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Date Permissions Signed

5-1-2010

Date of Award

2010

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

Mitchell, Robert J. (Geologist)

Second Advisor

Clark, Douglas H., 1961-

Third Advisor

Bunn, Andrew Godard

Abstract

The Nooksack River has its headwaters in the North Cascade Mountains and drains an approximately 2300 km2 watershed in northwestern Washington State. The timing and magnitude of streamflow in a high relief, snow-dominated drainage basin such as the Nooksack River basin is strongly influenced by temperature and precipitation. Forecasts of future climate made by general circulation models (GCMs) predict increases in temperature and variable changes to precipitation in western Washington, which will affect streamflow, snowpack, and glaciers in the Nooksack River basin. Anticipating the response of the river to climate change is crucial for water resources planning because municipalities, tribes, and industry depend on the river for water use and for fish habitat. I combined modeled climate forecasts and the Distributed-Hydrology-Soil-Vegetation Model (DHSVM) to simulate future changes to timing and magnitude of streamflow in the higher elevations of the Nooksack River, east of the confluence near Deming, Washington. The DHSVM is a physically based, spatially distributed hydrology model that simulates a water and energy balance at the pixel scale of a digital elevation model. I used recent meteorological and landcover data to calibrate and validate the DHSVM. Coarse-resolution GCM forecasts were downscaled to the Nooksack basin following the methods of previous regional studies (e.g., Palmer, 2007) for use as local-scale meteorological input to the calibrated DHSVM. Simulations of future streamflow and snowpack in the Nooksack River basin predict a range of magnitudes, which reflects the variable predictions of the climate change forecasts and local natural variability. Simulation results forecast increased winter flows, decreased summer flows, decreased snowpack, and a shift in timing of the spring melt peak and maximum snow water equivalent. Modeling results for future peak flow events indicate an increase in both the frequency and magnitudes of floods, but uncertainties are high for modeling the absolute magnitudes of peak flows. These results are consistent with previous regional studies which document that temperature-related effects on precipitation and melting are driving changes to snow-melt dominated basins (e.g., Hamlet et al., 2005; Mote et al., 2005; Mote et al., 2008; Adam et al., 2009).

Type

Text

DOI

https://doi.org/10.25710/d4c6-e376

Publisher

Western Washington University

OCLC Number

649820581

Subject – LCSH

Hydrological forecasting--Washington (State)--Nooksack River Watershed; Climatic changes--Washington (State)--Nooksack River Watershed--Forecasting

Geographic Coverage

Nooksack River Watershed (Wash.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

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