Forest Disturbances and Wildfires
In the western US, wildfires are natural and regular occurrences. Increasing wildfire intensity, size, and proximity to urban development within the last decade requires more understanding of post-fire processes The Hogue Hydrology Research Group has been investigating forest disturbance for 10 years. Studies include post-fire geochemistry, modeling, remote sensing, and field work. We also investigate post-fire watershed scale ecohydrologic response and recovery through in-situ instrumentation as well as remote sensing applications to better understand post-fire biomass recovery, long term low-flow (or baseflow) response and recovery, changes in spatial snowcover patterns, and effects on overall water quality and quantity.
WORK IN THIS AREA INCLUDES:
- 2003: Old Fire (San Bernardino Mts., CA) – Nutrient loading, chemical response, flow regimes (Jung et al., 2009); Post-fire flood modeling (Cydzik and Hogue, 2009); Watershed recovery (Kinoshita and Hogue, 2011)
- 2005: Topanga Fire (Malibu Canyon) and Pines Fire (Arroyo Seco)
- 2006: Day Fire (Piru Creek-Pyramid Reservoir) – Mercury transport (Burke et al., 2010)
- 2009: Station Fire (Angeles NF, Arroyo Seco) – Impaired water quality (stream, reservoirs, soils): metals, nutrients, sediments at the urban-fringe (Stein et al., 2012; Burke et al., 2013; Kinoshita et al., 2013 (in review))
- 2010: Bull and Canyon Fires (Sequoia National Forest)– USFS collaboration – Rainfall-runoff response, coupled vegetation recovery (Hale, 2012 M.S. Thesis)
- 2011: BAER Model Comparison and Remote Sensing Study – USFS collaboration – Ground truthing remote sensing vegetation indices (Clark et al., 2012); BAER model inter-comparison (Kinoshita et al., 2013 (in revision)); USFS GTR (in press))
- 2012: Waldo Canyon Fire (Pike National Forest) – WUI post-fire response, flood model improvements
- 2013: West Fork Complex (San Juan and Rio Grande National Forests) – Post-fire geochemistry in gold medal trout water
- 2013: Rim Fire (Stanislaus NF and Yosemite NP) – Post-fire geochemistry of Lakes and Reservoirs for SF water supply
- Sagehen Experimental Forest (Tahoe National Forest)– Impact of fuel treatments on water yield
POST-FIRE WATER QUALITY
The Joint Fire Science Program (JFSP) is supporting a project to investigate post-fire water quality impacts. The project is titled, “Post-fire Water Quality: an Investigation of Determinants and Recovery Processes in Burned Watersheds across the Western U.S.” The principal investigator on the project is Dr. Terri S. Hogue and the Co-Principal Investigator is Dr. John E. McCray, both with Colorado School of Mines Hydrological Sciences and Engineering program. Our goal is to build a fire database that will include water quality data from each burn impacted watershed, with data from 10 years before the fire and 5 years after the fire. Other studies have shown that a proximity to regional pollutants drives post-fire water quality response on the watershed scale and that metal concentrations increase in municipal water supplies post-fire. We hope to examine these trends across multiple fires. We will also gather data from water treatment plants in burn impacted watersheds to assess the levels of dissolved organic carbon and resultant formation of disinfection by-products.
The database will also hold spatial geophysical data from burn impacted watersheds. We want to identify key drivers of short and long term water quality response, ultimately identifying the watershed characteristics that improve resiliency to fire. This project will also utilize and improve current hydrochemical models such as USDA’s SWAT and the Watershed Analysis Risk Management Framework (WARMF) to better predict post-fire water quality response.
Sagehen is an Experimental Watershed in the Tahoe National Forest in California. It will be the prototype for the Sierra Nevada Forest Management. Unhealthy buildup in the forests contribute to catastrophic fires and strategically placed treatments will be implemented to bring back a natural and healthy forest. We will evaluate and regionally scale the response of the proposed forest treatments on hydrologic fluxes in Sagehen to understand the impacts on water yield and snow dynamics.
- The Rim Fire is the third largest fire in California’s history and is one of the largest in the Sierra Nevada.
- It burned 257,314 acres since it’s ignition on August 17, 2013 including part of Yosemite National Park.
- The mitigation cost to date is $127.35 million and $4.3 million will be used towards watershed treatment to mitigate potential downstream impacts.
- The Rim Fire threatened the O’Shaughnessy Dam and reservoir in the Hetch Hetchy Valley, which supplies water for the San Francisco Bay Area.
- It also has the potential to impact the Tuolumne River water system, which supplies water to San Francisco and 29 other wholesale buyers in San Mateo, Santa Clara, and Alameda counties.
An NSF RAPID proposal was recently awarded to Professor Hogue and co-PIs to investigate the potential impacts on water quality in the Rim Fire area. RAPID proposals allow quick-response research on natural or anthropogenic disasters and similar unanticipated events. The project is also supported by funds from the NSF Engineering Research Center on Urban Water Infrastructure ReNUWIt. Research will involve monitoring reservoir and regional stream system water quality as well as alterations in snow patterns and associated spring runoff.
WALDO CANYON FIRE
- Colorado experienced two severe and deadly wildfires during the 2012 summer season.
- The Waldo Canyon fire occurred along the urban interface near Colorado Springs, the Air Force Academy, Manitou Springs, Green Mountain Falls, Cascade, and Chipita Park, burning over 18,000 acres and 360 homes.
- The fire was the most expensive in Colorado’s history, resulting in over $350 million in insurance claims and over $16 million in fire suppression costs.
- Emergency mitigation treatments include about 3000 acres of treated land (aerial agricultural straw mulch and woodshred mulch), 16 miles of road storm proofing, 8 miles of trail stabilization, and abundant protection and safety signage and closures.
The Hogue Research Team is investigating short- and long-term hydrologic response in the Waldo Canyon Fire area and the impacts that post-fire climatology, treatment, burn severity, geophysical parameters, and vegetation dynamics have on post-fire recovery. We ultimately hope to improve insight on hazard mitigation at the urban fringe and advance management and resource decisions after fire
Contaminant loading associated with stormwater runoff from recently burned areas is poorly understood and has the potential to affect downstream water quality. The Hogue Hydrology Group studied and assessed regional patterns of runoff and contaminant loading from wildfires in urban fringe areas of southern California.
- Observed post-fire concentrations and loads up to three orders of magnitude greater than pre-fire values for many trace metals, including lead and cadmium.
- Shift in the timing of chemical delivery, where maximum suspended sediment, trace metal, and cation concentrations coincided with, rather than preceded, peak discharge in the post-fire runoff, amplifying the fire’s impacts on mass loading.
- Contaminant loading from burned landscapes has the potential to be a substantial contribution to the total annual load to downstream areas in the first several years following fires Relevant Publications Burke et al., 2013 Stein et al., 2012 Burke et al., 2010 Jung et al., 2009
Wildfires alter land surfaces and land-atmosphere interactions, enhancing hydrologic responses such as flooding and debris flows. Accurate prediction of post-fire events is important for efficient mitigation. The US Forest Service (USFS) Burn Area Emergency Response (BAER) teams are required to estimate post-fire runoff and sediment fluxes in areas that have values at risk or threaten human life and natural resources. Current research focuses on providing specialists and policy makers with guidance on tools to assist in post-fire hydrologic monitoring and management, both pre- and post-fire. Models assessed:
- Rowe Countryman and Storey
- USGS Regression
- USDA TR-55
- Army Corps HEC-HMS
This suite of models is then applied to a diverse set of sites affected by wildfire in the western United States to estimate peak flow events (pre- and post-fire).
POST-FIRE HYDROLOGIC MONITORING AND VEGETATION VALIDATION
In collaboration with the USFS, our field work in post-fire environments includes hydrological monitoring of various basins in the 2010 Bull Fire (southern Sequoia, CA) to validate post-fire models. Ground-based measurements (tipping buckets and pressure transducers) provide data to develop high resolution precipitation and streamflow timeseries. These visits also provide opportunities to validate remote sensing of post-fire environments. Remote sensing has greatly improved techniques for acquiring and studying variables in ungauged and large spatial areas and is used to monitor recovery conditions by agencies interested in post-fire management. A photo interpretation method is used to quantify the vegetation coverage present in situ and compared to remotely-sensed vegetation indices (Clark et al., 2012).
REMOTE SENSING POST-FIRE HYDROLOGIC RECOVERY
Current management practices are primarily concentrated around immediate post-fire effects (first storm season); however, burned systems are altered for prolonged periods of time. Estimating the changes in hydrology as a result of upstream landscape alterations and the uncertainty of post-fire recovery and behavior is critical for downstream communities. Our previous work in southern Californian watersheds shows geophysical values (easily obtained through remote sensing techniques) and lack of vegetation recovery are related to significant changes in annual and seasonal discharge for seven years post-fire. Applying remotely sensed data streams in post-fire environments facilitates monitoring of large and ungauged areas at high spatial and temporal resolutions; providing important information affecting recovery. Current work strives to integrate spatial and temporal variability indicated by remote sensing data from multiple satellite platforms to improve prediction of hydrological variables and vegetation that control post-fire response.