Date of Award

2020

Document Type

Thesis

Degree Name

M.A.

Department

Geography

First Advisor

J. Michael Daniels

Second Advisor

Brian Majestic

Third Advisor

Hillary Hamann

Fourth Advisor

Michael Keables

Keywords

Alpine, Climate, Colorado, Environment, Hydroclimate, Hydrology

Abstract

This project characterizes and examines changes to the annual hydroclimatic cycle throughout alpine regions of Colorado with a focus on trends in snowpack and snowmelt hydrology. Datasets analyzed for this research include 79 SNOTEL sites throughout Colorado (24 in the San Juan Mountains) which provide climate metrics for Water Years 1988-2018. Impacts on streamflow are evaluated in the San Juan Region through a network of 11 USGS stream gauges. Correlation matrices and linear regression methods examine the relative controls on the magnitude and timing of discharge, and trend detection using the regional Kendall test quantifies the rate of change within these systems. Results indicate that flood frequency values (regional Q100:Qm= 2.50) match snowmelt dominated regions across the Rocky Mountains. Strong correlations between annual discharge values and SWE totals (r = 0.93) also support this relationship, and variability between watersheds primarily reflects elevation constraint on the snow accumulation processes (r = -0.73). Further analysis reveals that while precipitation regulates the quantity of streamflow to a greater degree than the larger scale Upper Colorado River Basin, temperature plays a strong role in the timing of streamflow periods. Thus, observed temperature increases (+1.05℃/decade) impact the hydrology of the region through earlier snowmelt discharge (Q20 Slope = -3.7 days/decade) rather than decreased flow magnitude. Decreases in SWE max (-2.5 cm/decade) are offset by increases in Post Max SWE (+1.0 cm/decade), reflecting earlier SWE Max dates (-5 days/decade) controlled by temperature changes.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Provenance

Received from ProQuest

Rights holder

Christopher Lewis Hancock

File size

96 p.

File format

application/pdf

Language

en

Discipline

Geography, Environmental science, Climate change

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