CFA Wildfire Workshop 2019 Presentation – Tim Giles

Mitigating Mass Wasting and Downstream Impacts
Tim Giles – Research Geomorphologist, FLNRORD

ABSTRACT: The 2017 Plateau Fire affected 435,765 hectares (35%) of the Blackwater River and 30,260
hectares (18%) of the Narcosli Creek watersheds. An initial reconnaissance assessment indicated that there
were limited steep slope natural hazards but that there was a significant threat from the expected
hydrologic response. This spurred FLRNRORD to complete post‐wildfire hydrologic risk assessments of
these watersheds.
The assessments included review of water repellent (hydrophobic) soils, pre‐fire forest disturbance, fire‐
related forest disturbance, post‐fire flood hazard, spring (2018) freshet, elements‐at‐risk, fire‐related
riparian disturbance, post‐fire sediment yield potential, post‐fire channel response potential and overall
post‐fire hydrologic risk.
Recommendations include spring 2018 flood potential, update burn severity mapping, future ECA
modelling, assess the presence of hydrophobic soils (summer 2018), review riparian disturbance (summer
2018), review potential soil erodibility (summer 2018), review channel stability (summer 2018), floodplain
mapping and refinement of list of potential elements‐at‐risk, long‐term flood and erosion mitigation, and
hydrometric monitoring.

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