Managing Groundwater Resources in Mountainous Areas: Planning for and Adapting to Drought Conditions

Managing Groundwater Resources in Mountainous Areas: Planning for and Adapting to Drought Conditions

Principal Investigator: Diana Allen (Simon Fraser University)

Opportunity: Measuring drought is a complex process, particularly in mountain regions due to their geographic diversity and complex regional microclimates. Drought is commonly subdivided into meteorological drought (rainfall deficit), soil moisture drought (below-normal soil moisture levels), and hydrological drought (below-normal (sub)surface water availability), where “normal” defined by a percentile of the climatology of the variable of interest, and frequency, severity and duration of drought events evaluated. Analysis of previous droughts in British Columbia (BC) indicates that there are three major factors involved with drought occurrence: low winter snow accumulation, spring weather, and summer weather. For drought to occur, often two of the three factors need to exist. The BC Drought Response Plan is organized around four successive levels (Levels 1-4) of drought. BC’s drought indicators refer to the causative factors (snow conditions, spring and summer precipitation, preceding drought) and the resultant factors (stream flow, lake and reservoir levels). Aquifer (groundwater) levels are supplemental indicators, although there are no associated quantitative thresholds.

Objectives: The project aims to fill this gap by partnering with the BC Ministry of Environment and Climate Change Strategy (ENV) to co-analyze historic data (snow, precipitation, streamflow) and groundwater level data from Provincial Groundwater Observation Well Network to evaluate how the groundwater level responses in different aquifers across the mountain regions of BC vary between drought and non-drought years. We will develop quantitative drought indicator thresholds for groundwater level to indicate the level of drought severity.

Research Plan: The project will test the aquifer-related drought indicators in the Okanagan Basin, one of BC’s most water stressed regions. It will then evaluate the regulatory tools (analytical models and lag times) for assessing pumping impacts on Environmental Flow Needs (EFNs) for different drought scenarios in the Okanagan Basin. Finally, it will identify drought sensitive and drought resilient aquifers in the Okanagan Basin using the results of numerical watershed models under historic and future projected climate change.

Key Outcomes & Impact: The outcomes of this project will be used to inform drought management across BC, but the approaches used will be readily adaptable to other mountain regions. The groundwater level indicator thresholds have the potential to serve not only for drought response planning, but also for establishing provincial water objectives. The testing of these indicators and the regulatory tools used by the Province to assess the impact of pumping on in-stream flows in the Okanagan Basin will enable their validation under drought conditions. Finally, the identified drought resilient aquifers in the Okanagan Basin may provide alternative water sources to offset demand during periods of drought.

February 2020 Presentation: Building Resilience During Drought

Other Team Members:
Tom Gleeson (University of Victoria); Carl Mendoza (University of Alberta)