Title

Development of an Areal Snow Depletion Curve in the Dry Creek Experimental Watershed Using MODIS Satellite Imagery and the Utah Energy Balance Snow Accumulation and Melt Model

Publication Date

12-2005

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Geology

Department

Geosciences

Major Advisor

James McNamara

Abstract

An areal depletion curve that relates fractional snow covered area (SCAaf) to snow water equivalent (SWE) is developed using moderate resolution imaging spectroradiometer (MODIS) and the Utah Energy Balance Snow Accumulation and Melt model (UEB). The depletion curve presented here is defined as a graphical representation of the depletion of snow with SCAaf as the y-axis and SWE normalized to the maximum SWE (Wa/Wamax) as the x-axis. The results demonstrate that snowpack heterogeneity within the entire Dry Creek Experimental Watershed is well characterized by the derived depletion curve. Results also indicate that the snowpack has a bimodal distribution in parts of the basin and that snow variability cannot be captured with coefficients of variation alone. UEB results are compared to measured SWE values at Bogus Basin's Snotel site and verify that melt dynamics are well simulated.

Depletion curves are important to present day methods for predicting snowmelt and therefore snowmelt generated runoff in high mountain catchments. MODIS (Moderate Resolution Imaging Spectroradiometer) provides improved capabilities for observing snow cover with mean absolute error less than 0.1, and therefore aids in the development of these depletion curves. Using a normalized difference snow index (NDSI) approach to estimate fractional snow covered area (SCAaf) in 500 m pixels and modeling snow water equivalent (SWE) in 500 m pixels using the UEB snowmelt model, a functional form of a depletion curve is derived for the Dry Creek Experimental. Watershed, Boise, ID. The derived equation is transferable to any given year so that estimates of the water available for runoff can be made.

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