A nested three dimensional numerical modeling application was developed to determine the fate of pathogen indicators in Lake Pontchartrain discharged from its tributaries. To accomplish this, Estuarine, coastal and ocean model with sediment (ECOMSED) was implemented to simulate various processes that would determine the fate and transport of fecal coliform bacteria in the lake. The processes included hydrodynamics, waves, sediment transport, and the decay and transport of the fecal coliforms. Wind and tidal effects were accounted along with the freshwater inflows. All the components of the modeling application were calibrated and validated using measured data sets. Field measurements of the conventional water quality parameters and fecal coliform levels were used to calibrate and validate the pathogen indicator transport. The decay of the fecal coliforms was based on the literature and laboratory tests. The sediment transport module was calibrated based on the satellite reflectance data in the lake. The north shore near-field model indicated that the fecal coliform plume can be highly dynamic and sporadic depending on the wind and tide conditions. It also showed that the period of impact due to a storm event on the fecal coliform levels in the lake can be anywhere from 1.5 days for a typical summer event to 4 days for an extreme winter event. The model studies showed that the zone of impact of the stormwater from the river was limited to a few hundred meters from the river mouth. Finally, the modeling framework developed for the north shore was successfully applied to the south shore of Lake Pontchartrain to simulate fate and transport of fecal coliforms discharged through the urban stormwater outfalls.

Barton Springs Pool (BSP) is an important ecological and recreational resource to the City of Austin (CoA). Due to sediment accumulation, excessive algal growth, and concern for water velocities through salamander habitat, improving the flow regime of BSP was identified as an important focus for future infrastructure development in Barton Springs Pool. The CoA commissioned this project to develop and test a hydrodynamic model to provide a basis for understanding the flow dynamics of BSP, and to aid in future infrastructure developments in BSP. This phase of the project included the collection of bathymetric and velocity data, creating a hydrodynamic model of BSP that dynamically represents space-time varying 3D velocities, and testing the model using the default settings and an adjustment of the outlet coefficients. The model was run with three targeted inflow scenarios to determine both how the model responds with varying inflows, and to provide a general idea of how flow in BSP is affected by the magnitude of the inflow. The model used was the Fine Resolution Environmental Hydrodynamic Model that solves the 3D non-hydrostatic Navier-Stokes equations in a split hydrostatic/non-hydrostatic approach. The model was run using the default settings and the outputs were compared to available data. Results from these initial runs showed that further calibration is necessary. Model runs under the targeted inflow scenarios showed that as inflow increases, velocities in the upstream portion of BSP increase correspondingly, but this is not reflected in the downstream portion of BSP. / text

The Virginia Department of Environmental Quality (VADEQ) under the direction of the United States Environmental Protection Agency (USEPA) has listed the lower Appomattox River as impaired because it violates current water quality standards for fecal coliforms. To advance the analytical process by which various scenarios for improving water quality within the estuary are examined, an array of computer-based hydrodynamic and water quality models were investigated. The Dynamic Estuary Model (DYNHYD5), developed by USEPA, was used to simulate hydrodynamics within the lower Appomattox River. The Water Quality Analysis Simulation Program (WASP6.1), also developed by USEPA, was employed to perform water quality simulations of fecal coliforms. Also, a detailed literature review examined DYNHYD5 and WASP6.1 model theory, computer-based model solution techniques, and background hydrodynamic theory. DYNHYD5 sensitivity analysis showed that the model was most responsive to tidal heights (seaward boundary conditions) both upstream and downstream within the model network. Specific model parameters were varied during calibration until modeled water surface elevations converged on observed water surface elevations. A goodness-of-fit value of 0.749 was determined with linear regression analysis for model calibration. DYNHYD5 input parameter validation was performed with additional observations and a goodness-of-fit value of 0.829 was calculated. Through sensitivity analysis, WASP6.1 proved to be most responsive to coliform loading rates in the downstream direction and boundary concentrations in the upstream direction. With these results, WASP6.1 input parameters were calibrated against observed fecal coliform concentrations. A goodness-of-fit value of 0.573 was determined with linear regression analysis for model calibration. WASP6.1 input parameter validation was performed with additional observations and a goodness-of-fit value of 0.0002 was calculated. Model results suggest that hydrodynamic model calibration and validation can be improved with additional tidal height observations at the downstream seaward boundary. Similarly, water quality model calibration and validation can possibly be improved with the aid of detailed, time-variable coliform concentrations at the downstream seaward boundary. Therefore, it is recommended that a water quality sampling station and tidal stage recorder be installed at the confluence of the Appomattox and James Rivers to provide for further testing of estuary hydrodynamic and water quality models. / Master of Science

The objective of this study was to determine if numerical models commonly used for large scale applications could also be used to model flow through flood control structures in the Rigolets Pass between Lake Borgne and Lake Pontchartrain. For this purpose a small scale physical model was built. It showed that bi-stable flow can develop downstream of a constriction. Small changes in the distribution of the approaching flow significantly impacted flows downstream of the constriction. This behavior could not be properly reproduced by a small scale 2-dimensional RMA2 model of identical dimensions. A large scale RMA2 model of the Rigolets testing possible locations and geometries of flood control structures showed that this pass is very sensitive to variations in the cross sectional flow area. Even minor reductions can significantly increase headlosses and velocities. To reduce negative impacts a flood control structure should be built in a wide and shallow area of the pass.

This thesis investigates the utilization of hydrodynamic models as tools for assessing factors impacting water quality in the Ross Barnett Reservoir. The primary focus is development of a hydrodynamic model that provides transport information to subsequent application of a water quality model. Environmental Fluid Dynamics Code (EFDC) is a complex, dynamic, multi-dimensional computer model used to simulate hydrology in water bodies. The secondary focus is on data acquisition and manipulation methods for completing the hydrodynamic modeling. Monitoring was completed to create modern bathymetry of Ross Barnett Reservoir to provide accurate model cell grid representation. Temperature and dissolved oxygen profile monitoring occurred to provide data for model output comparison. The EFDC model successfully predicted lake stratification and subsequent mixing based on changes in observed meteorological conditions.

Microplastics are tiny particles that due to their small size, durability, and widespread usage have become a huge threat to the world and the environment. Aquatic environments like rivers and oceans have faced some irreparable problems such as the extinction of various marine species. Field sampling and numerical modeling are two methods that can help researchers have a better understanding of the situations to come up with the best solutions. Machine learning methods have drawn considerable attention in most engineering fields recently, which can be used in conjunction with field sampling and numerical simulation. In this study, by generating a fine mesh and using bathymetry, water level, and discharge data, a three-dimensional hydrodynamic modeling of the domain of study was conducted using TELEMAC 3D, which is a model that was used to simulate the behavior of the Fraser River in x, y, and z directions. The results were implemented to track the movements of microplastic particles in the lower part of the Fraser River. CaMPSim-3D, which is a three-dimensional Lagrangian particle tracking model was employed to track microplastic particles. This model, in addition to calculating the horizontal location of particles, computes their vertical movements too. The release locations of microplastic particles were chosen based on the locations of the wastewater treatment plants and combined sewer overflows and in the end, nine scenarios were conducted for this study. An unsupervised branch of machine learning is clustering which helps to cluster points by relying on their different properties. The OPTICS algorithm, which is a density-based clustering algorithm, was used to find the accumulation zones of microplastic particles in the lower part of the Fraser River. It should be mentioned that in all parts available measured data and information were used for validation. The results of the clustering algorithm indicated that there are eight accumulation zones in the study area and the breakwater in the upper branch of the Fraser River is an ideal place for microplastic particles to accumulate. A reasonable agreement was obtained between the model results and measured data.

Numerical modeling systems are very important tools to study tidal inlets. In order to test its capability and accuracy of solving multi-inlet system problems, this study selected two widely used numerical modeling systems: Coastal Modeling System (CMS) and Delft3D Modeling Package. The hydrodynamics modules of the two modeling systems were tested at John's Pass and Blind Pass, Florida, a dual-inlets system, based on a similar modeling scheme. Detailed bathymetric surveys and hydraulic measurements were conducted to collect water depths, tide conditions, wave and current velocities as the input data as well as verification data for the models. A comparison study was conducted by comparing computed hydrodynamic results from both models with the extensive field measurement data. Results show that both of the modeling systems yield better prediction for water levels than for current velocity. Furthermore, under the similar modeling scheme, Delft3D was able to capture the measured tidal phase lag between the ocean boundary and the coastal inlet, therefore gave better water level prediction than the CMS model. However, the CMS yielded current velocities that are closer to the measured values than the DELFT3D model. CMS has a more user-friendly Graphic User's Interface (GUI) for input data preprocessing and plotting and visualization of output data. Delft3D has faster calculation speed.

This study was conducted to ascertain the impacts of bed leveling, following ship channel dredging operations, and to also investigate the hydrodynamic flow field around box bed levelers. Laboratory experiments were conducted with bed levelers operating in the laboratory using video cameras for flow visualization. Computer software and numerical codes, called FANS, were used to validate the laboratory experiments. The study was split into two major parts: laboratory experiments and hydrodynamic modeling. The laboratory experiment was conducted to model how bed levelers interact with the ship channel bottom after hopper dredge dragheads (blades) made passes and created uneven trenches. These interactions were observed using both underwater and hand-held cameras. The hydrodynamic modeling was accomplished using GRIDGEN and PEGSUS commercial software for generating grid and input data files in the pre-processing phase, Finite-Analytic Navier-Stokes (FANS) software for simulation in the processing phase, and two commercial software (Fieldview and Tecplot) for plotting the images and graphs in the post-processing phase. An interesting phenomenon was observed in the laboratory experimental runs. The flow field showed reversed flow in front of the moving bed leveler and the trench parallel to the direction of the bed leveler. The flow in the parallel trench was observed to be in the same direction as the bed leveler movement, and it was expected that the flow would travel under the bed leveler. The bed leveler was towed at two specified constant speeds: 0.25 m/s (0.82 ft/s) and 0.5 m/s (1.64 ft/s) and at a water depth of 1.22 m (4.00 ft) Similarly, the images and plots of the hydrodynamic modeling obtained from FieldView and Tecplot software showed flow reversal, depicted by the negative velocities, within the vicinity of the trench, as the model bed leveler moved past and interacted with the fluid. The negative velocity had a magnitude close to 0.5 m/s (1.64 ft/s), which was the velocity used in running the laboratory experiments. The hydrodynamic simulation matched closely with the experimental observations, and thus, the laboratory observation was confirmed. The final results obtained from the numerical modeling helped to understand the hydrodynamic effects around the box bed leveler.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A dinÃmica dos processos relacionados à qualidade da Ãgua em reservatÃrios à funÃÃo da sua morfologia, da aÃÃo das variÃveis meteorolÃgicas e das afluÃncias e defluÃncias, em maior grau. Prever o comportamento hidrodinÃmico de reservatÃrios e o impacto causado por mudanÃas ou variabilidades na forÃante meteorolÃgica à essencial ao gerenciamento da qualidade da Ãgua e foi o objetivo principal desta tese. Para tanto foram utilizados modelos climÃticos, hidrolÃgicos, hidrodinÃmicos e de balanÃo de energia, em cascata. O comportamento da hidrodinÃmica resultante da modelagem mostrou resultados consonantes com reservatÃrios de regiÃes tropicais, representando os padrÃes diÃrios de circulaÃÃo e a formaÃÃo de estratificaÃÃes tÃrmicas no reservatÃrio modelado. As principais variaÃÃes hidrodinÃmicas sazonais puderam ser modeladas, ainda que com um alto Ãndice de incerteza. Foi realizado um monitoramento no reservatÃrio Pereira de Miranda que forneceu meios para dar inÃcio ao ciclo de modelagem e monitoramento integrado. Foi apresentada a tÃcnica de downscaling dinÃmico para a obtenÃÃo das variÃveis meteorolÃgicas de previsÃo regionalizadas, demostrando algumas possibilidades de aplicaÃÃo dos resultados dos modelos climÃticos na modelagem hidrodinÃmica de reservatÃrios, indispensÃvel na modelagem da qualidade da Ãgua. Os resultados mostraram a possibilidade de calibraÃÃo e validaÃÃo do modelo hidrodinÃmico CE-QUAL-W2 com o uso de dados de reanÃlise atmosfÃrica, aplicaÃÃo de tÃcnicas de previsÃo climÃtica na avaliaÃÃo e previsÃo dos padrÃes hidrodinÃmicos de reservatÃrios e a necessidade de um sistema de monitoramento como subsidiÃrio de informaÃÃes relevantes à modelagem, no sentido de melhorar os sistemas existentes e aumentar o nÃvel de conhecimento sobre a dinÃmica de reservatÃrios localizados no semiÃrido. / The dynamics of water quality related processes in reservoirs is a function of its morphology, the action of meteorological variables and defluÃncias inflows and, to a greater extent. Predict the hydrodynamic behavior of reservoirs and the impact of changes or variability in weather forcing is essential to the management of water quality and was the main objective of this thesis. Therefore, we used climate models, hydrological, hydrodynamic and energy balance in cascade. The behavior of the resulting hydrodynamic modeling showed results in line with tropical reservoirs, representing the daily patterns of movement and the formation of thermal stratification in modeled reservoir. The main hydrodynamic seasonal variations could be modeled, albeit with a high level of uncertainty. Monitoring on a Miranda Pereira reservoir that provided a means to begin the modeling and integrated monitoring cycle was performed. The dynamic downscaling technique to obtain the meteorological variables of regionalized forecast was presented, showing some application possibilities of the results of climate models in hydrodynamic modeling of reservoirs, essential in modeling of water quality. The results showed the possibility of calibration and validation of the hydrodynamic model CE-QUAL-W2 using atmospheric reanalysis data, application of climate prediction techniques in assessing and predicting the hydrodynamic patterns of tanks and the need for a monitoring system as Subsidiary information relevant to modeling, to improve existing systems and increase the level of knowledge about the dynamics of reservoirs located in the semiarid.

Wetlands are dynamic ecosystems and important sources of natural resources that provide a large array of ecosystem services. Unfortunately, most wetlands are threatened by human and natural stressors, such as damming, irrigation, water abstraction, climate change and variability that compromise the sustainability of the whole system. The Inner Niger Delta (IND), Mali, West Africa, is one of the biggest floodplains in the world, has a vast natural resource that attracts many people to live in and around the delta. The IND is considered a hub of human activities that include agriculture, fishing, transport, and tourism and plays an important role in promoting sustainable development for food security, water management, and the environment. As for most wetlands in the world, the very existence of the IND is at stake with the ever-increasing number of dams and irrigation schemes that are built to feed the growing population in the region. Given the fragility of the system and the multiplicity of water uses in the IND, the current knowledge of the flood dynamics and its relation to ecosystem services and the productivity of economic activity is insufficient. There is no operational hydrodynamic model of the IND, and the Malian authorities rely on simplified models and empirical relations for water resources management in the area. This thesis contributes to a better water resources management of the IND by a) developing the first 2D hydrodynamic model based on a triangular adaptative mesh of the IND that performs well despite the poor quality of available topographic/bathymetric data b) developing an innovative way of accounting for the strong hysteresis phenomenon in the IND in the hydrodynamic modeling that allowed a better reproduction of the hydraulic connectivity between important lakes and the main river and c) developing the first non-stationary relationship between the water levels at a reference station and the flooded area in the IND. The first part of the thesis deals with the challenge of developing a hydrodynamic model using only two low-resolution satellite-derived Digital Elevation Models: the Shuttle Radar Topography Mission (SRTM), which has a 30m horizontal resolution, and the Multi-Error-Removed Improved-Terrain (MERIT). Given the low vertical accuracy of global DEMs, another DEM was derived using the waterline method, by combining water extent map from satellite images and local water level information. Channel depths were approximated using the hydraulic geometric relationship methods, while the friction coefficient was derived from the global land-use class classification (GLCC) data. The river network was extracted from the water extent map corresponding to the lowest water level. Six different hydrodynamic models were created by varying the DEM and downstream boundary conditions. Each of the models was calibrated for discharge and water levels. Bayesian Model Averaging (BMA) was finally used to combine the outputs of all six hydrodynamic models into one robust simulation. In the second part, the effect of hysteresis at the downstream boundary condition of the hydrodynamic model was examined. Existing hydrodynamic models of the IND use a static stage-discharge relationship as a downstream boundary condition during both the rise and recession of the flood, leading to potential inaccuracies in the simulation of the flood extent. This paper explores the improvement in the simulation of the flood and connectivity dynamics resulting from the use of a looped rating curve at the downstream boundary of a hydrodynamic model of the IND. The hysteresis effect is integrated into the rating curve using two methods, one based on dimensionless discharges and levels (DLRC) and the other based on the modified Jones formula (MJRC). Results show that the hysteresis effect is better represented using DLRC and that simulations using any of the modified rating curves improves the accuracy of floodplain extent simulations in the areas close to the downstream station, as well as the timing of the connectivity of the river system to one important lake in the IND. The improvement in water level simulation decreases steadily with distance from the downstream boundary of the modeled area. The third part of the thesis deals with the development of an improved relation between inundation extent and water levels in the IND. Accurate knowledge of the flooded extent considered crucial for the proper management of natural resources in the IND. Several authors have developed empirical relationships between water levels at key stations in the IND and the flooded extent in an attempt to provide simple tools to link hydraulic parameters to the performance socio-economic activities in the IND. However, simulations from a hydrodynamic model of the IND showed that the relationship between water levels and the inundation extents varies greatly from year to year, and cannot be adequately captured by static formulas. First, it is demonstrated in this paper that if the maximum water level area is known in advance, accurate relationships between water levels and inundation extents can be derived. In the second part of the paper, stepwise regression is used to develop a function that can forecast maximum water levels at Akka using observed streamflow and precipitation upstream of the Delta. The combination of the two results allows a realtime estimation of the inundated area in the IND using observed water levels, precipitation, and streamflow.