Indicadores ambientais e a gestão de bacias hidrográficas de economia agrícola: diagnóstico e reflexões sobre o caso da bacia do rio Preto, noroeste de Minas Gerais

Abstract

Among natural resources, water is characterized as an essential element for the existence of physical and social environment. With the technical and scientific development achieved in recent decades by the current society, the number of activities that demand for water has increased. These activities, many times, do not ponder their essentialityand undertake them quantitative and/or qualitatively. In agricultural catchments, the demand for water production chains a number of implications for water systems in the socio-environmental organization. In Brazil, this framework has been even more worrying, since agricultural activities are those that require more water in quantity once the demands of land for agricultural practices have increased. The compatibility between uses, demands and water availability in river basins with agricultural vocation is certainly one of the outstanding challenges of the processes of water resources management. This research illustrates these efforts because it proposes the concept of a methodologicaldiagnosis tool, whose information gathered from a Panel of Indicators support the management of agricultural watersheds. From the experience of a group of experts on issues related to the water, the proposal was developed and applied in the Preto river basin, northwest of Minas Gerais, in order to evaluate the working process of a number of indicators, besides supporting recommendations in the building of director plans and more efficient management tools in the implementation of national and state water resources policies. Out of the 88 experts invited to participate in the composition of the Panel Delphi, 39 effectively evaluated the criteria originally proposed and contributedwith their experiences. The proposed model listed out as priorities in the management of agricultural watersheds: the scaling of the agricultural economy and consumption of natural resources; forms and levels of qualitative and quantitative commitment; the identification of socio-environmental damage generated by its operation; andconstruction and implementation of mitigation measures. The implementation of the Panel in the Preto river basin, composed of 19 indicators and scaled in the classification model Driving Force-Pressure-State-Impact-Response, defined in its dimensions themain search results. The development of the areas used for agricultural activities increased during the analyzed period; the agricultural production implies a high consumption of chemicals, which means high contamination potential when concentrated on the upper Preto river, one of the main recharge areas of groundwater resources; the averagewater loss is high if the most used irrigation technique, that is, the central pivots, is considered in the basin,; some parts of the Preto river and its major runnels show physical and chemical samples of water quality parameters different from legal ones; erosive features are detected at different levels and points of the basin; there is conflict in the use of water between irrigators and hydropower sector users; despite initiatives for programs guided by principles of agro-environmental principles in the basin, it is clear that the lack of information concerning the real socio-environmental conditions of water use in agricultural activities in the basin represents gaps that may harm the decision-making processes of water resources management.