, both seasonally and spatially. Activity ratios of the river are distinctly different from precipitation, but are consistent with shallow ground water in the basin. Thermodynamic modeling suggests that equilibrium exchange on smectite has a significant influence on the river chemistry. Mass balance calculations indicate that the amount of smectite in the suspended load is insufficient to control activity ratios in the water. X-ray diffraction analyses indicate that smectite is present and abundant in both the soil and ground water zone, suggesting that precipitation must pass through these zones before reaching the river. This implies that the inverse relationship between total dissolved solids and discharge, common to many rivers, may reflect the residence time of water in the ground before entering the river, rather than simple mixing of ground water with surface runoff.
Bibliography of Canadian Geomorphology