Date of Award:

5-2022

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Civil and Environmental Engineering

Committee Chair(s)

David G. Tarboton

Committee

David G. Tarboton

Committee

Jeffery S. Horsburgh

Committee

Alfonso Torres-Rua

Committee

S.-Y. Simon Wang

Committee

Robert R. Gillies

Abstract

Much effort has been dedicated to expanding hydrological forecasting capabilities and improving understanding of the continental-scale hydrological modeling used to predict future hydrologic conditions and quantify consequences of climate change. In 2016, the National Oceanic and Atmospheric Administration’s (NOAA) Office of Water Prediction implemented the National Water Model (NWM) to provide nationally consistent, operational hydrologic forecasting capability across the continental U.S. The primary goal of this research was to develop hydrological tools that include modeling of flood inundation mapping and snowmelt contributions to river flow in snowmelt-dominated regions across the Western U.S. This dissertation first presents terrain analysis enhancements developed to reduce the overestimation of flooded areas, observed where barriers such as roads cross rivers, from the continental-scale flood inundation mapping method that uses NWM streamflow forecasts. Then, it reports on a systematic evaluation of the NWM snow outputs against observed snow water equivalent (SWE) and snow-covered area fraction (SCAF) at point locations across the Western U.S. This evaluation identified the potential causes responsible for discrepancies in the model snow outputs and suggests opportunities for future research directed towards model improvements. Then, it presents improvements to SWE modeling by quantifying the improvements when using better model inputs and implementing humidity information in separating precipitation into rain and snow. These results inform understanding of continental-scale hydrologic processes and how they should be modeled.

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