Date of Award

January 2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Earth System Science & Policy

First Advisor

Xiaodong Zhang

Abstract

Devils Lake is an endorheic lake in the Red River of the North basin in northeastern North Dakota. During the last two decades, the lake water level has risen by nearly 10 m, causing floods that have cost more than 1 billion USD in mitigation measures. Another increase of approximately 3.0 m in the lake water level would cause spillage into the Sheyenne River. To alleviate this potentially catastrophic spillage, two artificial outlets were constructed. However, the artificial drainage of water into the Sheyenne River raises water quality concerns because the Devils Lake water contains significantly higher concentrations of dissolved solids, particularly sulfates. In this study three important concerns related to the Devils Lake flooding are being addressed: (1) How has the current wet climate cycle impacted water level and distribution of sulfate concentrations in Devils Lake? (2) Does the current outlet management increase the risk of flood and/or water quality degradation in the Sheyenne River? (4) What is the optimal outlets strategy to control Devils Lake flooding and minimize the impact on discharge and sulfate concentration in the Sheyenne River? It was found the Devils Lake water level without the operating the outlet would be 1.1 meters above its actual level in June 2018. The sulfate concentrations of Devils Lake showed a general increase from west to east, with the east end concentration being ~ 3 times greater than the west side. Since 2008, inflowing the fresh water to the lake has also decreased the Devils Lake sulfate concentration by 6%. It was found operating the outlets has increased the Sheyenne River discharge and sulfate concentration to 40 m3 s-1 and 800 mg l-1, respectively. The current outlets operation has limited the Sheyenne River discharge to less than two-year flood, however, it has violated the 750 mg l-1 North Dakota sulfate concentration standard for Stream Class I A. Based on the optimization method, an alternative management strategy was identified to control the Devils Lake water levels and preserve water quantity and quality of the Sheyenne River. Our optimization approach offered a “win-win” management strategy that maintains the efficiency of the outlets and conserves both river sulfate concentration ≤ 650 mg l-1 and discharge ≤ 26 m3 s-1. Using National Oceanic and Atmosphere Administration (NOAA) Climate Forecast System version 2 (CFSv2) data we predicted that following the alternative management will reduce the lake water levels by 0.16 m from July to October 2018.

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