Engineering Commons^™

Predictive Modeling Of Riverine Constituent Concentrations And Loads Using Historic And Imposed Hydrologic Conditions, Mark Hagemann

Doctoral Dissertations

This research was principally concerned with the task of quantifying dissolved and suspended constituents carried in river water when direct measurements are not available. This is a question of scientific and societal relevance, and one with a long history of study and a great deal of remaining difficulty. The traditional approach to estimating these quantities, linear regression models (LMs), suffers from poor flexibility and high subsequent bias in many applications. This research applied semiparametric generalized additive models (GAMs), a more flexible class of regression models, evaluated their performance in various locations and conditions, and applied them in a proactive modeling …

Proactive Assessment Of Climate Change And Contaminant Spill Impacts On Source Water Quality, Lillian C. Jeznach

Doctoral Dissertations

Managing the water quality of surface drinking water sources has become an increasingly difficult task for water suppliers due to increased watershed urbanization and climate change. Changes in source water quality may affect public perceptions, treatment effectiveness, and ultimately costs to treat water to drinking standards. Although there are increased threats to current and future drinking water quality, current approaches to managing these threats are typically reactionary. Prior detailed modeling efforts of hypothetical events that may impair raw water quality allow for an understanding of constituent fate and transport, including potential maximum concentrations and travel times to the drinking water …

Longitudinal Tidal Dispersion Coefficient Estimation And Total Suspended Solids Transport Characterization In The James River, Beatriz Eugenia Patino

Civil & Environmental Engineering Theses & Dissertations

The longitudinal dispersion coefficient is a parameter used to evaluate the effect of cross-sectional variations on substance mixing mechanisms in estuaries influenced by tide, wind and internal density variations. Considering a two dimensional approach, this study aims at evaluating a tidal area of the lower James River at approximately 19 miles upstream from the mouth at the Chesapeake Bay, in the City of Newport News, and applies an experimental procedure based on in-situ salinity concentrations to estimate the dispersion coefficient in the area where receives a discharge from the HRSD James River Wastewater Treatment Plant, and further characterizes Total Suspended …

Influence Of Stormwater Control Measures On Watershed Hydrology And Biogeochemical Cycling, Colin D. Bell

Open Access Dissertations

Urban development replaces vegetation with impervious surfaces and natural drainage channels with pipe networks that quicken flow paths and alter hydrologic regimes. Additionally, the import of food, application of fertilizer to lawns and gardens, and heightened atmospheric deposition increases nutrient availability in urban landscapes. These excess nutrients are ultimately routed to streams through the pipe networks before it can be processed by the vegetation and microorganisms of the landscape. This combination of physical and chemical disturbances impacts stream ecosystems and degrades their ability to perform valuable services such as removal of nutrients, degradation of pollutants, and provision of recreational and …

Trend Analysis Of Water Quality In Northwest Arkansas Streams Reflects Changes In The Watershed, Zachary Paul Simpson

Graduate Theses and Dissertations

Watershed export of nutrients, sediments, and chemicals impacts receiving waters. Changes within the watershed (e.g., anthropogenic or climatic) can alter the transport of constituents in streams. Stream monitoring is crucial for understanding these effects. This study developed a potential improvement to flow-adjusting constituent concentrations in streams, an important step of analyzing monitoring data in lotic systems for trends. The method incorporates a K-fold cross-validation procedure to optimize a model explaining the relationship between the concentration and streamflow, thus providing a valuable tool to researchers in water quality. Additionally, two case studies were conducted on watersheds located in northwest Arkansas using …

Pervious Pavement Systems For High Traffic Roadways, Kevin M. Smith

Construction Management

This report highlights the benefits and detriments of pervious pavement systems through research of existing knowledge and multifaceted experiments to determine the feasibility of implementing a pervious pavement system on high traffic roadways. With over 40,000 miles of highway in the United States alone and severe water crises in states like California and growing environmental and safety concerns, the need for pervious pavements is abundantly clear. The research conducted utilizes existing knowledge on pervious pavements and applies it to the application of high traffic roadways. The experiment tests four different pervious concrete mix designs to determine compressive strength and water …

The Effect Of Green Structures On Hydrology In Urban Areas Of Akron, Ohio, Brooke Hayes, Brian Long

Williams Honors College, Honors Research Projects

Stormwater runoff is a major environmental concern in dense urban areas. Runoff in these areas contributes to flooding as well as water quality problems in the streams, lakes, and reservoirs downstream. The Cuyahoga River is the receiving waterbody for the City of Akron’s stormwater runoff. Currently, combined sewer overflow (CSO) from the city's outdated sewer system is the overriding reason for poor water quality in the Cuyahoga River.

Implementation of green infrastructure is one way to mitigate problems associated with stormwater runoff from urban areas. In this study, hydrologic modeling of the Little Cuyahoga watershed was conducted to determine how …

Water Quality Evaluation Of Tire Derived Aggregate, Richela K. Maeda

Projects

The primary objective of this study is to investigate the rate that potential water quality contaminants leach from tire-derived aggregate (TDA) as a function of time. A laboratory and field experiment is conducted to provide insight into both controlled and field settings. The laboratory portion of this study also provides a basis for evaluating the effect that alternating periods of wet and dry weather have on the potential water quality impacts of the leachate as compared to the worst-case operating condition, when TDA is constantly submerged (i.e., when placed below the permanent groundwater table). The field experiment is used to …

Long-Term Effects Of Forestry Best Management Practices On Hydrology And Water Chemistry In Three Appalchian Headwater Catchments, Kameryn I. Wright

Theses and Dissertations--Biosystems and Agricultural Engineering

In 1982, a study was initiated in the Field Branch watershed, in the University of Kentucky’s Robinson Forest, to evaluate forestry best management practice (BMP) effectiveness after intensive harvesting. The study utilized a paired watershed approach on three adjacent Field Branch subcatchments. One subcatchment was left as the control, one had BMPs implemented (including a 50-ft undisturbed buffer along the stream), and one was clear-cut to the stream’s banks without the use of BMPs (i.e. logger’s choice). Prior research has shown that logging can negatively impact watershed functions by altering stream hydrology, geomorphology, water quality, and instream habitat. Thus, the …

Evaluation Of Point Of Use Reverse Osmosis Systems For Drinking Water In Colonias, Oscar Daniel Ramirez

Open Access Theses & Dissertations

Clean drinking water is often considered a right and not a privilege, especially in first world countries. However, thousands of residents of colonias (settlements in the U.S. that lack access to basic infrastructure) struggle to obtain clean drinking water, including some in the Paso del Norte Region. Residents of colonias located in Doña Ana County, NM, and El Paso County, TX typically rely on domestic wells and hauled water, respectively, but these sources may be of inadequate quality, potentially posing a health risk due to microbiological contamination, presence of arsenic, or elevated concentration of total dissolved solids. This project brings …

Assessing Downstream Stormwater Impacts For Urban Watershed Planning, Johanna Meyer Pavlowsky

Masters Theses

"The urbanization of watersheds has caused debilitating effects to downstream aquatic ecosystems in catchments and streams. The implementation of green infrastructure (GI), such as permeable pavements and bioretention facilities, has been shown to alleviate these effects by both reducing runoff and mitigating pollutants; however, the implements are often not designed with a specific goal of water improvement. This study targets understanding a small, impaired urban watershed, and the benefits green infrastructure may have to provide environmental, social, and economic improvement to the watershed.

Portions of Rolla including much of the S&T campus drain into the impaired urban waterbody Frisco Lake, …