Name
Hydrological response to the 2017 Elephant Hill wildfire in British Columbia
Description
Wildfire can have a direct effect on stream water quantity and quality and may cause greater risk for flooding, drought, and drinking water treatability in downstream communities. This study focuses on the Elephant Hill wildfire, which burned 1.2 million hectares of forest and grassland on the Interior Plateau of British Columbia in summer 2017. Relatively long-term streamflow records are available, before (2010-2016) and after (2018-2021) the wildfire, in four watersheds in and near the burned area. The quantity and timing of streamflow from two burned (Bonaparte River and Arrowstone Creek) and two unburned (Deadman River and Criss Creek) watersheds were compared using a before-after-control-impact design. Results indicated that post-wildfire annual water yield was 30-46% greater than pre-wildfire water yield in the burned watersheds compared to the unburned watersheds. Average date of maximum daily yield during the snowmelt period was not significantly different before and after the fire except in Arrowstone Creek, the most extensively burned watershed, where maximum flows were 28 days earlier on average. The start of freshet advanced in both burned watersheds. Post-wildfire late summer flows increased 55-88% from pre-wildfire levels in the burned watersheds compared to the unburned watersheds.