“Assessing the Risk of Debris Flow Occurrences in Mountainous Recreation Environments Facing Climate Variability: An Application in Glacier National Park”

Laura Engells Texas State University, Department of Geography

OutlineBackground Study QuestionsMethodology Case Study Analysis DiscussionConclusionNext Steps

BackgroundInfluence for the study: Debris Flows in Glacier National Park, Montana: Geomorphology and Hazards, Wilkerson and Schmid, 2003Concerned with the interactions among mountainous environments, natural hazards, and recreation Interest in the interaction between natural processes and human activities

Purpose of Study Update Wilkerson and Schmid’s 2003 study of mountain geomorphology and hazards in Glacier National Park Assess the risk of sites within Glacier National Park to debris flow occurrences Provide park managers with recent data to allow for better emergency management practices

Study Questions What areas are vulnerable to debris flows events within the study area of Glacier National Park?Throughout time, are debris flows randomly or regularly occurring events? What are the environmental impacts of these debris flows? How do these events impact the recreational environment of the park, in particular, how susceptible are hiking trails to debris flow run out?

Study Area

Photo Source: USGS: Climate Change in Mountain Ecosystems, Research Location

MethodologyStep 1: Identify vulnerable recreation sites within Glacier National Park Step 2: Determine bracketing dates for debris flow occurrences Step 3: Measure environmental impact, frequency, and intensity of debris flow occurrences within study areaStep 5: Assess and quantify total trail distance impacted within study area

Analysis: Study Sites

Photo Source: National Park Service, Park Map

Analysis: Utilization of Google EarthView debris flow occurrences with aerial photography throughout Glacier National Park Conduct landscape analysis for debris flow occurrences and run-out Calculate total impacts of debris flow occurrences

Aerial Imagery

Ptarmigan Lake: 1991

Ptarmigan Lake: 2005

Ptarmigan Lake: 2014

Iceberg Lake: 1991

Iceberg Lake: 2005

Iceberg Lake: 2014

DiscussionThere is a regularity of debris flow occurrences within the east side of Glacier National ParkRecreational areas are highly susceptible to debris flow occurrences Impacts to the environment include vegetation loss, scarring on the landscape, and debris flow run-out deposits.

Quantification of Debris FlowsNeed for quantitative analysis to understand debris flows’ impacts on the recreation infrastructure. Two trails were chosen as study sites: Ptarmigan Lake Loop (6,920 meters) and Iceberg Lake Trail (7,725 meters)

Imagery

Ptarmigan Lake Loop

Photo Source: Best Day Hikes, Ptarmigan Loop

Ptarmigan Lake Analysis: 1991

Ptarmigan Lake Analysis: 2005

Ptarmigan Lake Analysis: 2014

Iceberg Lake Trail

Photo Source: Glacier National Park Chat, Iceberg Lake and the trail down to the lake

Iceberg Lake Analysis: 1991

Iceberg Lake Analysis: 2005

Iceberg Lake Analysis: 2014

Results: Quantitative AnalysisPtarmigan Lake Loop: 6,920 meters1991: 370 meters of trail distance were impacted (5.3%)2005: 386 meters of trail distance were impacted (5.6%)2014: 370 meters of trail distance were impacted (5.3%)

Results: Quantitative AnalysisIceberg Lake Trail: 7,725 meters1991: 0 meters of trail distance were impacted 2005: 483 meters of trail distance were impacted (6.3%)2014: 515 meters of trail distance were impacted (6.7%)

ConclusionsDebris flows are regular occurrences in Glacier National Park Integrative approach proved to be a suitable approachImpacted trail distance may be small, but the small trail distances still indicate the presence and threat of debris flow occurrences

Risk Assessment: Next StepsMore risk assessments will be required to collect more data on slope and overall susceptibilityUtilize the data to create a hazard map of debris flow hazards within Glacier National Park

Questions?

Acknowledgements Dr. David R. Butler, for his assistance as my advisor and for the opportunity to study mountain environments and the hazards that occur within them.

Dr. Richard W. Dixon, for his assistance as my M.A.G. committee member

SourcesNational Park Service. 2015. Glacier National Park. http://www.nps.gov/glac/index.htm (last accessed 17 February 2016).Source of 1991 data, USDA Farm Service Agency via Google Earth. 2015. Source of 2005 data, USGS via Google Earth. 2015. Source of 2014 data, Google via Google Earth. 2015.