Lake Diefenbaker temperature model

Many water quality processes in lakes and reservoirs are temperature dependent. Water temperature affects stratification and mixing, dissolved oxygen solubility, biological and physiological processes and aquatic species tolerances. Anticipated increases in air temperature due to climate change may also influence in-lake processes. In order to make valid predictions regarding the impact of climate change on the thermal structure of Lake Diefenbaker and determine the potential effects of management strategies, a hydrodynamic model was utilized for the period 2011-2012. Lake Diefenbaker is a long (181 km) and narrow (average width of 2.2 km) reservoir in Saskatchewan, Canada formed along the South Saskatchewan River (SSR) by the construction of the Gardiner and Qu'Appelle River dams in the 1960s. The model was calibrated using Monte-Carlo and combined global and local optimization techniques, which provided insights into parameter sensitivity and identifiability of relevance to monitoring needs. A new ice algorithm was also used, incorporating the effect of snow on the ice surface. In particular, this study provides a novel quantitative analysis of the contribution of different heat sources and sinks to the lake's heat budget, providing invaluable information for reservoir management practices in response to climate change and uncertainty. Of particular interest is the high input of heat from the lake's main inflow, the South Saskatchewan River, which has a high impact on the heat budget.