Dinâmica nictemeral das variáveis limnológicas de um reservatório da região do semiárido (Gargalheiras/RN)
The vertical distribution of environmental variables can vary throughout the day and seasonality, their knowledge can contribute to the understanding of regulatory mechanisms for aquatic ecosystems. These characteristics of reservoirs in the Brazilian semiarid region are directly affected when extre...
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| Formato: | bachelorThesis |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/37056 |
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| Resumo: | The vertical distribution of environmental variables can vary throughout the day and seasonality, their knowledge can contribute to the understanding of regulatory mechanisms for aquatic ecosystems. These characteristics of reservoirs in the Brazilian semiarid region are directly affected when extreme hydrological events occur (i.e. above average historical rains and prolonged droughts). Climate forecasts indicate an increase in the intensity and frequency of droughts in this region, leading to a reduction in the volume of reservoirs and, consequently, altering the limnological variables. In this context, the present study aimed to analyze the nictemeral dynamics (24-hour cycle) of the limnological variables of a reservoir in the semiarid during extreme rain events above the historical average and drought. Four nictemeral samples were performed, every 4 hours, in the Gargalheiras reservoir during the dry and rainy seasons, at the deepest reservoir point near the dam, measuring physical, chemical, and biological variables. A principal component analysis (ACP) was performed to analyze vertical and temporal differences. The results on a daily scale did not show significant changes in the variables analyzed in the study, pointing out that the results were mainly determined by seasonality. The results showed that the reservoir had the lowest values of stored volume (57.3% and 56.3%) in the first two samples and the other two samples obtained the highest values (83.1% and 66.5 %) due to having been realized after the spring reaches 100% of its capacity and pouring. We observed the occurrence of thermal and chemical stratification of the water column in the months that correspond to the period of drought and homogenization of the water column in the collections associated with the rainy period. The highest values of oxygen were in the months that correspond to the rainy season in the region, while the lowest values correspond to the months of the dry season. The ACP demonstrated temporal variation in the limnological parameters, separating the sample periods in before and after pouring. The period before pouring is related to the highest values of temperature, phosphorus and oxygen. While the period after pouring presented higher volumes and higher values of chlorophyll. We conclude that extreme precipitation events affect the parameters and the water quality of a reservoir that is important for public supply on a seasonal scale, but not in a daily scale. |
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