USGS is assessing the runoff potential to west Lemmon Valley using modeled snow depth across the basin.The process being used to assess the runoff potential is available in this PDF presentation (51 Mb): Assessment of Potential Runoff to West Lemmon Valley


To determine potential runoff, USGS is

  • modeling snow depth across the basin using long term remote sensing data and recently acquired snow depth data,
  • constraining modeled snow water equivalent to area of snow cover mapped via remote sensing on March 28,
  • converting modeled snow depth to snow water equivalent using recently acquired snow density measurements, and
  • estimating the total volume of water in the snowpack by summing modeled snow water equivalent for all pixels within the watershed

Snow surveying on Peavine Mountain.

Estimated snow depth for Upper Lemmon Valley drainage, constrained to areas of remotely sensed snow covered area.


Estimation of Snowpack Volume

Mean snow density value of 0.446 used to calculate snow water equivalent for all pixels.

For all grid cells: Modeled Snow Depth x Density = Modeled Snow Water Equivalent.

To obtain total volume of water in the snowpack

  • 4745 pixels with snow cover; equivalent to 1055 acres
  • Mean snow water equivalent (snow covered pixels only): 23.3 inches or 1.9 feet of snow water equivalent 1.9 feet x 1055 acres = 2100 acre feet of potential runoff

For more information about Lemmon Valley

Dave Selkowitz

Research Geographer
Landsat Snow Covered Area Science Data Product Team Lead
USGS Alaska Science Center/Nevada Water Science Center