Estimativa do assoreamento e avaliação da qualidade das águas do Açude Velho na cidade de Campina Grande/PB.

Abstract

The present work had as objective to carry out a study on the sedimentation process and on the water quality of the Açude Velho in Campina Grande / PB. For the diagnosis of water quality, physico-chemical and microbiological indicators were determined in 10 sample points, spatially distributed by the reservoir, during the period from March to September 2016. The bathymetric survey was carried out with the purpose of estimating the volumes of water and sediment inside the reservoir, besides allowing the identification of the areas most affected by the silting process. The results obtained presented a useful water volume of 475,677.49 m³. It was verified that approximately 23% of the total volume of the dam is occupied by sediments and, when compared with the data presented by Castro (1994) for the year 1990, Açude Velho had its storage capacity reduced by 7.7%. According to the analyzed indicators, the marginal points of the dam were inferior in quality to the central points. According to comparisons with the Resolution 357/2005 of CONAMA, the water of the Old Açude in the non-rainy period presented BOD compatible with water of class 3 (10 mg / L). However, in the rainy period, the BOD promoted a decrease in water quality presenting higher values than allowed in the mentioned class. In general, the Açude Velho features characteristics of a compromised quality eutrophic aquatic body for most of the prevailing uses.