MS, University of Cincinnati, 2024, Engineering and Applied Science: Environmental Engineering

We created the GLObal river Width from Sentinel-2 (GLOW-S), derived from Sentinel-2 imagery, to examine river width seasonality globally. GLOW-S, containing 2.1 billion observations across 797,394 river reaches for 2017-2022, represents an 8.9-fold increase in data frequency and a 2-fold increase in spatial coverage compared to previous studies, enabling the seasonality analysis of river width. Results indicate that 9.4% of rivers maintain steady widths, 30.2% exhibit sinusoidal seasonality, and 44.4% display non-sinusoidal seasonal patterns; additionally, we identified 16% of global rivers that are non-seasonal, suggesting complex environmental interactions that, along with the non-sinusoidal but seasonal rivers, require further targeted research. Larger, more regulated rivers tend to have steadier widths than smaller, free-flowing ones. The timing of peak widths varies regionally, with 31.4% occurring in April and June. This study has important implications for freshwater hydrology and ecosystems (e.g., nutrient and carbon exchange) and provides data support for future studies in this avenue and beyond.

Committee: Dongmei Feng Ph.D. (Committee Chair); Lilit Yeghiazarian-Nistor Ph.D. (Committee Member); Drew McAvoy Ph.D. (Committee Member) Subjects: Electrical Engineering

Master of Science in Engineering, Youngstown State University, 2017, Department of Civil/Environmental and Chemical Engineering

Bridges are one of the most expensive and vital infrastructures in the transportation system. However, the bridge substructure such as piers, undergoes various kinds of deterioration and damages overtime. Different kinds of repair and rehabilitation practices are needed to protect bridges from future damages. One of such common methods of pier protection is pier encasement. Pier encasement involves enclosing an existing pier with suitable materials such as PVC pipe, to increase its strength. However, the process of pier encasement increases the overall width of the pier, which might result in the rise of headwater elevation at the bridge vicinity. Moreover, this rise in headwater elevation may cause serious problems in areas located in high-risk flood zones. When the bridge and its piers are located within the defined floodway boundaries of a Federal Emergency Management Administration (FEMA) National Flood Insurance Program (NFIP) Zone AE, no rise in water surface elevation must be maintained. Therefore, this study was undertaken to find the effects of pier encasement on headwater elevation under varying pier and channel configurations. In order to study the impact of pier encasement, HEC-RAS, was used for hydraulic simulation. The hydraulic simulation was carried out for various channel configurations. The comparison was done for encased and non-encased pier conditions for the varying conditions of channel configurations, such as channel width, slope, and flow volume. The study showed the rise in headwater elevation for the channel with a smaller bottom width (20 ft, 40 ft, 60 ft, and 80 ft). The rise in headwater elevation was further increased for steeper slopes (0.7% and 1.0%) and for higher flow volume. Furthermore, winter ice jam around a bridge structure can cause serious damage to the bridge and has been one of the major problems with bridges in the northern belt of the USA. The bridge piers, which comes in contact with ice, has a significant impact on (open full item for complete abstract)

Committee: Suresh Sharma PhD (Advisor); Anwarul Islam PhD (Committee Member); Tony Vercellino PhD (Committee Member) Subjects: Civil Engineering; Climate Change; Environmental Engineering; Rehabilitation; Transportation; Water Resource Management

MS, University of Cincinnati, 2023, Engineering and Applied Science: Environmental Engineering

The construction of dams and reservoirs is essential for various purposes, such as regulating fresh water supply, generating hydropower, and controlling floods. However, these structures can significantly affect river's geomorphic processes, leading to various environmental disturbances. While avoiding dam construction is not always possible, it is crucial to document the effects of existing dams on upstream and downstream regions to understand their short term and long-term impact on river channel properties and their subsequent environment. In this study, we analyzed 21 dams constructed between 2000 and 2007 around the world using the Global Reservoir and Dam database (GRanD) and Global LOng-term river Width (GLOW) datasets. The study period was divided into two phases: pre-construction and post-construction, while excluding the dam construction period. This division allowed us to study the natural flow regime before dam construction and the altered flow regime after dam completion. To ensure data consistency and meaningful analysis, we focused on dams with a minimum of 12 years of available data during both pre- and post-construction phases. In our analysis, we examined the temporal variations in river widths before and after dam construction, considering both upstream and downstream reaches. By comparing these changes, we identified three distinct patterns of dam impacts on river widths: narrowing, stable and widening which were furthered termed as consistent or inconsistent based on their temporal nature. These findings enhance our understanding of how human-made physical structures, such as dams, can have dynamic and diverse effects on river morphology.

Committee: Dongmei Feng Ph.D. (Committee Chair); Drew McAvoy Ph.D. (Committee Member); Xi Chen Ph.D. (Committee Member) Subjects: Environmental Engineering