Hydrodynamic modeling for the sustainable management of the guájaro hydrosystem, Colombia

The Guájaro reservoir is the most important water body located at the north of Colombia. It is supplied by an artificial channel (Canal del Dique) through a two floodgates system. As a result of excess nutrients and other pollution loads from the drainage basin in recent decades, the Guájaro reservoir suffers eutrophication and other pollution problems; however it still continues being exploited. For this reason, it is necessary to regulate the hydraulic structures that supply this water body, as they play an important role in managing levels, and these in turn for water supply and environmental purposes. The present work is carried out as a sustainability management alternative of the reservoir. The implementation of a two-dimensional hydrodynamic model and its calibration is achieved using time series of the free surface levels, and comparing the measured velocities and those estimated by the model for two different climatic periods, to assist the operation of the Canal del Dique-Guájaro hydrosystem. The corresponding comparisons showed a good behavior between measured and simulated data. Based on the quantitative results of the Nash-Sutcliffe reliability method, the results are considered quite satisfactory for estimating and predicting the amount of water flowing in and out of the reservoir through the channel reservoir hydrosystem

Hydrodynamic modeling for the water management of the Guájaro reservoir, Colombia

El embalse del Guájaro, en el norte de Colombia, es un sistema hídrico abastecido por un canal artificial (el canal del Dique) a través de un dispositivo de compuertas. Durante las últimas décadas, ha presentado problemas de aprovechamiento excesivo, por lo cual resulta necesario regular las estructuras hidráulicas que abastecen este cuerpo de agua, ya que desempenan ˜ un papel importante en el manejo de los niveles, los cuales, a su vez, repercuten en la oferta hídrica. Como medida de gestión para la sostenibilidad del embalse se ha desarrollado este trabajo, en que se presenta la implementación de un modelo hidrodinámico bidimensional (modelo EFDC Explorer), así como su calibración mediante la comparación de series temporales de los niveles de agua del embalse con los resultados de las velocidades medidas y las calculadas por el modelo, durante 2 períodos climáticos distintos (secas y lluvias), para contribuir con una herramienta computacional a la explotación sostenible del Hidrosistema Canal del Dique-Embalse El Guájaro. Las comparaciones realizadas mostraron un buen comportamiento y un buen ajuste entre los valores medidos y los simulados por el modelo, basados en los resultados cuantitativos de fiabilidad (Nash-Sutcliffe). Se considera que los resultados obtenidos son bastante satisfactorios y permiten estimar condiciones para la restauración, el aprovechamiento y el uso sostenible de este sistema hídricoThe reservoir of Guájaro, in northern Colombia, is a water system supplied by an artificial channel (the Canal del Dique) through a gate device. During the last decades, it has presented problems of excessive use, for which it is necessary to regulate the hydraulic structures that supply this body of water, since they play an important role in the management of the levels, which, in turn, have an impact in the water supply. As a management measure for the sustainability of the reservoir, this work has been developed, in which the implementation of a two-dimensional hydrodynamic model (EFDC Explorer model) is presented, as well as its calibration by comparing time series of the water levels of the reservoir with the results of the measured speeds and those calculated by the model, during 2 different climatic periods (dry and rainy), to contribute with a computational tool to the sustainable exploitation of the Hidrosistema Canal del Dique-El Guájaro Reservoir. The comparisons made showed a good behavior and a good fit between the measured values ​​and those simulated by the model, based on the quantitative reliability results (Nash-Sutcliffe). It is considered that the obtained results are quite satisfactory and allow to estimate conditions for the restoration, the aprovechamiento and the sustainable use of this hydric syste

Numerical modelling of the laguna verde nuclear power station thermal plume discharge to the sea

The coastal water pollution is a problem that responds to the overpopulation, natural resources exploitation and the increase of technologic development; this has led to an alteration of the physical, chemical and biological parameters of both continental and coastal waters. Among the main sources of pollution are those arising from industrial activities, this is the case of the electricity generation industry which requires large volumes of water for cooling systems. This work contributes to the knowledge of the behaviour of thermal discharges into coastal waters, and it requires solving the Navier-Stokes-Reynolds equations for shallow waters, using a numerical model formerly developed; water quality equations associated are solved too. The results obtained are satisfactory, since dispersion patterns of the thermal plume are well reproduced in accordance with the patterns measured for different climate scenarios in the zone

Hydrodynamics and water quality assessment of a coastal lagoon using environmental fluid dynamics code explorer modeling system

Ciénaga de Mallorquín is a coastal lagoon designated as a RAMSAR site due to its ecological regional and international importance. In this work, the environmental fluid dynamics code explorer modeling system was implemented to determine the spatiotemporal distribution of temperature, dissolved oxygen, chemical oxygen demand and nutrient levels, and assess the trophic status of Ciénaga de Mallorquín. The model was set up with field measurement data taken during transition period and wet season, and secondary information obtained from local authorities and environmental agencies. The results of model simulations were calibrated and verified by the root mean square error method, achieving a consistent fit for all considered variables. Average velocities were between 0.006 m/s and 0.013 m/s during the analyzed periods. The temperature was higher in the wet season than in the transition period (29°C and 31.5°C, respectively). The dissolved oxygen was similar in both periods (6.6 and 6.7 mg/L). NO3 concentrations were higher during the transition period (3.28 mg/L), with a minimum of 1.76 mg/L and a maximum of 5.09 mg/L. The lowest NO3 concentrations were found in the area influenced by the connection with the Caribbean Sea. PO4 concentrations in the wet season were lower than in the transition period (0.20 mg/L). Finally, Ciénaga de Mallorquín exhibits high productivity levels with Trophic State Index > 50 and temporal variations of mesotrophic to eutrophic. The use of Trophic State Index is useful for the management of water body eutrophication and productivity, making it particularly important in aquatic ecosystems

Hydraulic and environmental design of a constructed wetland as a treatment for shrimp aquaculture effluents

Shrimp aquaculture has grown to the extent that pressure on natural ecosystems has greatly increased. The shrimp farms effluents usually discharge their wastes, with high nutrients load, into coastal water bodies without any previous treatment. This work presents a method to design a constructed wetland for handling these effluents. Our method is based on a first order equation model and a hydrodynamic numerical model as the main component for the design process. Numerical results showed consistency with the first order theory, when pollutants concentration were reduced to values accepted by the applicable regulations

Numerical modeling of hydrodynamics in the Agua Brava lagoon, located in Nayarit, Mexico

In this paper a study of the hydrodynamics of the Agua Brava lagoon system is performed by numerical modeling. The importance of studying this lagoon system lies with aquaculture activities carried out by shrimp farms. The π-HYDRO model is used for the numerical simulations of hydrodynamics and temperature and salinity dispersion. The boundary conditions regarding ocean properties were generated with the HYCOM ocean model, whereas tides were calculated from the tidal predictions of the MAR V1.0. A hydrological study was also performed to calculate the freshwater contributions and take them into account in the numerical simulations. The scenarios analyzed are the dry and wet seasons particularly for 2013. For the case of the dry season, a slight influence of hydrological contributions to the dynamics of the lagoon is observed, where the effects of the tidal flow are predominant. For the wet scenario, the effects of both tidal and hydrological flow drive the motion within the lagoon, especially being predominant the hydrological flow due to the river discharges in the near region to the shrimp farms

Estimation of water quality parameters using landsat 8 images: application to playa Colorada Bay, Sinaloa, Mexico

In this study, empirical models were generated to estimate water quality parameters, with the objective of showing the benefits of the satellite remote sensing application in the characterization of coastal waters. The study area was Playa Colorada Bay, located in the northwest of Mexico, in the eastern part of the Gulf of California. In two seasons of the year, on-site and laboratory characterizations were carried out to determine the spatial and temporal variation of phosphates (PO4), electrical conductivity (EC), total suspended solids (TSS), turbidity, and pH of water. Samplings were selected to match Landsat 8 satellite overpass in the study area. Radiometric and atmospheric corrections were applied to the images, prior to the generation of the models. The models were generated using the linear regression technique of successive steps; water quality parameters and their logarithms were used as dependent variables, and as independent variables were used corrected reflectance values of Landsat images. The results showed that the concentration of PO4 in the analyzed water samples were higher than those recommended in the Mexican ecological criteria of water quality, to protect the aquatic life of marine water in coastal areas. In autumn, PO4 was correlated with turbidity, T, pH, and TSS. The highest correlation coefficients were presented by TSS with PO4 (r = − 0.979) and pH (r = 0.958). The water quality models that were generated had coefficients of determination (R2) in the range of 0.637 to 0.955 and show the viability of the application of Landsat 8 images in the characterization of water quality parameters in Playa Colorada Bay. Models allowed the estimation of the distribution of water quality parameters over the whole bay instead of only at the sampling stations, favoring a better understanding of their spatial distribution

Use of LANDSAT 8 images for depth and water quality assessment of el Guájaro Reservoir, Colombia

The aim of this study was to evaluate the viability of using Landsat 8 spectral images to estimate water quality parameters and depth in El Guájaro Reservoir. On February and March 2015, two samplings were carried out in the reservoir, coinciding with the Landsat 8 images. Turbidity, dissolved oxygen, electrical conductivity, pH and depth were evaluated. Through multiple regression analysis between measured water quality parameters and the reflectance of the pixels corresponding to the sampling stations, statistical models with determination coefficients between 0.6249 and 0.9300 were generated. Results indicate that from a small number of measured parameters we can generate reliable models to estimate the spatial variation of turbidity, dissolved oxygen, pH and depth, as well the temporal variation of electrical conductivity, so models generated from Landsat 8 can be used as a tool to facilitate the environmental, economic and social management of the reservoir

Effects of beach tourists on bathing water and sand quality at Puerto Velero, Colombia

Fragile coastal areas suffer from human activities. Environmental quality is one of the most important aspects in a tourist destination of sun and sand. The quality of bathing water and sand became indicators in the worldwide competition of beach destinations. We studied the water and sand quality along the beach of Puerto Velero, in northern Colombia. Water and sand beach quality were monitored during thirteen months. This allowed identifying the most significant sources of pollution along the beach, and understanding the interrelationship between tourism and the effects on the environment. Linear correlations allow assessing the association between the number of visitors and the physicochemical and microbiological parameters. The number of visitors was directly correlated with the presence of grease and oils, both in water and sand, as well as with fecal coliforms in water. A relation between the suspended solids and the presence of fecal coliforms in water and sand was observed. This statistical approach allows understanding the origin of beach sand and swimming water pollution at tourist beaches