Long-term Sediment-Phosphorus Dynamics in Wildfire Affected Mountain Streams in Southwestern Alberta, Canada
Abstract
Wildfires can result in increased sediment production from mountain streams, which can produce a range of downstream effects on aquatic ecosystem health and drinking water treatability, amongst other factors. Fine sediments are strongly associated with storage and transportation of phosphorus, which is a key limiting nutrient in many oligotrophic Rocky Mountain streams. While some previous studies have reported increased sediment and phosphorus production for several years after a wildfire, few have explored longer-term post wildfire sediment-phosphorus relationships. This is potentially especially important in northern Rocky Mountain regions where historic glaciation has resulted in a legacy of fine-grained surficial glacial deposits, where fire impacts on sediment-phosphorus relationships could be long lasting.
The Southern Rockies Watershed Project (SRWP) was initially established to document the effects of the 2003 Lost Creek wildfire on hydrology, water quality, aquatic ecosystem health, and downstream impacts including drinking water. Coupled streamflow (Q), coarser sediments (TSS), finer sediments (Turbidity as a proxy indicator), and phosphorus (P) was measured for 11 years after the fire from early spring 2004 to December 2014. Streamflow was measured continuously in 3 burned (Lynx, Drum, and South York Creeks) and 2 unburned, reference watersheds (Star and North York Creeks). This study found that phosphorus production was 3 to 12 orders of magnitude greater in the burned watersheds than in the reference watersheds. Additionally, in contrast to previous studies, the relationships between both coarse and fine sediments and phosphorus with discharge show no clear evidence of recovery for over a decade after the Lost Creek wildfire. Preliminary results suggest similar impacts from the nearby 2017 Kenow Mountain wildfire. This suggests that factors controlling sediment availability and grain size, such as glacial history, are likely key factors governing magnitude and longevity of fire impacts for water quality variables associated with sediment.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H23S2193C
- Keywords:
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- 1813 Eco-hydrology;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 1860 Streamflow;
- HYDROLOGY;
- 1871 Surface water quality;
- HYDROLOGY