Hydraulic Engineering Commons^™

Hydrologic Modeling Of The Lower Chesapeake Bay Watershed Using Hecc-Hms With Implications For Future Coupled Coastal Modeling, Christopher Leonard Frost

Civil & Environmental Engineering Theses & Dissertations

This study explores the hydrological methodology for modeling a coastal watershed basin using the US Army Corps of Engineers hydrologic software, HEC-HMS with an objective of being able to create riverine boundary conditions that could be applied to a coupled compound flood model. Compound flooding is defined as high water inundation event that occurs due to the simultaneous occurrence of multiple flooding drivers. The Atlantic Seaboard and the Gulf of Mexico regions of the United States account for most of the compound events observed in the United States with a higher occurrence caused by hurricanes from July to November. In …

Combine Effects Of Heavy Storm, Sea Level Rise, And Wind-Induced Surge On Flooding In A Low-Gradient Coastal Watershed In Eastern Virginia, Rutvik Rajendrabhai Patel

Civil & Environmental Engineering Theses & Dissertations

This dissertation examines and presents mechanisms of flooding in a low-gradient coastal watershed, located in Virginia Beach, Virginia, USA. The watershed comprises the North Landing River watershed and the West Neck Creek watershed, both characterized by a low topographic gradient. The analysis relied on examining simulations generated using one-dimensional and two-dimensional HEC-RAS models. These models were developed using a 1-m digital elevation model (DEM) obtained from the U.S. Geological Survey (USGS). To calibrate and validate the models, unsteady flows resulting from historical hurricanes (e.g., Matthew, Sandy, and Isabel), southern winds, and/or rising sea levels were utilized. Some flows were caused …

Modeling Effects Of Rainwater Harvesting Systems On Water Yield Increase And Non-Beneficial Evaporation Reduction To Sustain Agriculture In A Water-Scarce Region Of China, Tennille Wade

Civil & Environmental Engineering Theses & Dissertations

The northwestern region of China, which has an arid/semiarid climate, relies heavily on agriculture to provide food for the growing population. Climate change is affecting water availability in the region, causing long periods of drought and water scarcity followed by shorter periods of heavy rainfall and excess water availability. The ridge and furrow rainwater harvesting systems (RFRWHS) are a means of solving the problem of water scarcity; the systems can replenish soil moisture, reduce non-beneficial evaporation from bare soils, and increase surface water yield. In such a region, the hydrologic cycle is dominated by soil evaporation, leading to minimal surface …

Predicting Effects Of Climate Change And Sea Level Rise On Hydrologic Processes In A Mid-Atlantic Coastal Watershed, Rui Li

Civil & Environmental Engineering Theses & Dissertations

This dissertation assessed impacts of Climate Change (CC) and Sea Level Rise (SLR) on coastal hydrologic processes using the Lynnhaven River watershed as a test bed. The watershed is part of Chesapeake Bay Watershed and hydraulically connected with mid-Atlantic Ocean. Six CC scenarios were considered in terms of eight Regional Climate Models’ predictions for three Intergovernmental Panel on Climate Change (IPCC) emission assumptions, namely, B1, A1B, and A2, for two future periods, namely 2046 to 2065 and 2081 to 2099. The ensemble means of downscaling results from four methods were used to represent the future climates. On the other hand, …

Impact Of Limited Organic Carbon Addition On Nitrogen Removal In A Mainstream Anammox Moving Bed Biofilm Reactor, Johnnie Wayne Godwin

Civil & Environmental Engineering Theses & Dissertations

Excessive nitrogen compounds are a growing problem in the world and are leading to further environmental degradation. For future nitrogen pennit limits, conventional water treatment processes tend to not meet the requirements to drive these concentrations to low levels, and if they do, it can be rather costly. However, in mid 1990s a new bacterium was discovered that has allowed for nitrogen removal to occur at a considerably reduced cost. The use of anaerobic ammonia oxidizing bacteria (anammox or AMX) is well established in sidestream deammonification (partial nitritation and anammox). However, as of late there has been discussion of applying …

Adsorption-Style Activated-Sludge: Is It A Practical Treatment Process In North America?, Jon Dearmond

Civil & Environmental Engineering Theses & Dissertations

Adsorption/Bio-Oxidation (A/B) processes occupy a small footprint and can be exceptionally energy efficient to the point of being energy positive in optimum conditions. They have the ability to handle industrially influenced municipal wastewater with high pH and BOD swings. The A/B plant configuration also appears to be a great platform for shortcut nitrogen removal processes because of the controlled carbon diversion capabilities of the adsorption stage (A-stage). In Europe, these plants have been successfully implemented at full scale since the early 1980s. However, in the U.S. there is a false conventional wisdom that plants operating at very low SRT's will …

Operation And Modification Of A B-Stage For Efficient Nitrogen Removal In An A/B Process Pilot Study, Ryder Bunce

Civil & Environmental Engineering Theses & Dissertations

Hampton Roads Sanitation District's Chesapeake-Elizabeth Wastewater Treatment Plant is a High-Rate Activated Sludge (HRAS) plant with no primary clarifiers. The plant operates at an SRT of 1.5 - 2 days and does not perform biological nitrogen removal (BNR). By 2021 HRSD anticipates the plant will be included in a bubble permit, resulting in a total nitrogen (TN) effluent target of approximately 5-8 mg/L. Converting the plant to a conventional BNR process would require a significant increase in reactor volume. Capital costs for the upgrade are estimated at 125 -150 million dollars, with a dramatic increase in operating costs as well. …

Optimization Of Demon® Sidestream Treatment And Potential For Anammox Mainstream Bioaugmentation, Andrea Lauren Nifong

Civil & Environmental Engineering Theses & Dissertations

Anaerobically digested sludge dewatering liquors (e.g. centrate) can represent 15-25% of the total kjeldahl nitrogen (TKN) load on a typical municipal waste water treatment plant (WWTP). Sidestream nitrogen removal has been demonstrated to be an effective tool for improving nitrogen removal performance and reliability with a savings in aeration energy, chemicals (supplemental alkalinity and carbon), and sludge production.

Deammonification, partial nitritation by ammonia oxidizing bacteria (AOB) combined with anaerobic ammonium oxidation (AMX or anammox), provides near complete nitrogen removal with a 65% reduction in energy and 100% reduction in supplemental carbon and alkalinity requirements as compared to traditional nitrification-denitrification. The …

Massive Spatiotemporal Watershed Hydrological Storm Event Response Model (Mhserm) With Time-Lapsed Nexrad Radar Feed, Changqing Song

Civil & Environmental Engineering Theses & Dissertations

Correctly and efficiently estimating hydrological responses corresponding to a specific storm event at the streams in a watershed is the main goal of any sound water resource management strategy. Methods for calculating a stream flow hydrograph at the selected streams typically require a great deal of spatial and temporal watershed data such as geomorphological data, soil survey, landcover, precipitation data, and stream network information to name a few. However, extracting and preprocessing such data for estimation and analysis is a hugely time-consuming task, especially for a watershed with hundreds of streams and lakes and complicated landcover and soil characteristics. To …

Source Identification Of Ammonia Inputs To The Wastewater Treatment Holding Pond At International Paper Franklin Mill, Melissa Riddick Wolford

Civil & Environmental Engineering Theses & Dissertations

While nitrogen is an essential nutrient in aquatic systems, elevated levels of nitrogen can be fatal to many aquatic organisms including fish and other organisms that are in the river. Elevated levels of ammonia have been recently (2001-2002) detected in the water released from a wastewater treatment system holding pond at International Paper Franklin, Virginia and are a concern for the receiving system. The elevated ammonia concentrations observed in previous years were not observed in 2003, due likely to increased precipitation and the occurrence of a major hurricane (Hurricane Isabel) during the sampling period that may have influenced the observations. …

Unsteady Flow Model For An Irrigation Canal Network, Talaat Taher El Gamel

Civil & Environmental Engineering Theses & Dissertations

A mathematical model is developed to route unsteady flow through an irrigation canal network. The model is designed to handle branches, lateral inflow and outflow, sluice gates, and various boundary conditions. The model is developed for use on a personal computer. A specific irrigation canal network in Egypt is used as a case study to verify the model, and the results are presented. Full documentation is included in the appendix.

A Buffered Advection/Dispersion Lake Water Quality Transport Framework For Modeling Lake Gaston Pipeline Intake Water Withdrawal, Lloyd Ashton Gatling

Civil & Environmental Engineering Theses & Dissertations

Water quality response to reservoir water withdrawal is investigated in Pea Hill Arm of Lake Gaston, a non-tidal reservoir tributary, where the point of water withdrawal is in an upstream tributary and influences the direction of tributary flow causing longitudinal velocity null flow conditions to occur. The study also focuses on control of withdrawal rate and timing to optimize both quality of water remaining in the tributary and quantity of water that can be safely withdrawn.

Research was conducted assuming steady state conditions and later under spatial and temporal variability experienced in the reservoir with main lake pool elevation fluctuations …

Development Of Baseline Water Quality Stormwater Detention Pond Model For Chesapeake Bay Catchments, William J. Musico

Civil & Environmental Engineering Theses & Dissertations

A stormwater detention pond model, EEMD (Environmentally Economic Management Design), was developed using VisualBasic to facilitate the design of extended detention basins. A detention basin is a design such that a site's stormwater runoff would meet certain environmental impact requirements. To ensure these environmental requirements are meet the Commonwealth of Virginia subscribes to the procedures outlined by the Chesapeake Bay Local Assistance Department (CBLAD).

The purpose of the Chesapeake Bay Local Assistance Department (CBLAD) Calculation Procedures is to ensure that the development of constructed areas do not further exacerbate current problems of stormwater-induced eutrophication and downstream flooding. The methodology is …

Comprehensive Conjunctive-Use Management Of Connected Surface Water Groundwater Systems Using Stochastic Inputs And Uncertainties, Seshadri Suryanarayana

Civil & Environmental Engineering Theses & Dissertations

A comprehensive conjunctive-use management model is developed. The dynamics of flow and solute transport processes in connected surface water groundwater systems are integrated by a dual programming management model. The governing aquifer flow parameters and streamflows are treated as stochastic random processes. Multiple realizations of the random field are generated and are explicitly incorporated in a non-linear optimization model along with other system, environmental, and management constraints. To facilitate management of large aquifer systems, a linked simulation-optimization approach is used. The simulation program generates the response matrices for flow and transport processes. The management model then determines optimal well discharges …

A Two-Dimensional Model For Watershed Runoff And Pollutant Transport, Laura Jean Howard

Civil & Environmental Engineering Theses & Dissertations

A two-dimensional mathematical model is developed for the quantitative and qualitative analysis of watershed runoff for a given rainfall event. The runoff is routed through a receiving channel. The model is designed for use on a personal computer. Full documentation is included in the Appendix. The model is capable of accommodating downstream boundary conditions, temporally varied effective rainfall conditions, and spatially varied watershed conditions. Output takes the form of flow depths, discharges, and concentrations. The model was tested for quantity and quality using existing experimental data, and the results are presented herein.

A Quantitative Approach To Simulation And Analysis Of Storm Water Systems, John Nathan Paine

Civil & Environmental Engineering Theses & Dissertations

A generalized package of hydrologic and hydraulic models and programs is developed for the quantitative analysis of watersheds and drainage networks. The package is microcomputer based and is available to interested parties. Full documentation is included in the Appendix. The approach applies a lengthy historical rainfall record to the system in continuous simulation. One of the most powerful operational hydraulic routing models available is adopted into the package. Output takes the form of statistical predictions of flood stages, discharges, storage requirements, and rainfall analyses for various return-periods. Computer runs are completely summarized. The package was applied to a 969-acre watershed …

Removing Fluoride From Drinking Water By Organic Polymers, Eleni Davou Achilleos

Civil & Environmental Engineering Theses & Dissertations

Fluoride is a substance that can provide beneficial or detrimental effects depending on the total amount ingested. Naturally occurring high fluoride concentrations exist in many drinking water supplies. The fluoride removal methods developed in the past have been found to be either impractical and/or not cost effective.

The purpose of this study was to determine whether organic polymers can effectively remove fluoride. The water used in this study contained naturally occurring fluoride concentrations between 4.5 to 5.5 mg/1 and it was collected from the City of Franklin, Virginia, water supply system. Laboratory jar test procedures, which simulated a conventional water …

Selecting Non-Point Source Pollution Treatment Practices Using Linear Optimization, John Gardy Garland Iii

Civil & Environmental Engineering Theses & Dissertations

This paper provides a case study application of a linear optimization program as a water quality management tool. The optimization program seeks to minimize the cost of nonpoint source pollution control by selecting the best combination of pollution control management practices for Hampton, Virginia. The management practice options are grass swale roadways, porous pavers, ponds, detention basins and fertilizer management education. Management practice selection is limited by constraints on land-use and water quality. Pollutants evaluated are total nitrogen, total phosphorus, suspended solids, fecal coliforms and biochemical oxygen demand (five-day). The value in the water quality constraints for pollution loading on …

Groundwater Management By Linear Programming, Seungho Song

Civil & Environmental Engineering Theses & Dissertations

Three hydraulic optimization models are developed. These models combine the finite difference equations of two-dimensional groundwater flow in composite aquifers with various linear programming techniques. The hydraulic submodel employed in these hydraulic optimization models is so versatile that it accounts for time varying pumpage, leaky artesian conditions, a variety of boundary conditions, induced infiltrations from streams or rivers, and conversion from artesian to water table conditions. The objective of submodel 1 is to maximize the total hydraulic head from pumping wells at the end of a study period. The objective of submodel 2 is the same as submodel 1, but …

Selection Of Sludge Conditioning Chemicals And Filter Media For Vacuum Filter Dewatering Of Sludge At The Atlantic Wastewater Treatment Plant, Douglas W. Fredericks

Civil & Environmental Engineering Theses & Dissertations

A literature review was conducted to determine the types of vacuum filter systems available for sludge dewatering, the characteristics of wastewater sludge which are important to dewatering, and the methods of sludge conditioning for vacuum filtration which are available. Capillary suction time and Buchner funnel tests were performed to determine the dewatering characteristics of sludge conditioned with ferric chloride and lime, polymer, polymer and lime, and polymer and incinerator ash. Filter leaf tests were performed to determine filter cake release characteristics of various conditioned sludge and the performance characteristics of several filter media. It was determined that ferric chloride and …

Treatment Process Optimization At The Lee Hall Water Treatment Plant Newport News, Virginia, Marcy Granum Garnett

Civil & Environmental Engineering Theses & Dissertations

Various methods can be used in operating a water treatment plant. It is desirable to produce good quality water as efficiently and economically as possible. This study evaluates each phase of operation at the Newport News (Lee Hall} water treatment plant for overall efficiency.

This study begins by giving a detailed description of the Lee Hall water treatment plant. The description includes sources of water, a description of each treatment process, a plan view of the treatment plant, and a flow diagram of the treatment plant.

Based on the raw water data, flow rates, and the treatment plant characteristics, the …

Evaluating The Effects Of Alum With Polyelectrolyte Coagulant Aids In Treatment Of Low Turbidity Waters, Kenneth John Stockwell

Civil & Environmental Engineering Theses & Dissertations

Potable water sources usually require treatment for removal of suspended organic and inorganic particles. Conventional treatment processes incorporate chemical coagulants for removal of these suspended particles. Alum is a widely used coagulant that can provide adequate removals of turbidity. However, high alum dosages are required for treatment of low turbidity waters producing a voluminous sludge that is difficult to dewater.

Recent Federal regulations have limited disposal options for chemical sludges. This has prompted a reevaluation of coagulants and their dosages with the goal of reducing the amount of sludge produced and improving the sludge handling characteristics necessary for ultimate disposal. …

Transient Two Dimensional Ground-Water Flow: A Comparison Of Computed And Analytical Results, Robert Jan Fennema

Civil & Environmental Engineering Theses & Dissertations

The exact analytical solution of the transient-flow equation is compared with the finite difference solution. The finite difference program, written by the author, uses an iterative alternating direction implicit procedure to solve the linearized partial differential equation. A second order accurate central difference method is employed to solve the equation in two dimensions.

Variable cell spacing to divide the physical domain, a weighting factor and a time acceleration function were used to investigate rate of convergence and accuracy of the numerical solution. The exact integral solution to the one-dimensional form of the flow equation i n radial coordinates is used …

A Model To Investigate The Influence Of Suspended Sediment On The Mass Transport Of A Pollutant In Open Channel Flow, Raymond Scott Chapman

Civil & Environmental Engineering Theses & Dissertations

The environmental impact of the transport of pollutants in open channel flow has for many years been of interest due to the continuous introduction of heavy metals, pesticides, herbicides, and other foreign substances into natural waterways. In order to fully understand this transport process, it-is necessary to examine the significance of its individual components. In the present study an explicit two-dimensional finite difference model, designed to investigate the influence of suspended sediment on the pollutant transport process, is presented. Specific attention is directed toward examining the role of suspended sediment in 1) the turbulent vertical transport mechanism in a stratified …

An Engineering Solution To Improve Water Quality In A Tidal Lagoon, Richard Warren Price

Civil & Environmental Engineering Theses & Dissertations

Rising demand for better water quality stimulated research and development of ways to improve the quality level in existing as well as proposed water systems. At present, most of the solutions focus on biological and chemical processes.

Many natural or man-made water bodies act as receivers for both point and non-point pollution sources. Employment of biological and chemical treatment has proved successful in many of these cases; however, in some cases a more natural physical solution of an engineering mode would be more desirable. A "flushing" technique using the tidal fluctuation as a driving force has been investigated and the …