In the development of the watershed, hydrodynamic, and water quality models for Back Bay of Biloxi in Mississippi, the Better Assessment Science Integrating Point and Nonpoint Sources (BASINS 2.0) - Nonpoint Source Model (NPSM) was selected as the watershed model. The hydrodynamic and water quality models DNYHYD5 and EUTRO5 were selected as the tidally influenced bay models. The watershed model simulated nonpoint source flow and pollutant loadings for all sub-watersheds, routed flow and water quality, and accounted for all major point source discharges in the Back Bay of Biloxi watershed. Time varying output from the watershed model was applied directly to the Back Bay of Biloxi model. The Bay models, in turn simulated hydrodynamics and water quality, including water depth, velocities, and fecal coliform concentrations. Both watershed and Bay models were calibrated and verified against observed data. The calibrated/verified model was used as a planning tool to assess the water quality in the Watershed and the Bay as well as for calculating Total Maximum Daily Load (TMDL) and Waste Load Allocation (WLA).

Thesis (M.T.S.C.)--Miami University, Dept. of English, 2005. / Title from first page of PDF document. Document formatted into pages; contains [1], vi, 64, [2] p. : ill. Includes bibliographical references (p. 32).

Reusing stormwater is a sustainable approach that a lot of cities around the world, including cities in Canada, are developing to improve local and regional water resources. For this purpose, water is typically withdrawn from stormwater ponds (large urban infrastructure that retain stormwater) and used for applications that require less than pristine water quality. However, the large size of these ponds along with the heterogeneity in water quality internally, make the withdrawal location from these ponds for reusable stormwater critically important. Also due to the large sizes of these ponds, collecting data throughout the pond to determine the optimal location for withdrawal is not practical. Modelling however, can provide a more practical means of studying contaminant distribution within the pond over time in order to identify the withdrawal location, among other valuable information. In this dissertation, a modelling approach was developed that simulates fate and transport of bacteria in stormwater ponds after rainstorm events. The model was run to simulate bacteria in the Inverness stormwater pond, which is a large T-shaped pond located in southeast of the City of Calgary, Alberta, Canada. The model has two components: a hydrological component and a Computational Fluid Dynamics (CFD) component. The hydrological component calculates the stormwater runoff of the subbasins of the catchment draining into the pond. The results were compared with collected data and good agreement was observed. Then, the results were fed to the CFD component as input in order to simulate the distribution of contamination brought in by the local hydrology. The CFD component simulates the hydrodynamics of the pond 3-dimensionally. The model was run based on collected data from the pond and multiple versions of the model were developed with regard to free-surface and particulate-attached bacteria transport. In order to address a common issue with hydro-environmental models – being difficult to validate - the model was validated in two ways. First, an instrument was designed and built to measure fluid flow velocity magnitude and direction in the pond. Once calibrated, it was deployed to the pond and the flow field was measured at multiple locations for validation purposes. Second, a non-dimensional number was introduced allowing a comparison between the bacteria concentration data from collected data and that of modelling result in multiple locations of the pond. In both of the validations, good agreement with collected data was observed. A volume of Fluid model and sediment transport model were integrated into the model, which allowed consideration of free-surface effects and for modeling wider range of bacteria, respectively. The model was used to identify the optimal location for water withdrawal for reuse. The middle of the pond, where the three wings join and near the surface, was located as the optimal location due to the lowest bacteria concentration. In an attempt to improve the water quality in the optimal location, strategic tree planting on the north bank of the West wing was studied. It was shown that the trees can reduce the transport of bacteria from the most contaminated location to the withdrawal location. The model was also used to study the impact of some of the important assumptions and environmental factors, such as rain and wind, on bacteria distribution. Wind was found to play a crucial role in the bacteria distribution in the pond. / Graduate

In the development of the watershed, hydrodynamic, and water quality models for St. Louis Bay in Mississippi, the Better Assessment Science Integrating Point and Nonpoint Sources (BASINS 2.0) - Nonpoint Source Model (NPSM) was selected as the watershed model and the Environmental Fluid Dynamics Code (EFDC) which includes hydrodynamic and water quality models was selected as the Bay model. Watershed model calibration was initially accomplished utilizing historical data collected by the U.S. Geological Survey (USGS), U.S. Environmental Protection Agency (USEPA), Mississippi Department of Environmental Quality (MDEQ), and Gulf Coast Research Laboratory (GCRL). The watershed model simulated nonpoint source flow and pollutant loadings for all sub-watersheds, routed flow and water quality, and accounted for all major point source discharges in the St Louis Bay watershed. The model was executed for the period of time spanning from 1965 through 1999 in order to quantify flow and pollutant loadings under a variety of hydrologic conditions. Time varying output from the watershed model was applied directly to the St. Louis Bay model. The Bay model, in turn, simulated hydrodynamics and water quality, including water depth, velocities, salinity, temperature, and fecal coliforms. Final Bay model calibration was performed utilizing a set of site specific data acquired on St. Louis Bay during the period July 14-18, 1998. Model verification was conducted against another set of field data taken in the Bay, during April 18-27, 1999. Fecal coliform was modeled in each of the 750 segments of a three-dimensional system. Comparisons of the predicted and observed data are made qualitatively by using spatial and temporal comparisons. The response of model prediction calculations is consistent with trends of the observed data ranges. The applicability of the mathematical models is also demonstrated for the development of Total Maximum Daily Load (TMDL) for fecal coliform in the St. Louis Bay. The calibrated/verified model will be used as a planning tool to assess the water quality in the Watershed and the Bay as well as for calculating TMDL and Waste Load Allocation (WLA).

No description available.

The increase of animal agriculture coupled with excess manure production, and the reduced availability of land has led to the over application of animal manure on agricultural fields. The excessive application of manure is responsible for nutrient and bacterial pollution of downstream waterbodies. Manure application based on the crop phosphorus (P) requirements has been recommended as a viable method to reduce nutrient pollution. A plot scale study was conducted to measure the loss of nutrients and bacterial transport in runoff from cropland treated with poultry litter, dairy manure and inorganic fertilizer according to the P requirements of the crop. Three simulated rainfall events were conducted 1, 2 and 35 days after planting of corn. Highest P and N concentrations were observed in the runoff from plots treated with poultry litter, followed by dairy manure and inorganic fertilizer. The poultry litter treated plots exhibited highest concentrations of bioavailable P in the runoff, compared to all other treatments. The P from poultry litter treated plots was also mostly in the soluble form, which underscores the need to control the runoff from cropland in order to decrease the P losses from the poultry litter treated fields. The edge of the field nutrient concentrations observed in this study were high enough to cause severe to moderate eutrophication problems in downstream waterbodies unless they are diluted. In general, nutrient concentrations were lower during the second simulated event, compared with those from the first event. A significant reduction in the nutrient concentrations of runoff was observed from the second to the third simulated event for all the treatments. This reduction was attributed to the loss of nutrients by natural rainfall-runoff events during the time period between the second and the third simulated rainfall event, plant uptake of nutrients, sorption and leaching processes. The indicator bacteria analyzed in the present study were fecal Coliform (FC), Escherichia Coli (E.Coli) and Enterococcus (ENT). The bacterial concentrations reported in the runoff for the first and second simulated events were 104 to 105 times higher than the federal and state limits for primary contact recreation waters. No significant effect of treatments was observed on the bacterial concentrations in runoff. The highest concentrations were observed for FC, followed by ENT and EC in the runoff. The ratio of bacteria removed in runoff to the bacteria applied also followed the above trend. The concentrations of bacteria generally increased from the first to second simulated event; unlike the nutrients. However, the bacterial concentrations dropped significantly from second to the third simulated rainfall event to the levels lower than those designated for primary contact recreation water limits. This reduction was attributed to the washing away of bacteria by the heavy rainfall-runoff events in the period between second and third simulated rainfall events and the die-off of bacteria. The results reported from this study suggest that the manure application based on crop P requirements can also be a significant source of nutrient pollution and should be coupled with other best management practices (BMPs) also to reduce nutrient pollution. The results also suggest that the manure treated cropland can be a source for significant indicator bacterial pollution and appropriate BMPs are required to mitigate their effect. / Master of Science

This study is part of a project that was conducted by Florida International University (FIU), which designed, built, and characterized a constructed wetland (CW) wastewater treatment system in El Salvador, Central America. This study focuses on the detailed performance of a field-scale CW in the tropics, consisting of a subsurface flow wetland (SSF) and a surface flow wetland (SF). The SSF had a total area of 151.2 sq. m., filled with gravel and planted with Phragmites, Thalia, and Brachiaria, along three independent cells operating with a flow in parallel and receiving the influent domestic wastewater from a facultative lagoon and preceded the SF. The SF was a shallow open basin containing alternating regions of open water (195 sq. m. total) with submerged aquatic plants (Elodea) and regions of shallower water (605 sq. m. total) filled with emergent wetland vegetation (Typha, Thalia, and Cyperus). The design, construction, startup and operation phases of the field scale CW in that tropical setting are thus described with detail, including both SSF and SF characterization of influent and effluents. The SSF average hydraulic detention times during the wet and dry season were 2 days ± 0.9 days and 4 days ± 0.4 days, respectively; and the SF average hydraulic detention times during the wet and dry season were 20 days ± 11.1 days and 77 days ± 19.5 days, respectively. Brachiaria/Cyperus presented better results during the wet season with average BOD5 residuals of 36% ± 25%, and Thalia/Thalia during the dry season with average BOD5 residuals of 33% ± 22%. Phragmites/Typha presented better results during both seasons with average TSS residuals of 2% ± 3% (wet season), and 2% ± 2% (dry season). Residuals are also presented for COD, Oil & Grease, Total Fecal Coliform, Total Phosphorus, and Total Nitrogen. In addition, an assessment of the empirical models used in the design of the system is completed, having the EPA methodology as the preferred for BOD5 removal and three methodologies for TSS removal under tropical climate conditions. A comparison of the differences in treatment associated with each one of the selected plants and their combinations is also discussed. In summary, results strongly suggest that the CW system can effectively reduce contaminants in wastewater to levels that are comparable with the objective levels (i.e., secondary treatment levels).

Ambient and recreational surface waters worldwide experience fecal pollution due to a variety of anthropogenic sources. Fecal waste has been proven, for over a century, to harbor pathogenic microorganisms which subsequently cause a variety of disease and illness in human hosts. The benefits of utilizing fecal indicator bacteria (FIB) as a simple, inexpensive means to detect fitful human pathogens within a variety of water matrices are vast. However, no universal agreement exists in regard to which indicator is best suited for detection of fecal contamination and pathogens in environmental waters, and no single standard for bacterial indicators has been federally mandated. This study sought to explore the potential benefits of a multiple-indicator approach to water quality analysis of fresh and brackish surface waters. The distribution and fluctuation of two frequently used, EPA approved groups of FIB – fecal coliform and Enterococcus – were explored, and relationships between the two FIB groups were examined in fresh and brackish surface waters of Central and South Florida. Samples were collected over a period of 12 consecutive months, spanning April 2015 through March 2016, and analyzed using membrane filtration procedures outlined in Standard Methods 9222D and EPA method 1600. Raw and log transformed colony forming unit (CFU) data, per 100 mL, was analyzed annually and seasonally through linear regression, Spearman correlation, and exploratory data analysis techniques performed in R-Studio. The results of this study showed a moderate to strong relationship between fecal coliform and Enterococcus under both fresh and brackish conditions. The presence of a positive, linear relationship between fecal coliform and Enterococcus in both fresh and brackish water was apparent in both seasonal and annual regression analysis; upward and downward fluctuation(s) in one variable was shown to predict similar fluctuation(s) in the other year-round. However, while fecal coliform and Enterococcus showed moderate to strong correlations, causation was not implied. Low R2 values showed that the FIB groups were not dependent upon one another in any case, either annually or seasonally. The results of this study challenge previously accepted views of fecal coliform and Enterococcus effectiveness as ideal fresh and brackish water FIB, their suitability as sole indicators of fecal pollution, and their ideal usage as indicators for waters of varying salinities; results support those previously seen in studies such as Hanes and Fragala 1967, which emphasize the need for a multiple indicator approach to water quality analysis of ambient and recreational waters experiencing brackish conditions.

No description available.

To propose a methodology for the uncertainty estimation in water quality modeling as related to TMDL development, four Monte Carlo (MC) based techniques—single-phase MC, two-phase MC, Generalized Likelihood Uncertainty Estimation (GLUE), and Markov Chain Monte Carlo (MCMC) —were applied to a Hydrological Simulation Program–FORTRAN (HSPF) model developed for the Mossy Creek bacterial TMDL in Virginia. Predictive uncertainty in percent violations of instantaneous fecal coliform concentration criteria for the prediction period under two TMDL pollutant allocation scenarios was estimated. The average percent violations of the applicable water quality criteria were less than 2% for all the evaluated techniques. Single-phase MC reported greater uncertainty in percent violations than the two-phase MC for one of the allocation scenarios. With the two-phase MC, it is computationally expensive to sample the complete parameter space, and with increased simulations, the estimates of single and two-phase MC may be similar. Two-phase MC reported significantly greater effect of knowledge uncertainty than stochastic variability on uncertainty estimates. Single and two-phase MC require manual model calibration as opposed to GLUE and MCMC that provide a framework to obtain posterior or calibrated parameter distributions based on a comparison between observed and simulated data and prior parameter distributions. Uncertainty estimates using GLUE and MCMC were similar when GLUE was applied following the log-transformation of observed and simulated FC concentrations. GLUE provides flexibility in selecting any model goodness of fit criteria for calculating the likelihood function and does not make any assumption about the distribution of residuals, but this flexibility is also a controversial aspect of GLUE. MCMC has a robust formulation that utilizes a statistical likelihood function, and requires normal distribution of model errors. However, MCMC is computationally expensive to apply in a watershed modeling application compared to GLUE. Overall, GLUE is the preferred approach among all the evaluated uncertainty estimation techniques, for the application of watershed modeling as related to bacterial TMDL development. However, the application of GLUE in watershed-scale water quality modeling requires further research to evaluate the effect of different likelihood functions, and different parameter set acceptance/rejection criteria. / Ph. D.