CGRG Bibliography of Canadian Geomorphology
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Author : Cheng, Y-C.
Date : 2008.
Title : Tracer study in a large undisturbed soil core.
Publication : 50th Annual Meeting of the Western Division of the Canadian Association of Western Geographers. March 6-8, 2008. Western Washington University, Bellingham, Washington, USA.
Issue :
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Abstract
We present results from tracer experiments in a large (27 cm diameter by 27.3 cm tall) undisturbed soil core from the UBC Malcolm Knapp Research Forest. The salt tracer experiments included both constant tracer applications and a slug tracer test. The conductivity of the soil water was measured at three locations in the core. The conductivity of the outflow water of different segments of the core and total outflow water were also measured. We found large differences in tracer concentrations from different segments of the core. The breakthrough curves were modeled using the advection-dispersion model. Fitted soil water pore velocities were smaller than the constant rainfall rate or the outflow pore water velocity. Both results show the importance of preferential flow in the large soil core. During one experiment, the rainfall intensity was temporarily increased. Our results show that a pressure-wave response occurred and resulted in an immediate increase in the outflow rate. The pressure-wave velocity was 20-50 times larger than the average pore water velocity. Decreases in soil moisture in response to the pressure-wave were also observed. The results of this study show the importance of rapid responses due to preferential flow as well as due to pressure-wave responses.
Bibliography of Canadian Geomorphology