Semester

Spring

Date of Graduation

2021

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Lian-Shin Lin

Committee Member

Omar I. Abdul –Aziz

Committee Member

Jutla Antar

Committee Member

Bilgesu H. Ilkin

Committee Member

Michael P. Strager

Abstract

The Mid-Atlantic region (MAR) of the U.S. is subjected to a variety of stressors that affect the headwaters of the major rivers. Some of these stressors are abandoned mine drainage, agriculture, municipal point sources, urban areas, out-of-basin diversions, competing water uses, rapid population growths in the lowlands, alterations in water availability due to climate change and habitat alteration. In addition to these regional stressors, the rapid population growths and energy sources shifting have resulted in changes in land use and land cover (LULC) over the last few decades. The interactive effects of LULC and interannual/long-term climate changes have resulted in water quality changes in the region. The goal of this research is to investigate long-term changes in stream total dissolved solids (TDS) under changing LULC and climate variability in the MAR. Also, this dissertation is intended to generate understanding of how predominant LULC features, interannual climate variability, and their pollution processes interact to influence receiving water conditions.

This research consists of three complementary studies. The first study was to investigate the interactive effects of interannual climate variability and LULC on in-stream TDS trends at 27 sites in the north-central Appalachian region over a 20-year period (1990 – 2010). The second analysis was to characterize individual streams susceptibility to LULC changes and its effects on TDS changing rates at 29 monitoring sites in the MAR. The third study was to develop a modeling approach to predict the combined effects of LULC and interannual precipitation on stream TDS concentrations using data of 77 monitoring sites during 2008-2018. In these studies, traditional statistical non-parametric approaches (e.g., Mann Kendall test (MK), Theil-Sen slope estimator), principal component analysis (PCA), and advanced statistical modeling methods (structural equation modeling, SEM, and latent growth modeling, LGM) and geographical information system (GIS) techniques were used.

Results of the first study showed varying TDS trends with 16 (60%) of the sites having an increasing trend, 7 (26%) having a decreasing trend, and 4 (14%) with no statistically significant trend during a time of major LULC and climate changes. The relationships between TDS and climate revealed that 55% of the sites had a negative TDS-precipitation (TDS-P) slope; 45% had a positive (TDS-P) slope; 32% of the sites had a negative TDS-T slope and 68% had a positive TDS-temperature slope (TDS-T). Principal component analysis revealed that watersheds with an increasing TDS trend were distributed along the vectors of barren, and agriculture lands while watersheds with a decreasing TDS trend were distributed along the vectors of built-up, ice, forest, and wetland. These results exemplify how the interactions of LULC changes and interannual climate variations regulate environmental pollution processes that control TDS trend.

The second study showed that fourteen (14, 48.3%) monitoring sites had a statistically significant increasing trend; (8, 27.6%) monitoring sites had a statistically significant decreasing trend; and (7, 24.1%) sites showed no statistically significant trend. LGM modeling revealed that cultivated land, barren land, developed land, and open water significantly influenced stream’s susceptibility, which in turn regulated TDS concentrations and changing rates in the studied watersheds. These results enabled a better understanding of the role of watershed LULC in regulating susceptibility of water bodies to pollution and TDS changes in the MAR.

Use of LGM in the third study revealed that varying precipitation conditions was moderately successful in predicting TDS concentration. In addition, barren land was found to exhibit a significant positive impact on streams TDS concentrations and changing rates, while forest, wetland, cultivated land and developed land were found to have a significant negative influence. These results demonstrated that percentages of barren and cultivated lands had the major influences on streams conditions. These research outputs are expected to help water resources managers formulate and implement land use management practices to protect source waters.

Embargo Reason

Publication Pending

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