Adaptação e aplicação do índice de conformidade ao enquadramento(ICE) de cursos d'água

Abstract

Monitoring programs and water quality results presentation generally do not allow to evaluate the evolution of the condition of the water bodies with respect to the compliance with the standards defined by the framework. In Brazil, an index for water quality assessment is widely used, the Water Quality Index (IQA), which attributes weights for each of the ninepreviously established parameters, with quality variation curves as function of the value founds of eachs parameter. The objective of this research is to discuss the use of the methodology of the Conformity Index to the Water (ICE), developed by the Canadian Council of the Ministers of the Environmental Water Quality Index, as a tool for monitoring the waterquality situation of a water body. For that purpose, the ICE was applied in channel of Velhas river, located in Minas Gerais / Brazil. The ICE definition is based on comparison between the values of the water quality monitoring data and the quality standards established by legislation through combination of three factors: (i) F1: coverage; (Ii) F2: frequency; (Ii) F3: amplitude. Nine parameters were selected for ICE composition: (i) biochemical oxygen demand (BOD), (ii) E. coli (replaced by thermotolerant coliforms in the years prior to 2013), (iii) dissolved iron, (iv) total phosphorus, (v) total manganese, (vi) dissolved oxygen (OD), (vii) turbidity, (viii) total arsenic and (xix) total suspense solids. The monitoring of record was set between 2009 and 2015. Monitoring data of 16 stations located in the river were evaluated. The MS Excel® software was used to calculate ICE. Of record 3636 sample points were analyzed and 101 indexes were calculated. With the use of the ICE methodology, it was triedto present the importance of monitoring the river's behavior over time and of its channel in relation to the framing, allowing the identification of the points that need greater control. In general, the ICE results for in Velhas river indicate a situation of departure from the current framework, despite the trend of gradual improvement in the period analyzed. It was verifiedthat the parameters that presented the most disconformities were E. coli, total manganese, total arsenic and total phosphorus that reflect the main uses of the basin: urban agglomerates, mining and agriculture / livestock.