Undergraduate Honors Theses

Thesis Defended

Spring 2016

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Geography

First Advisor

Dr. John Pitlick

Second Advisor

Dr. Holly Barnard

Third Advisor

Dr. Shemin Ge

Abstract

It is widely accepted that climate change will affect precipitation patterns globally. However, studies of precipitation patterns across the United States suggest that, while the frequency of heavy precipitation events is increasing in some regions, it does not appear that flood magnitudes are increasing in any systematic way. This paper examines changes in flood intensities in three regions of California for two time periods, 1950-1981 and 1982-2014.The three regions considered are the northern coast, southern coast, and the Sierra Nevada mountain region. Changes in flood intensities are evaluated using a series of statistical tests to determine if the differences in flood magnitudes between the two time periods are statistically significant based on analyses of peak flow records from unregulated rivers in each region. The results suggest that for the majority of sites (90%) there has been no significant change in mean flood intensity between the two time periods. Two rivers in the Northern region and one in the Sierra Nevada region had significant decreases in flood magnitudes. No rivers in the Southern region have experienced significant changes in flood intensity. This is likely due to compounding factors such as variations in precipitation, soil type, vegetation, and artificial drainage networks. I conclude that few flood magnitudes are changing and in no significant spatial pattern.

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