Jason Welz

Jason Welz

Degree(s) Held

B.S., Environmental Studies, University of California, Santa Barbara,1996

Degree Sought:

M.S. in Earth Sciences

Title of Research Project:

Function of Avalanches on the Spatial Distribution of Snow and the Timing and Magnitude of Snowmelt Runoff

Advisor:

Jordy Hendrikx

Email Address:

jasonwelz@gmail.com

Research Project Summary

My research is motivated by the importance of snowmelt as a vital water resource for the majority of the semi-arid montane ecosystems and communities in the U.S. Intermountain West. While the amount of water available in a regional snowpack has been examined through operational snowmelt runoff forecasting since the early 20th century, there is still a limited amount of understanding about exactly how and why this resource is distributed throughout a watershed and how it is becomes part of the hydrologic network. To explore this scenario, a study has been designed to investigate some of the dominant processes and topographic characteristics that influence snow distribution in alpine basins, with a particular focus on avalanches. The end result will be to quantify the impact each of these variables have on the stream discharge hydrographs of two adjacent alpine basins in southwestern Montana: one avalanche-prone and one avalanche-free.

  • Main Research Question:

Do avalanches play a significant role in timing and magnitude of snowmelt runoff in alpine basins?

  • Sub-question:

Is the hydrologic role of avalanches insignificant compared to the variables of wind drifting, aspect, and net radiation?

Study Area

A study site with the topographic characteristics appropriate for assessing the above research questions has been chosen near Cedar Mountain in the northern Madison Range near Big Sky. This comprises two adjacent alpine basins with similar aspects, tree/shrub cover, and area (1.38 and 1.62 km2). Primary differences in slope angle and dominant topographic features are believed to separate the basins into being avalanche-prone and avalanche-free (control). 

NE facing headwall

View of the avalanche-prone basin showing the steep NE facing headwall thought to be a dominant feature that will promote frequent sloughs and occasional slab releases. Photo was taken on November 1, 2012.

control basin

View of the control basin showing the more gently sloped terrain that, combined with additional wind scour compared to the avalanche basin, is thought to limit avalanche activity. Photo was taken on November 1, 2012.

Sampling Strategy and Instrumentation

Snow depth and snow water equivalent (SWE) are the variables that will be sampled to determine the pattern of snow distribution in each basin. These will be measured periodically throughout the period of accumulation to capture significant influential events and more intensely during the period of ablation to relate the declining pattern of the snowpack to the variables affecting distribution and their subsequent effect on stream discharge. Sampling of snow depth and SWE will be performed at transects along elevation contours to capture the prominent topographic features related to the snow distribution variables of each basin.

To capture avalanche activity and develop a time-series photo log of the pattern of snowpack decline, an automated camera was installed facing the avalanche-prone basin on December 17, 2012. On the same day, an anemometer was also installed at mid-elevation on the ridgeline separating each basin to collect input data for quantifying wind-drift. Aspect has been modeled with a 1 m grid LiDAR and net radiation initially with a 30 m grid DEM (to be enhanced by 1 m grid LiDAR), to determine these inputs. Water level data loggers were installed at the lowest point in the main stream channel exiting each delineated basin on November 1, 2012, to begin recording stream height several times daily. These automated measurements will be combined with periodic manual streamflow discharge measurements to develop a stage-discharge curve for determining discharge during periods of no observation. Through this process a hydrograph will be developed for each basin.

Proposed Timeline

Fieldwork will be conducted throughout the winter and spring of 2013, and is anticipated to be concluded by the end of June 2013 depending on seasonal conditions.