Date of Award

January 2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geological Engineering

First Advisor

Taufique H. Mahmood

Abstract

Spatiotemporal surface water extent dynamics are important factors to understand the evolution of land surface and hydrologic processes in the Prairie Pothole Region (PPR). Surface water bodies such as lakes and wetlands are highly responsive to the variability in air temperature and precipitation, making them effective indicators of long-term hydrological conditions. Increased levels of precipitation influencing subsequent fill and spill processes have facilitated the wetland behavior in the Devils Lake Basin (DLB) as well as the rising lake levels that has caused $1 billon in flood damages. To date, the impacts of recent wetting (1993-present) on surface water area dynamics are inconclusive in various Northern Great Plains (NGP) watersheds. In this study, I utilize remotely sensed satellite imagery, field-based streamflow observations, PRISM precipitation data (the combination of remote sensing and numerical model), and numerically modeled open water evaporation to detect the influence of hydroclimatic drivers on surface water extent dynamics. Here, I delineated waterbodies utilizing a density slicing approach of the short-wave infrared band (SWIR) from Landsat imagery to identify the lake and wetland area changes to recent wetting in the DLB. Our results report six phases of dry and wet conditions experienced in the DLB over the study period from 1990-2017. Substantial total surface water expansion is detected in a pre-2011 period (2006-2011) increasing at 120 km2/year and then declining at 140 km2/year in a post-2011 (2011-2017) contraction of surface water extent. The pre-2011 changes are due to increased levels of precipitation and fill and spill processes after the 1999-2005 NGP drought. In contrast, the shrinkage of wetland areas during the post-2011 period is due to the hydroclimatic dominance of evaporation. During the post-2011 period, the responses of smaller wetlands (<90,000 m2) are highly variable while the larger wetlands and lakes decline promptly due to evaporation. During the study period a hysteric loop of open water evaporation and surface water extent was also detected. With most of the global climate models predicting a continued progression of wetting conditions in the NGP, wetlands and open water area are also expected to increase. However, the findings show otherwise in the DLB where wetland areas are decreasing in the post-2011 period.

Available for download on Friday, September 03, 2021

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