Hydrological and environmental analysis of the Pirajibu-Mirim watershed, Sorocaba, SP, Brazil

Abstract

The watershed of the Pirajibu-Mirim River, in Sorocaba-SP, contributes to production and the municipal water supply, and is located in a high-priority region for the implementation of a Payment for Environmental Services (PES) program. In this context, this study aimed to evaluate the conservation of its water springs and environmental compliance with the legislation of Permanent Preservation Areas (PPAs). A macroscopic diagnosis of the water springs was therefore made in the field in order to subsequently classify their condition. The assessment of environmental compliance with the PPAs was performed with the aid of RapidEye (2014) satellite images and the Quantum GIS 1.6 program. The results indicated that water quality stands out positively, while the land use and occupation of the springs areas showed negative results. No water spring is located in protected areas and only one was found on an agricultural farm; none had signs indicating its presence. Most of them show evidence of human disturbance, such as degradation of vegetation and garbage dumping. The evaluation of environmental compliance demonstrated that 30.7% of the PPAs lack adequate vegetative cover, and thus may potentially be included in an intervention program for recovery due to degradation. The profile analysis of the properties that have water springs indicated the predominance of lands without any commercial use that included recreational country houses. The work indicated some environmental and socioeconomic characteristics of the watershed that can support public policy for the conservation of water resources in the region, if considered in the establishment of a PSA program.