Spatial Heterogeneity of Snow Density and Its Influence on Snow Water Equivalence Estimates in a Large Mountainous Basin

Karl Wetlaufer,Jordy Hendrikx,Lucy Marshall

doi:10.3390/hydrology3010003

Karl Wetlaufer, Jordy Hendrikx + Show 1 more

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https://doi.org/10.3390/hydrology3010003

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Journal: Hydrology	Publication Date: Jan 12, 2016
Citations: 19	License type: CC BY 4.0

Affiliation: Montana State University, UNSW Sydney

Abstract

Accurate representation of the spatial distribution of snow water equivalent (SWE) in mountainous basins is critical for furthering the understanding of snow as a water resource, especially in the Western United States. To estimate the spatial distribution and total volume of SWE over mountainous basins, previous work has either assumed uniform snow density or used simple approaches to estimate density. This study uses over 1000 direct measurements of SWE and snow depth (from which density was calculated) in sampling areas that were physiographically proportional to a large (207 km2) mountainous basin in southwest Montana. Using these data, modeled spatial distributions of density and depth were developed and combined to obtain estimates of total basin SWE. Six estimates of SWE were obtained using varying combinations of the distributed depth and density models and were compared to the average of three different models that utilized direct measurements of SWE. Models utilizing direct SWE measurements varied by approximately 1% around their mean, while SWE estimates derived from combined depth and density models varied by over 14% around the same mean. This study highlights the need to carefully consider the spatial variability of density when estimating SWE based on snow depth in these environments.

Highlights

Introduction and BackgroundWater accumulated and stored in the winter snowpack of mountainous regions constitutes a critical source of annual streamflow for much of the Western United States, providing approximately75% of annual discharge [1]
This paper presents a comprehensive field study aimed at modeling the effect of the spatial variability of snow density in estimating total basin snow water equivalent (SWE) for a complex mountainous watershed
The optimal tree size for this model was determined by pruning the tree back to the6).value elevation and radiation to model the spatial distribution of snow density throughout the basin

Summary

Introduction

Introduction and BackgroundWater accumulated and stored in the winter snowpack of mountainous regions constitutes a critical source of annual streamflow for much of the Western United States, providing approximately75% of annual discharge [1]. Improved understanding of how snow water equivalent (SWE) is spatially distributed in mountainous terrain can assist hydrologic models to provide better estimates of total basin SWE and forecasts of the timing, magnitude and seasonal volume of snowmelt runoff. Such information is valuable for a number of applications, such as agricultural planning, reservoir management and flood forecasting, among others. The spatial distribution of SWE can be highly variable in mountainous terrain [2], where its understanding is most critical for quantifying snow as a water resource.

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