Master of Science, The Ohio State University, 2014, Civil Engineering

Dam safety is developing into an increasingly more critical issue in the U.S. as many of our nations dams are deficient and at risk of failure. A dam failure can be a disastrous event with catastrophic consequences to the downstream area and the surrounding environment. Innundation from many dam failures have the potential for immense damage to property, the economy, the environment, and possibly fatalities. Many U.S. dams were built in first half of the 20th century and suffer from the effects of aging, deterioration, and poor engineering standards. The goals of this study are to increase situational awareness of dam owners and regulators, provide a user friendly dam safety evaluation tool, and improve the nation's overall dam safety. The methods to achieve these goals include three steps: 1) Review and compile relevant dam safety background information such as different dam materials, designs, common failure causes, and proper inspection techniques; 2) Analyze recent dam failure and incident data from the Significant Incident Reporting (SIR) database and provide recommendations for future incident reporting; 3) Create a Knowledge Based Expert System (KBES) computer program as a tool to evaluate the overall safety level of an individual existing dam.

Committee: Fabian Tan Dr. (Advisor); Frank Croft Dr. (Committee Member); Kajfez Rachel Dr. (Committee Member) Subjects: Civil Engineering; Engineering

Master of Science, University of Akron, 2017, Civil Engineering

Dams are very critical structures that are used mainly for energy production, agricultural irrigation, water storage. Seepage problems are seen in dams may require long-term and costly remediation programs by reducing the benefits of projects built for purposes such as drinking, irrigation, and energy. A widespread and potentially dangerous phenomenon related to flooding is seepage under dams, and the formation of sand boils. In this study, Koyunbaba dam located within the boundaries of Ankara/Kalecik county is examined. The study aims to calculate the amount of leakage of the alluvium lateral on the dam foundation and to calculate the optimum location, thickness, depth, and permeability of the slurry trench that can be built under the dam foundation. Groundwater Modeling System SEEP2D software which uses finite element method for calculations is used. The seepage results showed that the slurry trench significantly reduces the seepage. The thickness, depth, and permeability of the slurry trench have also been found to be essential factors in reducing leakage. It has been found that the slurry trench minimizes the leakage by up to 99%. Also, the factor of safety against piping which may occur in the downstream toe of the dam is examined. The coefficient of safety results showed that the base slurry trench should be extended to an impermeable layer or keyed the impermeable layer.

Committee: Zhe Luo Dr. (Advisor); Junliang Tao Dr. (Committee Member); Ernian Pan Dr. (Committee Member) Subjects: Civil Engineering

Master of Science in Engineering, Youngstown State University, 2012, Department of Civil/Environmental and Chemical Engineering

The nine low head dams present in the 46.1 river miles of the lower Mahoning River (from PA/OH border up to Leavittsburg dam) have been impounding the river for several decades, altering the river habitat significantly (USACE, 2006). Several studies have been done by federal and state agencies such as the United States Army Corps of Engineers (USACE) and Ohio Environmental Protection Agency (OEPA) to determine the levels of sediment contamination, fish contamination, sources of contamination and the volume and cost of sediment dredging as well as dam removal. Studies of the dams and their upstream pools were performed by a literature review, field visits, dam removal cost analysis and a HEC-RAS simulation for the lower Mahoning River water profile for pre- and post-dam removal conditions. The outputs of the study were used to rank eight of the nine low head dams using a rating system based on three major criteria - economics, environmental and other factors. Leavittsburg dam was not included in environmental criteria and two sub-criteria of other factors due to lack of sufficient information for HEC-RAS simulation. Ranking scores were allocated to each dam based on a weighted significance of the criteria with a maximum possible total of 100 points. The free flowing and impounded river length for each of the eight dam pools were predicted using the HEC-RAS outputs. The improvement in the fish population (Index of Biotic Integrity) and potential for bridge pier scouring after dam removal were also predicted from HEC-RAS output. The Struthers dam was predicted to have the highest priority for removal, followed by the Girard Liberty St. dam and Crescent St. dam, while the Warren Summit St. dam showed the lowest priority for removal.

Committee: Scott C. Martin PhD (Advisor); Hans M. Tritico PhD (Advisor); Lauren A. Schroeder PhD (Committee Member) Subjects: Environmental Engineering

Master of Arts (MA), Wright State University, 2010, International and Comparative Politics

This thesis investigates how people displaced from the construction of large dams in seek environmental justice. I studied the importance of regime type, the creation of protest groups and the formation of alliances with national, international organizations, and the media. In a comparison between protest movements against the Three Gorges Dam in China and the Sardar Sarovar Dam in India, displaced populations suffered from loss of community, livelihood, and health and were victimized by corrupt actors that supported the dams. The rapid economic development of these two countries emerged as a major point of comparison between the two. Regime type was notable in that it informed the structure of the protest movements, but was not a major determinant of the end results if the protestation. Both countries had avenues for protests. National and international NGOs and the media gave the protesters a voice in cessation of building destructive new dams. Protest movements also influenced the dissenting opinions of some politicians regarding large water infrastructure projects.

Committee: Laura Luehrmann Ph.D. (Committee Chair); Sirisha Naidu Ph.D. (Committee Member); Pramod Kantha Ph.D. (Committee Member) Subjects: Political Science

Master of Science, The Ohio State University, 2012, Environmental Science

The potential changes of dissolved oxygen concentrations caused by combined sewer overflows (CSOs) are an important consideration before and after dam removal in many urban rivers. In central Ohio, removal of a 2-m-high dam is planned in Columbus for the fourth-order Lower Olentangy River, which has several major CSOs. Two simulation models were developed, using STELLA® 9.1.4, an icon-based dynamic systems modeling software, to investigate the interactions of hydrology, water quality, CSOs, and dam removal on the Olentangy River reservoir before the Fifth Avenue Dam. The first simulation model, focusing on daily dissolved oxygen (DO), was created to predict DO changes with the pollution of CSOs before and 120 hours after dam removal. Field DO data in 2009, 2011, and 2012 were used to calibrate and validate the model. The second simulation model, a weekly water quality model, was created to simulate one-year streamflow, gross primary productivity (GPP) and DO changes before dam removal and to predict long-term water quality changes 2 years after dam removal. Field streamflow and water quality data in 2004 and 2009 were used to calibrate the model. The results from both field data analysis and model simulations suggest that large differences existed in water quality between base flow and flooding periods. The water quality of the Lower Olentangy River will be impacted immediately after dam removal. DO concentrations will continue to be significantly impacted by CSO discharges even after dam removal.

Committee: William J. Mitsch PhD (Advisor); Jay F. Martin PhD (Committee Member); Richard H. Moore PhD (Committee Member) Subjects: Environmental Science

Master of Science, The Ohio State University, 2005, Graduate School

Committee: Not Provided (Other) Subjects:

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

Master of Science, University of Toledo, 2022, Mechanical Engineering

When the COVID-19 pandemic broke out, dental clinics were asked to suspend due to an elevated risk of airborne viral transmission. Dental professionals and their assistants were thought to be at a significantly high risk due to the nature of dental procedures, which result in a high number of aerosolized particles ejected from the dental equipment and oral cavity. Several recommendations were proposed by the Centers for Disease Control and Prevention (CDC) and others to safeguard dental personnel. In this study, we quantitatively examined the efficacy of those safeguards and proposed testing additional ones. To investigate the effects of mitigation strategies on aerosol control in dental practices, we first had to accurately replicate the production of aerosols under common settings in a dental operatory, and then characterize and map particle concentration under altered standard of care practices. Numerous clinical setting scenarios, including those suggested by the CDC, were executed, and their effectiveness in reducing aerosols was assessed by characterizing the rates of aerosol production procedures. The results suggest that dry drilling generates a huge amount of particles and the use of an extraoral suction unit reduces aerosols significantly. Because the study focused on aerosolized and airborne particles, these results can be used in non-clinical situations involving the spread of airborne particles from a point source in confined spaces.

Committee: Omid Amili Dr. (Committee Co-Chair); George Choueiri Dr. (Committee Chair) Subjects: Biomedical Research; Dental Care; Dentistry; Mechanical Engineering; Particle Physics

Master of Science, The Ohio State University, 2022, Earth Sciences

Despite efforts to mitigate and reduce contamination of surface water resources, water quality remains impaired in many places worldwide, primarily due to nonpoint source pollutants including agriculture and urbanization. These both introduce excess sediment and nutrients, various types of chemicals, and more to surface waters. The Scioto River in the Upper Scioto River Basin in central Ohio was studied to assess the influence of large-scale agriculture and urbanization/suburbanization on river geochemistry. The Scioto River has its headwaters in land dominated by row-crop agriculture, then flows through the expanding metropolitan Columbus area, then again through suburbs and agricultural land south of downtown Columbus. Additionally, the river is dammed in two places, providing another means of assessing how modification of natural river systems impacts river geochemistry. The Scioto River was sampled in five locations with varying degrees of surrounding agricultural and urban land use. Samples were collected weekly at three locations from February 2021 to August 2021, then monthly through December 2021. The other two locations were sampled monthly for the entire study period. Samples were analyzed for major ions, nutrients, select trace elements, and stable water isotopes. Results revealed that concentrations of many analytes were generally highest at the most upstream location, decreased until downtown Columbus, and increased at the location furthest downstream. Because much of the study area is underlain by carbonate bedrock, correlations with Ca and/or Mg were thought to indicate a primarily geogenic source of the solute. Elements with moderate to strong positive correlations with Ca and/or Mg included Na, HCO3, Cl, SO4 F, Br, Li, U, Ni, Rb, Mo, Ba, and Sr. Additionally, many of these elements had moderate to strong negative correlations with NO3+NO2, which is primarily from agricultural inputs. Further, log C – log Q relationships of these data revealed c (open full item for complete abstract)

Committee: W. Berry Lyons (Advisor); Thomas Darrah (Committee Member); Nicholas Basta (Committee Member); Susan Welch (Committee Member) Subjects: Earth; Environmental Geology; Environmental Science; Geology; Hydrologic Sciences; Hydrology

PhD, University of Cincinnati, 2019, Arts and Sciences: History

Over the course of the nineteen and twentieth centuries, the Ohio River underwent an ecological transformation. This dissertation examines the various and competing visions for the Ohio River and how this transformation occurred through navigational and flood control engineering projects, extractive industries and pollution from expanding municipalities and industry. Its narrative begins in the early nineteenth century, when explorers and naturalists begin to explore the young United States' Ohio Territory in the west. The 981-mile long river grew as a vital artery, as it allowed for movement from the confluence of the Allegheny and Monongahela Rivers in Pittsburgh to Cairo, Illinois, where the Ohio meets the Mississippi River. Settlement grew along the river's banks, and the residents depended on the healthy river not only for transportation but as a clean water source as well. Hoping to earn profit, residents and business owners from outside the valley also sought to exploit the river's resources, such as the freshwater mussels that lived in it. Industrial interests, such as that of coal, lobbied heavily to invest in infrastructural projects as well, from the removal of snags and dredging to permanent locks and dams, over the course of the nineteenth century. These programs, especially the creation of 52 locks and dams, resulted in the removal of habitats and a series of slack pools. With the arrival of railroads, though, the Ohio River began to lose its dominance and the visions for the Ohio River changed as a result. Increasingly, residents and businesses and demanded the federal government also invest in protection from river flooding, which grew in intensity and came to a head with the thousand-year 1937 flood, and pollution abatement programs. This resulted in further engineering of the river and the Ohio Valley with the creation of flood control structures that included levees and reservoirs in the twentieth century. It also led to the creation of a regi (open full item for complete abstract)

Committee: David Stradling Ph.D. (Committee Chair); Uwe Lübken Ph.D. (Committee Member); Stephen Porter Ph.D. (Committee Member) Subjects: History

MS, Kent State University, 2019, College of Arts and Sciences / Department of Earth Sciences

Over the past decade, dam removals have become increasingly popular, as the water quality and ecological effects of impoundments are recognized and many dams near the end of their life expectancy. However, the hydrological functioning of former reservoirs has not been well documented. This study aims to develop understanding of groundwater-stream interactions and water quality in small, former reservoirs. In 2009, low head dams (~2 m) were removed from Plum Creek (Kent, Ohio) and Kelsey Creek (Cuyahoga Falls, Ohio). Plum Creek reservoir underwent channel restoration in 2011, while Kelsey Creek reservoir is unrestored and consists of a stream channel flowing through a riparian wetland. From May 2013 to August 2014, water samples were collected semi-weekly upstream and downstream of the reservoirs for measurement of pH, temperature, specific conductance, oxygen stable isotopes and chloride, nitrate, sulfate and phosphate concentrations. At Kelsey Creek, 20 piezometers and 3 wells were installed in the stream and riparian areas, for hydraulic and water quality measurements. Upstream to downstream water quality measurements revealed no evidence of water quality changes as the streams flowed through the former reservoirs. Overall, water quality was higher at Plum Creek, which has a less urbanized watershed. At Kelsey Creek, specific conductance and chloride concentrations were elevated, with the highest concentrations occurring during the late winter months. Nitrate concentrations were also high for most of the year. At Kelsey Creek, hydraulic conductivity measurements ranged from 〖~10〗^(-4) to 10^(-8) m/s and the overall geometric mean for the site was determined to be 2.35 x10-5 m/s. Sediment samples were found to have a median grain size (d50) of 1.72 mm and were poorly sorted. Groundwater flux per unit cross-sectional area revealed values between 1.32-08 m/s to 9.04-08 m/s. Potentiometric surface maps show the groundwater is moving generally in westerly (open full item for complete abstract)

Committee: Anne Jefferson (Advisor); Alison Smith (Committee Member); David Hacker (Committee Member) Subjects: Hydrologic Sciences; Hydrology; Water Resource Management

Master of Science, The Ohio State University, 2018, Environment and Natural Resources

Lowhead dams can significantly alter the geomorphology and ecology of rivers. Removal of lowhead dams is becoming increasingly common, but the ecological impacts are not fully resolved. In this study, I investigated the short-term (9-21 months after dam removal) impact of a lowhead dam removal on emergent aquatic insect communities in an urbanized portion of the Olentangy River in Columbus, Ohio (USA). Seasonality was the strongest driver of emergent insect responses, in spite of dam-removal induced changes. Measures of diversity (Simpson's Index) and community composition (% EPT) were most strongly affected by the dam removal. The interaction of time and season also emerged as important for some emergent insect responses including family evenness and richness. Water temperature, conductivity, and sediment grainsize distribution emerged as potential drivers of emergent-insect community shifts linked to dam removal. Overall, I found limited evidence to support that dam removal had a strong effect on emergent aquatic insect communities within one year. Given the limited timeframe of this study, these results should be seen as preliminary. Ongoing research in the study system will provide additional insight into the effects of dam removal on emergent aquatic insects and other riverine communities and processes.

Committee: Mazeika Sullivan Dr (Advisor); Lauren Pintor Dr (Committee Member); Rachel Gabor Dr (Committee Member) Subjects: Environmental Studies; Freshwater Ecology

MA, Kent State University, 2017, College of Arts and Sciences / Department of Geography

Cambodia's recent past includes civil war (1970-1975), genocide (1975-1979), foreign occupation (1979-1989), and armed insurgency (1979-1998). After the existence of peace and political stability and a free market system, Cambodia's economy has experienced modest economic growth, but potentially limited due to energy deficiencies. One of many measures to ensure energy supply is the proposed study of the Sambor Dam, the first and biggest mainstream dam which has ever been built along the Cambodia's Mekong River if approved. My case study of the Sambor Project focuses four villages - two upstream and two downstream. Unlike the existing scholarly studies of hydropower dams in Cambodia and most cases around the world, this research mainly studies the dam projects that have been proposed as opposed to those completed or those under construction. Three interrelated issues are addressed in this study. Firstly, it addresses the daily lives of local residents along the Sambor's Mekong River and their use of the river. To be more specific, the study provides analysis on socio-economic and cultural interaction of the four villages. Second, it examines how the Sambor Project will change their lives. Third, it provides the local residents' reactions toward the dam, if officially approved.

Committee: James Tyner Ph.D. (Advisor) Subjects: Geography

Master of Science, The Ohio State University, 2016, Environment and Natural Resources

As lowhead dams (< 7.5 m in height, run-of-river structures) are reaching the end of their functionality or structural integrity, their removal has become an increasingly popular river management and restoration practice. Geomorphic adjustment to dam removal is an emerging science; however, studies are limited that track the character of geomorphic change, particularly the short-term (intervals of only a few months) changes that occur in first few years following dam removal, which can have critical consequences on ecosystem processes occurring over these time scales. The present study reports on the geomorphic responses of the Olentangy and Scioto Rivers (Columbus, Ohio, USA) following two lowhead dam removals within an urban landscape. This study used a paired control-treatment design to quantify the geomorphic response of river channel reaches (~ 450 m long) above and below a removed lowhead dam and compare these responses to geomorphic behavior above and below existing lowhead dams over the same time period. Reaches upstream of removed dams included those which were passively-restored and actively-restored, which consisted of in-channel engineering activities. Geomorphic change was quantified through repeat bathymetric surveys using an acoustic Doppler current profiler (ADCP) and near-surface riverbed substrate sampling at several time periods (~ 2 surveys per year) within the 2-3 years following dam removal. The objective of this study was to characterize the nature of geomorphic response in terms of sediment transport processes, which was achieved through quantitative and qualitative comparison of erosion and deposition patterns, development and evolution of in-channel macrofeatures, such as the thalweg and pools, changes in reach-scale metrics of heterogeneity, and changes in riverbed substrate. Results indicate an overarching trend of summer erosional and winter depositional processes throughout the river system with some coinciding coarsening and fi (open full item for complete abstract)

Committee: Mazeika Sullivan PhD (Advisor); Kristin Jaeger PhD (Committee Member); Kaiguang Zhao PhD (Committee Member) Subjects: Environmental Science; Geomorphology; Hydrology; Water Resource Management

Master of Science, The Ohio State University, 2016, Environment and Natural Resources

Dam removal has become an increasingly popular river restoration strategy with the aim of reestablishing more natural hydrologic and sediment regimes and increasing habitat availability for aquatic organisms. However, dam-removal research is in its early stages and the ecological impacts are not fully known. For fish, the removal of lowhead dams has been shown to restore hydrologic connectivity and reestablish lotic-type species; yet the magnitudes and rates of recovery are variable across studies. Food webs represent complex trophic networks and are fundamental in understanding the organization of natural assemblages and community dynamics and in describing ecosystem processes. Therefore, incorporating a food-web approach in dam removal studies might be expected to be an important step in quantifying ecosystem responses to dam removal. Here, I investigated the consequences of two lowhead dam removals in the Olentangy and Scioto Rivers (Columbus, Ohio) for (1) fish assemblage structure and (2) fish-centered food webs 2-3 years following removal. The disturbance of dam removal had consequences for both fish assemblages and food-web structure. Upstream fish assemblages experienced a significant decline in species richness in the year following dam removal, which was accompanied by a shift in assemblage composition (ANOSIM: R = 0.714, p = 0.001). In the Olentangy River, assemblage structure shifted significantly over time (year 1-2) and included the re-colonization of benthic insectivores (ANOSIM: R = 0.136, p = 0.019). Species richness increased over time in both the Olentangy and Scioto Rivers (linear mixed models: OR – F2,16= 9.70, p = 0.002; F2,12 = 26.50, SR – p < 0.0001). Species richness returned to pre-dam removal levels in the Scioto River, but was still 58% lower than pre-dam removal levels in the Olentangy River upstream actively restored reach (i.e., where extensive channel modifications occurred) and in other experimental reaches. Shifts in assemblage (open full item for complete abstract)

Committee: Mazeika Sullivan (Advisor); Suzanne Gray (Committee Member); Kris Jaeger (Committee Member) Subjects: Aquatic Sciences; Conservation; Ecology; Freshwater Ecology

Master of Science, University of Akron, 2015, Geology

In recent years, the removal of dams from U.S. rivers has become a more frequent method of river restoration. The August 2013 removal of the 4.1-m-tall LeFever Dam in Cuyahoga Falls, Ohio was the fourth dam removed on the middle Cuyahoga River in an attempt to improve water quality. The LeFever Dam removal has also provided an excellent opportunity to study the effects of low head dam removal on the fluvial environment. Previous studies on the middle Cuyahoga River have provided a comprehensive characterization of the former LeFever dam pool and the pre-LeFever removal conditions. Previous studies have also quantified the effect of the 2005 Munroe Falls Dam removal which served as predictive tool for the LeFever Dam removal located ~ 5.5 km downstream. This study has incorporated new findings from 2011 through 2015 to quantify the rate and magnitude of the geomorphic, sedimentologic and hydraulic changes induced by the LeFever Dam removal. These new findings furthered the understanding of the long-term channel adjustments induced by the Munroe Falls Dam removal as well. The six stage channel evolution model of Doyle et al. (2003) was used as the framework for describing the first-order changes brought about by the LeFever Dam removal and the long-term changes caused by the Munroe Falls removal. However, this study has found site-specific dissimilarities in the channel evolution model that have greatly influenced channel morphology. In addition, the former LeFever Dam pool has progressed through channel evolution at a faster rate than the former Munroe Falls Dam pool because the Cuyahoga River has more slope energy near the former LeFever Dam. The presence of large woody debris and the occurrence of high discharge events have significantly increased the rate of channel erosion in the study reach. Channel coarsening has resulted from both dam removals as well as pronounced degradation of the former LeFever Dam pool sediment and prolonged channel widening upstream of t (open full item for complete abstract)

Committee: John Peck Dr. (Advisor) Subjects: Geology

MS, Kent State University, 2013, College of Arts and Sciences / Department of Earth Sciences

The Wolf Creek Dam was constructed from 1941 to 1952 and is located on the Cumberland River approximately 20 miles from Jamestown, Kentucky. Design deficiencies associated with the foundation and construction techniques of the 1930s and 1940s have resulted in uncontrolled seepage through the karst limestone foundation and piping problems at the project. Distress indicators were noticed in 1967, resulting in the installation of a seepage cutoff wall, completed in 1979. During the early 2000s instrumentation data began to indicate the dam was in distress once again. Piezometers water levels were rising, some were even flowing water. Settlement monuments showed increasing rates of settlement and upstream deformation. Crack pins installed on the crest of the dam confirmed the same settlement and deformation. Inclinometers installed in the diaphragm wall indicated that the wall had flexed and there was upstream deformation. The majority of the concerns for the dam lie in an area defined as Critical Area 1, which is located from Station 34+00 to 38+50. This research was conducted to investigate the nature of the vertical settlement and lateral displacement in the embankment occurring at the Wolf Creek Dam as well as the mechanisms responsible for these displacements. Field work in this study was conducted to collect and interpret instrumentation readings and to document any visual signs of movement. A subsurface investigation was performed to collect samples of the embankment soil for testing. Laboratory work included Atterberg limit, direct shear, and consolidation testing to determine the engineering properties of the embankment soil. The embankment monuments show as much as 5.6 inches (14.1 cm) of vertical settlement and 1.4 inches (3.7 cm) of lateral movement in the upstream direction. The diaphragm wall monuments show as much as 1.5 inches (3.9 cm) of vertical settlement and 2.0 inches (5.1 cm) of lateral movement in the upstream direction. Inclinometers show (open full item for complete abstract)

Committee: Abdul Shakoor (Advisor); Daniel Holm (Committee Member) Subjects: Geology

MS, Kent State University, 2013, College of Arts and Sciences / Department of Earth Sciences

Mountain Lake is one of only two natural lakes in the state of Virginia. The lake's origin has been attributed to either a natural solution-collapse basin, or to a landslide damming the valley of northwesterly flowing Pond Drain, or to a NW-SE trending fracture lineation. The lake is located within the breached northwest limb of a gently plunging anticline, a part of the larger Valley and Ridge physiographic province. In recent years, the lake drained almost completely, exposing the lake bottom and revealing the presence of four sinkhole-like depressions, containing piping holes at their sides and bottoms, at the northeastern and northwestern margins of the lake. This study focuses on the most likely origin of large sandstone blocks present at the northern end of the lake in an area locally referred to as "Rock City", including mapping of the block locations and analyzing the mode and extent of displacement that they have undergone. An additional objective is to investigate the piping potential of the lake-bottom sediment and its role in seepage out of the lake basin causing lake-level fluctuations. Mapping of Rock City was conducted by taking GPS readings at the corners of the rock blocks and using ArcMap Software. Investigations of the displacement mode of the rock blocks was done by comparing the measured orientations of principal discontinuity sets, forming the rock-block boundaries, with discontinuity orientations of undisturbed outcrops within the headscarp, using stereonet analysis. Grain size analysis, Atterberg limits, and a compaction-mold permeameter test were used to evaluate lake sediment's susceptibility to piping. Field observations and discontinuity data analysis indicate that Rock City is a landslide that dammed the valley of Pond Drain, consequently forming the lake. The primary mode of slope movement involves lateral spreading that is associated with extension occurring along discontinuities. The Tuscarora Sandstone rock blocks comprising R (open full item for complete abstract)

Committee: Abdul Shakoor PhD (Advisor); Daniel Holm PhD (Committee Member); Neil Wells PhD (Committee Member) Subjects: Environmental Engineering; Environmental Geology; Geology; Geomorphology; Hydrologic Sciences

Master of Science, The Ohio State University, 2004, Civil Engineering

A monitoring study was conducted on the Sandusky River, in north-central Ohio, to characterize changes in water quality and quantity before and after the removal of a low-head dam (St. John). Short-term time series of flow and turbidity were taken during the dewatering and the removal of the dam in order to determine sediment loads. High resolution spatial data, based on vertical profiles and longitudinal surveys, were collected before and after the removal to determine changes in temperature, dissolved oxygen (DO), pH, turbidity, specific conductivity, and oxidation-reduction potential (ORP) in the 18 km reservoir. Surface water samples were collected upstream and downstream of the dam before and after removal and analyzed for nitrate, ammonia, and phosphate. After dam removal, denitrification potential was studied within the former reservoir to compare the potential in newly exposed mudflats with the riverbed and the floodplain. During the breach of the dam, change in depth and turbidity was measured at a sampling station 200 m downstream. A small increase in volumetric flow was measured, however, time series data taken at the same sampling station during the removal showed a larger increase in flow. The discharge from the breach was not discernable at a gaging station 53 km downstream, however, the larger discharge from the removal was evident, though clearly attenuated. The removal also caused an increase in turbidity less than that of a bankfull storm event that occurred less than one week later, however, the duration of increased turbidity during removal was shorter than the storm event. The vertical profile of temperature and DO measured behind the dam before removal showed a decrease in temperature and DO with increasing depth from the surface. This was similar to lake stratification, not river conditions. The longitudinal surveys of temperature and DO were determined to be more variable before dam removal and more variable in the 13.7 km reservoir than in (open full item for complete abstract)

Committee: Timothy Granata (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2005, Civil Engineering

Dam removal has recently become one of the most controversial issues among the environmental society community in the United States. Release of reservoir sediment is the main uncertainty associated with this issue. This study has extensively documented the short-term changes in channel geometry, bed level profile, size distribution of substrates, and their relations with the sediment transport at the reach scale after a low-head dam removal. Before the complete removal, the structure was breached to de-water the reservoir. The suspended sediment concentration (SSC) and discharge downstream of the dam showed nearly no change during the breach. In contrast, the complete removal of the structure produced a sudden increase in downstream discharge and SSC. However, the amount of increase was insignificant compared to the annual rainfall event. The SSC within 10 months after the removal showed no significant difference with that of SSC before the removal. No bank erosion was evident at both upstream and downstream of the dam; while net deposition occurred downstream and net erosion occurred in the reservoir. Deposition and scouring were evident in the reservoir with overall decrease by 30% in bed slope. Deposition measurements showed up to a 20 cm increase in bed level downstream of the dam. Downstream bed materials size became at least 40% finer for post-removal conditions than for pre-removal conditions as a result of deposition of finer materials. High resolution Digital Elevation Models (DEMs) of the river bathymetry were generated from differential GPS surveys. The volume of deposition and erosion was computed from differencing the DEM for post-removal from the DEM for pre-removal. Compared with the observations, the transport rate estimated from the DEMs overestimated the transport rate within an order of magnitude. A 1-D hydrodynamic model, calibrated with the observations showed promising simulation results on the dynamics of dam removal and sediment transport. Th (open full item for complete abstract)

Committee: Tim Granata (Advisor) Subjects: