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Predictive modeling of moisture movement within soil cover systems for saline/sodic overburden piles



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The research presented in this thesis describes the application of the computer modeling program Soil Cover 2000 as a tool for predicting the soil-atmosphere fluxes and associated moisture movement in a variety of soil cover systems. The four systems examined for this thesis are used to reclaim a saline-sodic shale overburden deposit located at the Syncrude Canada Limited mine site, 40 km North of Fort McMurray, Alberta, Canada. The research represents the second phase of a cover instrumentation and modeling research program. Characterization of the soil cover materials and field responses was carried out during phase one research conducted by Boese (2003) and Meiers (2002). The models were made to simulate field conditions by using multi-modal soil-water characteristic curves and hydraulic conductivity functions, and by estimating the growth of the plant species found on the covers. Computed and measured field response patterns for the four cover systems matched reasonably well for a five month period from May 19 to October 22, 2000. The models were then applied to predict the field measurements for the same period during 2001. Only two adjustments needed to be made to the model parameters in order to simulate the 2001 data; namely changing the dominant vegetation (and related growth parameters) and; adjusting the saturated hydraulic conductivity to match Meiers (2002) field measurements. The calibrated model inputs were used to simulate five cover designs to test their performance during extreme climate conditions. The main objective was to ascertain whether a thinner cover system than the currently recommended cover thickness of 1 m could be effective at the mine. The results indicate that the peat layer is required to minimize the amount of runoff and to decrease the potential for saturated conditions forming at the base of the cover. For a peat-over-till cover system to work effectively, the peat layer needs to be thicker than 30 cm to further reduce the potential for saturated conditions forming at the base. However, thinning the till layer is acceptable since the results show that a thinner till layer has little impact on the performance of the cover. The overall cover thickness needs to be greater than 60 cm to improve plant survival.





Master of Science (M.Sc.)


Civil Engineering


Civil Engineering



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