Growing season water balance of wetland reclamation test cells, Fort McMurray, Alberta

Abstract In the oil sands mining region near Fort McMurray, Alberta, strategies to construct wetlands and peatlands and methods to evaluate their success are just beginning. Reclamation of wetlands is particularly challenging in this region as growing seasons are short, precipitation is variable and often limiting, and the presence of elevated salinity associated with the mining process can be harmful to vegetation. As part of their reclamation programme, Syncrude Canada Ltd constructed a series of test plots (termed cells) to examine specific procedures and management strategies associated with wetland reclamation. In this study, water balance of 12 cells (each ~400 m 2 in area) with different soil and vegetation treatments were studied over two growing seasons to understand the influence of soil salvage, vegetation, and placement strategy on water balance components. Cells were constructed in (i) the summer or winter, (ii) with either stockpiled material planted with vegetation or with soils directly transplanted from a nearby wetland and (iii) with soil depths of 15, 50 and 100 cm. Cells were built on a liner to eliminate leakage and were watered using an irrigation system along with receiving precipitation inputs. In 2010, cells were irrigated between ~100 and 400 mm, and water tables were maintained at or near the surface for the duration of the growing season at most cells. In 2011, watering was reduced considerably, and water tables were on average much lower. Evapotranspiration (ET) losses measured using lysimetres varied throughout the season and among cells. ET rates were greater in 2010 than in 2011 because of wet conditions at the surface, and cells placed in the winter and with shallower organic soils (15 cm) also had enhanced ET. Cumulative water balance suggests that some cells had considerable leakage despite being constructed atop a geotextile. Copyright © 2014 John Wiley & Sons, Ltd.