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This research focused on expanding the capabilities of the Water Rights Analysis Package (WRAP) for incorporating salinity considerations in assessments of water availability. A simulation modeling approach was used to address this issue and a generalized simulation model called WRAP-SALT was developed. The Brazos River Basin served as a case study to test the simulation approach adopted by the model. The simulation model adopts a generalized modeling approach applicable to any river basin system. The model tracks salinity throughout a river basin system over different periods of time for alternative scenarios of water use, reservoir system operating policies, and salt control mechanisms. The model was applied to the Brazos River Basin considering different management scenarios and the results obtained were analyzed. Reservoir reliabilities were assessed under user imposed salinity constraints. It was observed that the water supply reliabilities decreased significantly if salinity constraints were considered. Salt control dams proposed by the U.S. Army Corps of Engineers were also incorporated in the simulation of the river basin. It was observed that salinity in the main stem of the Brazos River was significantly reduced. However, no significant improvement was observed in water supply reliabilities.

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

Este trabalho contém uma revisão bibliográfica relativa à eficiência de wetlands construídas para a remoção de nitrogênio total e fósforo total. Também foram revisados diversos modelos matemáticos para a simulação desta remoção e foi efetuada uma análise crítica destes modelos. Foram empregados dados de domínio público da eficiência de remoção de nutrientes por wetlands construídas de fluxo superficial. Estes dados foram analisados procurando-se calibrar um modelo matemático para a simulação da eficiência de remoção. Observou-se, porém, que estes dados apresentam comportamento bastante complexo, sendo que, por vezes, a eficiência de remoção medida apresenta valores negativos. Partiu-se então para uma abordagem estatística destes dados, a qual poderá servir para a avaliação do risco de ocorrência de desempenho insatisfatório envolvido no dimensionamento de wetlands construídas. / This work presents a bibliographic review about the efficiency of constructed wetlands to remove total nitrogen and total phosphorus. Also many mathematics models to simulate this removal were reviewed and a critical analysis of these models was carried out. Public domain data about the removal efficiency of nutrients by constructed wetlands of surface flux were used. These data were analyzed in order to fit a mathematical model to simulate the removal efficiency. However it was found that these data present a complex behavior, including the occurrence of negative values. A statistical approach of these data was then carried out as an attempt to assess the risk of unsatisfactory performance involved in the design of constructed wetlands.

Este trabalho contém uma revisão bibliográfica relativa à eficiência de wetlands construídas para a remoção de nitrogênio total e fósforo total. Também foram revisados diversos modelos matemáticos para a simulação desta remoção e foi efetuada uma análise crítica destes modelos. Foram empregados dados de domínio público da eficiência de remoção de nutrientes por wetlands construídas de fluxo superficial. Estes dados foram analisados procurando-se calibrar um modelo matemático para a simulação da eficiência de remoção. Observou-se, porém, que estes dados apresentam comportamento bastante complexo, sendo que, por vezes, a eficiência de remoção medida apresenta valores negativos. Partiu-se então para uma abordagem estatística destes dados, a qual poderá servir para a avaliação do risco de ocorrência de desempenho insatisfatório envolvido no dimensionamento de wetlands construídas. / This work presents a bibliographic review about the efficiency of constructed wetlands to remove total nitrogen and total phosphorus. Also many mathematics models to simulate this removal were reviewed and a critical analysis of these models was carried out. Public domain data about the removal efficiency of nutrients by constructed wetlands of surface flux were used. These data were analyzed in order to fit a mathematical model to simulate the removal efficiency. However it was found that these data present a complex behavior, including the occurrence of negative values. A statistical approach of these data was then carried out as an attempt to assess the risk of unsatisfactory performance involved in the design of constructed wetlands.

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.

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No description available.

A 1-D tidal, salinity and water quality model that analyzes the general effects freshwater diversions have on the water quality of the Pontchartrain Estuary over a 17-year period is presented here. Using the modeled live algae concentrations in conjunction with the algal bloom probability model results produces an accurate prediction of algal bloom occurrences between 1990 and 2006. The model predicts that the addition of freshwater diversions into Maurepas swamp and increases to flow in the Bonnet Carré Spillway may cause more intense and frequent algal blooms to occur around the Pontchartrain Estuary. The model also predicts that high nutrient input events that occur earlier in the year (January/February) will not likely have algal blooms associated with them. When nutrient input events (even small events) occur in the late spring or early summer, algal blooms have a high probability of occurring when the salinity, temperature and light levels are sufficient.

A 1-D tidal, salinity and water quality model that analyzes the impacts of freshwater diversions with median and high flow on the water level, salinity and nutrient concentration of the Barataria Basin over a 2 period is presented here. The model predicts that the salinity of Lower Barataria decreases with the introduction of freshwater diversions. The model also predicts that nutrient concentration increases in Barataria Basin and decreases in Northern Gulf of Mexico with the introduction of diversions. The model shows the impact of freshwater diversions on water level except in the neighborhood of the diversion sites are small.