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Spatial simulation of snow and frozen ground using a modified temperature-based model

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dc.contributor.authorFollum, Michael Lee, author
dc.contributor.authorNiemann, Jeffrey, advisor
dc.contributor.authorFassnacht, Steven, committee member
dc.contributor.authorJulien, Pierre, committee member
dc.contributor.authorKampf, Stephanie, committee member
dc.date.accessioned2019-01-07T17:19:19Z
dc.date.available2019-01-07T17:19:19Z
dc.date.issued2018
dc.description.abstractVolume and timing estimates of snowpack and subsequent streamflow are vital for water management and flood forecasting in snow-dominated regions. Numerical models are often employed to estimate the depth of snowpack and presence of frozen ground for assessment of the resulting streamflow. Air temperature based models, such as temperature-index (TI) snow models and degree-day (DD) frozen ground models, are commonly used due to their simplicity and low data requirements. However, because air temperature (a surrogate for available energy) is the main forcing variable, the snowpack and frozen ground in TI and DD models vary spatially based only on elevation. The overall objective of this research is to improve the representation of spatial variations in snowpack and frozen ground within watersheds in order to improve streamflow simulations. To accomplish this goal, this study replaces air temperature in a TI snow model and a DD frozen ground model with a proxy temperature for available energy. The proxy temperature is calculated using a simplified radiation energy balance (requiring precipitation, air temperature, and cloud cover data) that accounts for spatial heterogeneity in both shortwave and longwave radiation due to topography and vegetation. The modified-TI model, referred to as the Radiation-derived Temperature-Index (RTI) snow model, is tested at Senator Beck basin (SBB) in Colorado and at Sleepers River Experimental Watershed (SREW) in Vermont. The RTI model outperforms a pre-existing TI model in simulation of snow water equivalent (SWE) and improves simulation of snow covered area (SCA) at both SBB and SREW. The improvements in snow simulation using the RTI model also improve the streamflow simulation at SBB. The modifications to the DD model, referred to as the modified Continuous Frozen Ground Index (modCFGI) model, also account for insulation of soil by ground cover and simulate frost depth. When tested at SREW, the modCFGI model more accurately captures the variations in frozen ground between the sites, inter-annual variations in frozen ground depths at a given site, and the occurrence of frozen ground than the pre-existing Continuous Frozen Ground Index model. Overall, the modifications made to the snow and frozen ground methods increase the spatial accuracy without requiring much additional data. The RTI and modCFGI methods are also readily transferrable to other hydrologic models.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierFollum_colostate_0053A_15166.pdf
dc.identifier.urihttps://hdl.handle.net/10217/193137
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectfrozen ground
dc.subjectradiation-derived
dc.subjecttemperature index
dc.subjectGSSHA
dc.subjectdegree day
dc.subjectsnow
dc.titleSpatial simulation of snow and frozen ground using a modified temperature-based model
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineCivil and Environmental Engineering
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

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