Huang, M., Barbour, S. L., Elshorbagy, A., Zettl, J. D. and Si, B. C. 2011. Water availability and forest growth in coarse-textured soils. Can. J. Soil Sci. 91: 199–210. A method of evaluating the influence of soil layering and climatic variability on plant available water for forest growth is presented. This method enables species-specific levels of maximum sustainable plant transpiration to be evaluated. A calibrated HYDRUS-1D model was used with a 60-yr meteorological record to simulate actual evapotransipration (ETa) of dominant tree species with different values of leaf area index (LAI) for three sites in northern Alberta. A probability distribution of ETa was developed for each case. The relationships between LAI, plant above-ground primary production (ANPP), and ETa were used to estimate the minimum water demand to support plant growth at specific sites. The developed frequency curves of ETa and the minimum water demand can be used to determine the maximum sustainable LAI and the risk associated with revegetating a particular site with a dominant tree species. The effect of different tree species on the minimum water demand and the maximum sustainable LAI was also illustrated. The results indicated that layering of coarse-textured soils can provide more plant available water and support a higher maximum sustainable LAI than homogeneous soils of a similar texture.

Huang, M., Elshorbagy, A., Barbour, S. L., Zettl, J. D. and Si, B. C. 2011. System dynamics modeling of infiltration and drainage in layered coarse soil. Can. J. Soil Sci. 91: 185–197. A system dynamics (SD) model was developed to simulate transient infiltration and drainage processes in multilayered soils. STELLA Software was used as a stock-flow icon-based simulation environment. The developed SD model combined both physically based formulations and empirical assumptions to describe one-dimensional saturated–unsaturated water flow in the vadose zone. The model was successfully calibrated and validated using measured water contents during the infiltration and drainage phases, respectively, of a double-ring infiltration test. The simulation results were also compared with a finite element model of saturated/unsaturated flow (HYDRUS). The results showed that the SD model was capable of accurately simulating the various hydrological processes in multilayered soils, and could be a useful tool for designing reclamation covers. The simulated and measured results show that the presence of a finer sand layer overlying a coarse sand layer will increase the soil water storage at field capacity.

, S. L. 2015. An evaluation of air permeability measurements to characterize the saturated hydraulic conductivity of soil reclamation covers. Can. J. Soil Sci. 95: 15Á26. The saturated hydraulic conductivity (K s ) of soil covers used in land reclamation is known to change over time as the result of weathering processes. Guelph permeameter (GP) measurements have been used to track the evolution of K s for soil covers at an oil sands mine near Ft. McMurray, Alberta. Although successful, the method was time consuming and consequently a rapid method of estimating K s based on in situ air permeability measurements was developed. The objectives of this study were: (1) to use air permeability measurements to characterize the spatial variations of K s for typical reclamation soils and (2) to compare air permeability measurements to direct measurements obtained through laboratory and GP measurements. The results highlight that the values of K s estimated from measured air permeability values were higher than the values of K s measured directly using the GP. This is likely due to swelling of clay soils or air-entrapment during GP measurements. Although the magnitude was over-estimated, the variability of K s was captured by the air permeability measurements. Consequently, a limited program of comparative GP and air permeameter measurements could be used to more rapidly characterize the K s of reclamation covers over time.