were appropriated to address Greeley ’ s concern . Other funding sources also are critical for the overall mitigation effort to allow for work in USFS land .
Prioritizing High-Risk Areas
Working in concert with the NRCS , Greeley then hired Ayres as its technical consultant to provide guidance for the work . With no time to waste , the team got to work in late fall 2020 , devising strategies to reach the program goals of improving water quality and protecting life and property and putting these plans into action .
To start , the team established the relative risk of sub-watersheds contributing flow and sediment to the Poudre River , prioritizing those at the highest risk of damage , then targeted those areas for mitigation , said Colin Barry , a geomorphologist at Ayres . The Ayres team used hydraulic models to assess how rain interacts with the burned landscape and transforms into flow , which can flood valleys and impact property . The models help predict and understand post-fire flooding extents and inform mitigation design .
“ Essentially , the more flow you have , the more energy and the more ability for that energy to move sediment ,” Barry explained . Because of the lack of vegetation resulting from the fire , storm events are expected to have significantly greater flows and flooding extents relative to pre-fire conditions . In severely burnt watersheds , hydrologic models indicate that flows can be as much as four times greater in the post-fire environment .
“ Put in another way , the 10-year rainfall event is now the new 100-year rainfall event because of the increase in flow ,” Barry said .
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