Qualidade da água nas sub-bacias hidrográficas dos rios Capivari e Mortes, Minas Gerais

Abstract

The surface water resources are the main water source, for multiple uses in the southern region of Minas Gerais. Therefore, in demands such as public supply, it is essential to monitor the water quality in the water sources, aiming at water security and minimizing the resources spent with water treatment. The objective of this study was to evaluate the Trophic State Index (IET) and the Water Quality Index (IQA) in the Alto Rio Grande (GD1) and Rio Grande (GD2) Water Resources Planning and Management Units (UPGRH). Three points were sampled in the GD1 (PI -Rio Ingaí -Minduri, PII -Rio Capivari and PIII -Rio Ingaí -Luminárias) and three points in GD2 (PIV -Rio das Mortes, PV -Rio do Peixe and PVI -Ribeirão dos Tabuões) . The monitoring period was between April 2015 and February 2016, totaling eight collections. The variables evaluated were: pH, BOD, OD, Thermotolerant coliforms (TC), Turbidity, Total Solids (TS), PO43-, P, NO3-and Temperature. The EIT and the IQA were calculated according to the methodology proposed by Lamparelli (2004) and IGAM (2005). The monitored watercourses havenot yet been framed by the environmental agency, so class 2 is considered as quality reference for the evaluated stretches, aclass that is destined to the supply for human consumption, after conventional treatment, according to DN COPAM CERH 01/08. Based on the results, it was observed that the evaluated sections were classified as Hyper-nutritious, signaling excess nutrients, factor associated to diffuseand point pollution near the points of collection. In relation to the IQA, the environmental conditions indicate that all the monitoring points were classified as their results would be in the badclass, with the TC being the main responsible for the worsening of the causal indexes, being associated to the cattle raising, untreated sewage.