ENVIRONMENTAL ANALYSIS OF URBANIZED RIVER BASINS IN SUBTROPICAL AREAS BASED ON THE WATER QUALITY INDICATOR (WQI), ENVIRONMENTAL LEGISLATION AND MANAGEMENT PLAN

Resumo

Water is essential for the development of human life. Since the waters have very diverse quality characteristics, we must differentiate their natural characteristics from those resulting from human action. For such purpose, a series of parameters are used to determine water quality, incorporating them into indexes, such as the Water Quality Index (WQI). Our study aims at analyzing the quality of the waters of rivers destined for capture for urban supply and rivers destined for the release of treated sewage in regions with and without monitoring stations or management plans in subtropical regions. The rivers analyzed by WQI in Brazil, in the municipality of Umuarama, were the Piava and the Pinhalzinho Segundo; and in Portugal, in the city of Porto, the rivers Ave, Leça and Douro. For the Piava, water quality was from bad to good. In the Pinhalzinho Segundo, the WQI varied from regular to bad. In Porto, both Ave and Leça presented regular water quality. For the Douro, the indexes obtained were regular to good. The values obtained by analyzed parameters were corroborated by the maximum values allowed by the legislation, for Brazil, and by the Water Institute, for Portugal; however, none of the analyzed rivers are fully within the allowed thresholds. The Piava has the Area of Environmental Protection (AEP) Management Plan, but the river still suffers from problems related to land use and occupation, which directly affect water quality and availability. The Pinhalzinho Segundo, in some parts, is grounded and the lack of AEP, together with the soil characteristics of the region, may have contributed to the water quality. The Portuguese rivers have a Hydrographic Basin Plan; however, their application should be more efficient, especially in the Rivers Ave and Leça. The management plan in the Douro is more efficient than in the other two rivers.