AUTODEPURATION CAPACITY OF A STRETCH OF THE CORUMBATAÍ RIVER, SP, BRAZIL

Abstract

The depuration rate of the low stretch of the Corumbataí River, SP, was evaluated by using the K2 index, considering the importance of the quality and quantity of the water as a vital source of drinking water. Water samples were taken in the humid/hot and dry/cold seasons in the Corumbataí River and two tributaries, the Passa-Cinco River and the Ribeirão Água Vermelha, measuring the speed of the water, discharge, depth, dissolved oxygen (OD), biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total nitrogen (TN). The watercourse of the Corumbataí River receives large amounts of organic loads proceeding from diffuse sewage from domestic and agro-industrial effluents, discharged without previous treatment, causing a high degree of degradation of its water quality. The lower stretch of the Corumbataí still has a high depuration rate, mainly in the dry/cold period, reaching approximately 70.3%. This autodepuration capacity is probably due to the accented declivity in the stretch studied, to its meandering course and base rock formation, and to the presence of riparian forest. In this sense, this study can contribute information to decision making at the municipal and communitty levels in the “Comitê das Bacias Hidrográficas PCJ”, as this watershed is an important drinking water source.