Climate Change and Drought Management in the Okanagan Basin, British Columbia: Opportunities for Translation

Two recent case studies link global climate change scenarios and regional water resources planning in the Okanagan Basin, British Columbia, Canada. The Okanagan is a semi-arid region which experienced a severe drought event in 2003. It has been the subject of several climate change studies specifically focused on defining potential changes in future risks to regional water resources. The challenge is to address potential changes in both supply and demand due to future changes in climate, population, and land use, and to create learning opportunities in which response options can be evaluated for future scenarios. This requires translation of changes in climate indicators to changes in water management outcomes.

Both case studies included development and application of decision support tools that quantitatively link climate, hydrology, water supply, water demand, and management actions. The first was an integrated, system dynamics model (using STELLA^TM software) constructed within a collaborative stakeholder process to address basin-scale aspects. The second focused on a sub-basin watershed serving the town of Peachland, and employed the WEAP model. The two cases differed in spatial and temporal resolution, and address somewhat different management questions. In the Peachland study, WEAP, an integrated water management model, was used to consider future scenarios for water supply and demand for an unregulated and for a reservoir-supported stream. The management components included an assessment of reservoir release strategies, and also assessed how well they could achieve in-stream flow requirements for supporting aquatic ecosystems. The basin-scale study included multiple management options for increasing supply or decreasing demand, and described the resulting reliability over the simulation period under different scenarios. In the two cases, selected climate change and population growth scenarios for the region are shown to negatively impact water supply reliability; however, certain management options could compensate and improve outcomes, thereby enabling adaptation to future climate change and population growth.