Date of Award

December 2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geological Engineering

First Advisor

Taufique Mahmood

Abstract

Seasonally frozen lakes in northern, cold region plains are currently undergoing intense, precipitation-driven volumetric expansion via fill-and-spill and fill-and-merge processes. As a case study, Devils Lake, North Dakota, reached its peak volume during the past thirty years. This recent climatic episode is widely regarded as the wettest in Devils Lake’s recorded history (since 1895), with severe ramifications for flooding. Lake growth is intricately dependent on the distribution and contribution of snow water equivalent, expanding contributing areas, and upstream precipitation, including rain-on-snow (ROS). However, the intermediate mechanisms driving Devils Lake’s rapid growth remain poorly understood. This thesis deploys a physically based Cold Region Hydrological Model (CRHM Model) to analyze the net effect of hydrological processes (fill-and-spill, frozen and unfrozen infiltration, snow redistribution, melt and open-water evaporation), state variables (soil moisture and snow water equivalent), and watershed storage (depressional capacity and connectivity) on Devils Lake under recent wetting (2002-2018 Water Years).

Model results illustrate three major hydroclimatic periods at lake scale with strong model performance (NSE = 0.90; Rbias = -1.9): a contraction-growth cycle from 2002-05; laterally dominated inflow from 2006-2011; and evaporation-dominated contraction from 2012-2018, with additional impact from recently implemented anthropogenic draining. Lake growth is strongly influenced by west-to-east hydroclimatic gradients, with unevenly distributed snowpack-runoff dynamics. Understanding Devils Lake’s changing hydroclimatic response can help update near-term adaptation for floods, agriculture, and recreational fisheries, while informing managers of climatic impacts for other large, snowmelt-fed prairie lakes experiencing wetting regimes.

Available for download on Sunday, January 17, 2027

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