Date of Award

August 2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Geological Engineering

First Advisor

Taufique H. Mahmood

Abstract

The Prairie Pothole Region (PPR) has an extremely variable climate and has pronounced impacts on wetlands as they are highly responsive to the variability in air temperature and precipitation. In recent years, the PPR has been in a wet climate condition since 1993 facilitating severe flooding in the Devils Lake Basin (DLB), North Dakota – costing the United States (U.S.) ~$1B USD. Many studies using remotely sensed imagery reported a substantial increase in the number of surface water bodies and expansion of the existing water bodies during 1988-2013. In addition to surface water area, the water storage of the potholes also substantially increased. However, few studies quantify the surface water storage and its dynamics to the recent increase in precipitation using remotely sensed data (e.g. satellite imagery and DEM) in the PPR. In this study, I assess the climate change impacts on surface water dynamics in the Devils Lake Basin (DLB) and water storage changes in the Starkweather Coulee Basin (SCB), a headwater subbasin of the terminal lake DLB. In Chapter 2, I use remotely sensed imagery, field-based streamflow observations, PRISM precipitation data and modeled open water evaporation to detect the influence of hydroclimatic drivers on surface water dynamics. A density slicing approach of the short-wave near-infrared band from Landsat imagery identified waterbodies of both lake and wetland area changes to recent wetting (1990-2017) in the DLB. My results report six phases of dry and wet conditions experienced in the DLB during 1990-2017. Substantial total surface water expansion is detected during the 2006-2011 (pre-2011) period increasing at 120 km2/year and then declining at 140 km2/year in a post-2011 (2011-2017) period. The pre-2011 changes are due to increased levels of precipitation and fill and spill processes after the 1999-2005 prairie drought. In contrast, the shrinkage of wetland areas during the post-2011 period is due to the dominance of the evaporation processes. The post-2011 open water dynamics also contradict with most climate models projecting continued wetting and subsequent wetland expansion. During the study period a hysteresis loop is detected between open water evaporation and surface water extent during the 2006-2017 period. The cold season precipitation and streamflow at multiple subbasins of the DLB are moderately correlated with open water area. 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. In Chapter 3, I accessed high resolution LiDAR DEM and monthly global surface water data (GSWD) to estimate filled storage of each pothole in the Starkweather Coulee Basin (SCB, 700 km2) – a headwater basin draining to a terminal lake (Devils Lake). My findings suggest that the SCB storage was gradually filling up during the 1993-1997 and 2005-2013 wet climatic periods. More than 90% SCB storage was filled during the 1997, 2011 and 2013 spring seasons in which the SCB experienced regional flooding. The spring (April and May) storage volume also exhibited a strong positive correlation with peak streamflow and annual streamflow volume indicating strong influence of wetland storage and fill-spill hydrology on the streamflow generation. A positive, exponential relationship between annual streamflow and permanent water storage, and an inverse, negative exponential relationship between annual streamflow and seasonal water storage in the SCB was obtained. My results from this work show: (1) drought and deluge conditions in the DLB exert a strong influence on surface water dynamics showing the lowest levels in the summer of 2021; (2) the application of remotely sensed data was successful in defining cold region watershed properties in the SCB such as water area (SWA and PWA) and filled storage and their relationship to climate and hydrology; and (3) the relationship between filled water storage (FWS) and annual streamflow volume indicates a FWS threshold for substantial streamflow generation. The methodology can be used in predicting climate and hydrology in the PPR with remote sensing applications.

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