EFFECTS OF CLIMATIC SEASONALITY AND URBANIZATION ON THE WATER QUALITY OF ACARAÚ RIVER, SOBRAL (CE)

Abstract

This study aimed at analyzing the effects of climate seasonality and of urbanization in the determination of the Acaraú river Water Quality Index - WQI, located in the intraurban stretch of the city of Sobral (Ceará/Brazil). The area studied extends for 15 km encompassing a river system with entrance zones (non-urbanized), mixture zones (highly urbanized) and exit zones (moderately urbanized). WQI allows assessing the quality of raw water. To calculate it, nine parameters of water quality were assessed. Analytical procedures with water samples in five collection points were adopted. The study took place between March/15 and March/16 comprehending the dry season, rainy pre-season and the wintry quarter. Results indicated that hydroclimate factors and the forms of land use and occupation directly influenced the WQI values - in which values of “bad” quality are mainly observed in the dry season in the intraurban areas of Sobral. This may indicate that non-treated charges of domestic effluent get to the main canal of Acaraú river. Therefore, it is concluded that climate seasonality associated with forms of land use and occupation plays an important role in the water quality of Acaraú river in Sobral.