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LABORATORY TESTING PROGRAM FOR THE PREDICTION OF RAINFALL RUNOFF FROM SOIL COVER SYSTEMS
Session: Laboratory Testing II / Essais en laboratoire II
Ahlam Abdulnabi, University of Alberta (Canada)
G. Ward Wilson, University of Alberta (Canada)
Soil covers are commonly utilized to prevent Acid Rock Drainage (ARD). The design is governed by the net infiltration into the system. Infiltration prediction models require calibration using water balance controls. This requires rainfall runoff measurements, yet, such measurements are rarely available. Alternatively, accurate predictions of rainfall runoff for soil cover systems facilitate the calibration procedure. A laboratory-testing program was developed to formulate a reliable model to predict rainfall runoff for soil covers. Both single layer and multi-layer soil profiles were tested in a specially designed rainfall simulator apparatus. Simulated precipitations of different intensities on different initial conditions were conducted. Runoff volumes were measured simultaneously with rainfall volumes. In addition, a number of instruments were installed to monitor changes in matric suction and volumetric moisture content as the wetting fronts propagated. Results suggest that rainfall runoff rate is primarily governed by the applied rainfall intensity and saturated hydraulic conductivity in the case of saturated soil surfaces, whereas it is governed by the applied rainfall intensity and infiltration capacity for unsaturated soil profiles.
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