Document Type

Dissertation - Open Access

Award Date

2021

Degree Name

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

First Advisor

Suzette Burckhard

Keywords

Climate variability, Extremes, Floods, Great Plains, Historical records, Precipitation

Abstract

Climate variability and extreme events continue to worsen resulting in significant impacts to society and the environment. Quantifying precipitation variability, streamflow, and extreme events at local scale is crucial for local planning and management due to spatial and temporal precipitation variability which influences streamflow and thus, water resources. This study uses statistical tools to analyze 1895-2019 (125 years) of historical precipitation data to examine how long-term precipitation varies annually, seasonally, and monthly, and create climate classifications. The results show that annual precipitation is increasing linearly over time ranging from 13.2 in (1976) to 43.1 in (2010) and 5 climate classes were created. On average, precipitation is highest in June and Spring and lowest in January and Winter. The coefficient of variation (CV) shows that months and seasons with low precipitation have highly variable precipitation and vice versa. Extremes result in major damages and economic impact due to floods and droughts. To gain an in-depth knowledge, this study uses statistical methods to quantify Very Wet and Very Dry climate classifications identified from 1895-2019 precipitation data. Very Wet climate shows an annual precipitation and snowfall increase from longterm average of up to 70% and 116%, respectively, while Very Dry climate shows an annual precipitation decrease of up to 49% and snowfall decrease of up to 73%. However, the number of days with precipitation are similar for both Very Wet and Very Dry, precipitation intensity and magnitude influence total. Very Wet has highest precipitation in Summer and July while Very Dry has highest in Spring and June and both have highest snowfall in Winter. This study uses statistical methods to analyze how long-term precipitation relates to long-term flows, analyzed peak flows, and flood events. The results show higher Spring and annual correlation between precipitation and streamflow. The watershed experiences minor to major floods due to snowmelt in Winter and Spring and rainfall in Spring and Summer. The results show a highly variable and less predictable climate, and floods occur even during Very Dry climate due to extreme events and accumulation of groundwater levels from previous years or seasons. The findings show the need to incorporate climate variability at local scale in water resources management.

Number of Pages

176

Publisher

South Dakota State University

Rights

Copyright © 2021 Angelinah Ntsieng Rasoeu

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