Browsing by Author "Kiaghadi, Amin"
Now showing 1 - 3 of 3
- Results Per Page
- Sort Options
Item Corrosion in Produced Water Desalination and Treatment Facilities(2017-10-12) Furrh, Jacob; Kiaghadi, AminItem Longitudinal Characterization and Modeling of Hydrodynamics and Water Quality Impacts Post Hurricanes and Severe Storms(2018-08) Kiaghadi, Amin; Rifai, Hanadi S.; Pardue, John H.; Dawson, Clint N.; Bedient, Philip B.; Hu, Yandi; Louie, Stacey M.Tropical cyclones, also known as hurricanes, can have devastating effects on coastal regions, particularly those that have become increasingly urbanized and industrialized. While much progress has been made in terms of understanding hurricane impacts on urban landscapes and infrastructure, the same is not true for impacts on natural water systems and environmental infrastructure. This dissertation focuses on this knowledge gap and develops the longitudinal data, framework and models for understanding water quality and the environmental impacts of hurricanes and severe storms using Houston as a testbed. This research encompasses data collection in Houston waterways post Hurricane Harvey in addition to historical water quality data compilation and analysis. Data on leaks and spills and potential sources of environmental pollution are compiled to develop a database that is used in water quality and geospatial inundation model development. A hurricane-specific water quality model, EFDC-SS, was developed to compare different hurricanes and storms with a focus on land inundation, spill destination in both land and water and their associated risks, and to understand the relationships between hydrographs and pollutographs following such events. Analyzing longitudinal water quality data in the Houston area revealed that the difference between pH measured before and after severe storms was significant (P-value<0.05) for rain-based events but not for surge-based events. While the dissolved concentrations of trace metals in fresh and saline water were below standards and almost non-detectable, total metals concentrations were slightly higher than their historical counterparts before Harvey. A significant and strong correlation was found among changes in metal concentrations in sediment samples before and after severe hydrologic events and corresponding changes in percentage of different grain types. The modeling results illustrated the effect of the location of a chemical release and the time at which the release occurs relative to storm surge on spill transport. The fate and transport of spills during a normal flow regime was found to be significantly different from spills during severe storms. In addition, modeling results showed the need for consideration of local runoff flows from rainfall events that typically accompany hurricanes and may coincide with storm surge.Item Sediment Dynamics and Associations with Polychlorinated Biphenyls and Dioxins in an Urban Estuary(2021-12) Govindarajan, Adithya; Rifai, Hanadi S.; Kiaghadi, Amin; Louie, Stacey M.; Rixey, William G.; Li, Hong-YiPolychlorinated biphenyls (PCBs) and dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, or “dioxins”) in the sediments of aquatic systems is a persistent global problem that poses serious health risks. This dissertation focuses on understanding the occurrence of PCBs and dioxins in the sediments of the Galveston Bay Estuary System (GBS) by first compiling flow, sediment, and PCB and dioxin data spanning two decades and then investigating the contaminant concentrations from a spatiotemporal perspective. Correlations revealed a significant impact of hurricanes and tropical storms on the sediment properties and sediment-associated PCBs and dioxins. Different spatial patterns were observed in the aftermath of the surge-based Hurricane Ike and the rain-based Hurricane Harvey. From statistical analyses, legacy sources, namely industrial sources and Superfund sites, were found to be significant contributors to PCBs and dioxins in the system. Novel distribution-based qualitative and quantitative methods of source apportionment were used to identify and quantify the sources of dioxins in the system sediment. The results indicated a global contribution from air and runoff sources across the estuarine system and over time with more localized impacts of the Superfund sites and industrial sources within the system. Statistically significant correlations were observed between source contributions from the proposed and conventional methods, demonstrating the utility of the sourcing approaches used in the study. Additionally, the proposed methods were rigorous in elucidating spatial and temporal changes in the sourcing of dioxin to the estuary, indicating their suitability for use for other contaminants and other estuarine systems. The Environmental Fluid Dynamics Code (EFDC) was used to investigate the water column and sediment dynamics within the system, including water column velocities, salinity, and suspended sediment, for both normal and rainfall conditions. The developed model helped identify locations of interest in the system with unique dynamics and possible effects on system parameters and contaminant distributions, especially during storm conditions. The Lagrangian Particle Tracking (LPT) and toxics modules were used to model the fate and transport of contaminants in the system during different hydrologic conditions. The modeling results support findings from the retrospective data analyses and provide additional insights into sediment dynamics and behavior in the estuary.