Segurança hídrica e abastecimento público emergencial no município de Santo Antônio de Pádua/RJ: um estudo sobre a delimitação de microbacias hidrográficas

Abstract

The objective of the present work was the delimitation of watersheds for the emergency public water supply for the municipality of Santo Antônio de Pádua. The Pomba River, a federal water body belonging to the hydrographic basin of the Paraíba do Sul River, with its source in the State of Minas Gerais, is an important source of public water supply for 16 municipalities, 13 of which are located upstream of the municipality of Paduano, in the State of Minas Gerais, and 3 in the northwestern region of the State of Rio de Janeiro. It has been found that, with the risk of dam breaks in the State of Minas Gerais, there is a need to implement a contingency plan to ensure the supply of Paduan municipalities. In this case, the delimitation of watersheds represents an important tool to establish efficient guidelines for the management of emergency public supply. In the delimitation of the watersheds, besides the reading of various literature, the Ottocoded Hydrographic Base (BHO) used by ANA in the management of water resources was used, where with the support of the free software QGIS version 3.10 A Corunã, approximately 130 watersheds were delimited. In the selection of the sub-basins, object of study, some criteria were adopted, such as: size of the spring, giving preference to areas with up to 20,000 ha, the location of the outlet, the proximity to urban settlements, that is, the representativeness of the population to be served, and last but not least, the access to the water treatment station. In view of this, five sub-basins were selected for analysis, which were Ribeirão Santo Antônio, Ribeirão do Bonito, Ribeirão dos Ourives, Ribeirão Bom Jardim and Córrego Bom Jardim. After delimiting the sub-basins, the land use was verified with data provided by GEOINEA, the morphometric parameters, climate, soil types, reliefs, etc. Using the float method, the proposal was to verify the flow rate of the sub-basins, which only the drainage area of Ribeirão Santo Antônio presented satisfactory conditions, whose observation shows a flow rate of 15.48 m³/minute, even during the dry season. The lower quantity of water in the other sub-basins is due to several factors such as, for example, rainfall rates, use and type of soil, lack of vegetation cover, in addition to the several earth dams built for local water accumulation. It is evident that the five sub-basins analyzed have emergency public supply capacity, all that is needed is to adapt them to the geographical reality of where they are located, in other words, in the districts or at the municipal seat. After the due analyses it was considered that the Ribeirão do Bonito would totally meet the criteria that guided this work. However, it would be necessary to take some structural and non-structural measures, such as the construction of a reservoir and other support structures, as a form of prevention in times of drought.