Application of the index WQI-CCME with data aggregation per monitoring campaign and per section of the river: case study—Joanes River, Brazil

Abstract

This work applied the Water Quality Index developed by the Canadian Council of Ministers of the Environment (WQI-CCME), to communicate the water quality per section of the Joanes River basin, State of Bahia, Brazil. WQI-CCME is a statistical procedure that originally requires the execution of at least four monitoring campaigns per monitoring location and the measurement of at least four parameters. This paper presents a new aggregation method to calculate the WQI-CCME because, to apply the original method in Joanes River, a huge loss of information would occur, by the fact that, the number of analyzed parameters varied between the monitoring campaigns developed by the Government Monitoring Program. This work modified the original aggregation method replacing it by a data aggregation for a single monitoring campaign, in a minimum of four monitoring locations per section of the river and a minimum of four parameters per monitoring location. Comparison between the calculation of WQI-CCME for river sections, with the index, WQI-CETESB, developed by the Brazilian Environmental Sanitation and Technology Company—CETESB, proved the applicability of the new aggregation method. The WQI-CETESB has it bases on the WQI from the National Sanitation Foundation and uses nine fixed parameters. As WQI-CCME uses the totality of the analyzed parameters without restrictions, it is more flexible, and the results seem more adequate to indicate the real river water quality. However, the WQI-CCME has a more stringent water quality scale in comparison with the WQI-CETESB, resulting in inferior water quality information. In conclusion, the WQI-CCME with a new aggregation method is adequate for communicating the water quality at a given time, per section of a river, respecting the minimum number of four analyses and four monitoring points. As a result, without a need to wait for other campaigns, it reduces the cost of a monitoring program and the period to communicate the water quality. The adequacy of the WQI-CCME was similar to the finding of others.