Date of Graduation

5-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Environmental Dynamics (PhD)

Degree Level

Graduate

Department

Environmental Dynamics

Advisor/Mentor

Marty Matlock

Committee Member

Greg Thoma

Second Committee Member

Linyin Cheng

Keywords

climate change, CONUS, Hydrological sciences, HUC8, runoff, seasonal shift, watershed

Abstract

The argument could be made that there is nothing more valuable on the planet than water. Our lives depend upon it. Climate change is already having an impact on the United States (US) and water stress will be one of the problems we increasingly face in coming decades. Regional research has shown that one or another part of the conterminous US (CONUS) is expected to experience an annual deficit or a surplus in runoff. Further studies have looked at changing patterns over the CONUS as a whole. Other research has focused on a particular season. This work addresses a gap in the research by analyzing water stress across the CONUS by climate region, seasonally, for each watershed. We used the widely deployed Water Supply Stress Index (WaSSI) to analyze the CONUS at the Hydrologic Unit Code eight (HUC8) scale. The aim of this work was to determine if there would be a significant change in trend of runoff from one season to the next, for each climate region. We first analyzed the projections for twenty global climate models through WaSSI, under two Intergovernmental Panel on Climate Change (IPCC) representative concentration pathways (RCP) emissions scenarios, RCP 4.5, an intermediate scenario, and RCP 8.5, a high stress scenario. The next phase of analysis focused on finding the global climate model which demonstrated the closest parallel with the historical data for the same time period. From these results, graphs were produced for every HUC8, for every season, under both RCPs. This data were then analyzed using Kendall's Tau to determine regionally significant trends. The trends for every climate region, under both RCPs, were then mapped in ArcMap to create a series of data visualizations so that the results would be easily accessible and understandable to decision-makers and lay people alike. The final phase of the research analyzed projected population changes across the CONUS in conjunction with the seasonal climate region results to underscore those cities and regions most vulnerable to water stress due to increased population. It is critical that we address the needs of our communities as water stress increases. This work will serve as a useful tool to water managers across the country.

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