Avaliação espaço-temporal das interações entre o ambiente terrestre/aquático e efeitos do barramento no alto curso do rio Ibicuí-Mirim nas características da água

Abstract

This research has the perspective of providing subsidies for a better planning for future actions that involve the management of water resources as well as help in the maintenance of artificial reservoirs, since the formation of reservoirs has influence on climate, geomorphology and ecology on a local scale , changing the fauna and flora existing in the aquatic and terrestrial environment. In this context, the hypothesis was developed to identify what modifies the dynamics of limnological variables of the drainage of a river basin with the construction of a lentic environment. This research has as main objective to analyze the influence of the reservoir Rodolfo Costa e Silva in the water system of the upper course of the Ibicuí-Mirim river. The research has as its study area the river basin of the Rodolfo Costa e Silva reservoir located on the Ibicui-Mirim river, located in the Central region of the State of Rio Grande do Sul - Brazil and covers the municipalities of Itaara and São Martinho da Serra. The reservoir is used for the water supply and sewage system of the urban area of the city of Santa Maria and is operated by CORSAN - Companhia Riograndense de Saneamento. By using limnological variables, orbital products, cartographic material, geoprocessing software and pluviometric data, the research methodology proposes to emphasize and quantify the data of terrestrial and aquatic environment through the interpretation and integrated analysis of the spatio-temporal relations that occur in these environments. In this research the limnological variables were used, as well as air temperature, water temperature, electrical conductivity, total of dissolved solids, hydrogenation potential, turbidity, total of suspended solids and potassium. In the results of this research was taken into account the analysis of the data of relief, the analysis of data of the land use, the analysis of the behavior of the limnological variables of the upstream and downstream drains of the Rodolfo Costa e Silva reservoir, the analysis of rainfall data , by considering thirty days of cumulative rainfall, preceded the field missions and the statistical analysis of the limnological data obtained from the processing of the samples of the hydrographic basin studied. Regarding land use, it was verified that in the four analyzed images, referring to the four field missions, in all of them an intense agricultural activity was verified in the session upstream of the reservoir and preservation area in the downstream section of the reservoir, with small amounts of woods-galleries in the vicinity of practically all the drainage, more intense in the downstream session and more devastated in the upstream session, where there is greater agricultural practice. In the analysis of the data of the limnological variables, it was verified that practically in all the dates of collection occurred changes in the limnological data, probably related to the change of the lotic environment to the lentic environment and again to the lotic environment, which provides different intensities of solar radiation raising the surface water temperatures and also due to the provision of new drainage in the main stream of the river basin. Thus the downstream drainage of the reservoir, a certain trend of stability is observed in all the limnological data analyzed in this research. This may be related to the fact that the region downstream of the reservoir belongs to the biological reserve Ibicui-Mirim.