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

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.

位于巴西圣保罗州索罗卡巴市的皮拉吉布-米林河（Pirajibu-Mirim River）流域，不仅支撑区域生产活动与市政供水保障，同时是环境服务付费（Payment for Environmental Services, PES）计划实施的高优先级区域。在此研究背景下，本研究旨在评估该流域泉点的保护现状，以及其是否符合永久保护区（Permanent Preservation Areas, PPAs）相关立法要求。为此，研究团队通过实地踏勘完成了泉点的宏观诊断，进而对其健康状态开展分级评定。永久保护区环境合规性评估则依托2014年RapidEye卫星影像与Quantum GIS 1.6地理信息系统软件完成。研究结果显示，泉点水质整体表现良好，但泉点周边区域的土地利用与占用现状却呈现负面特征。流域内无一处泉点位于法定保护区范围内，仅1处泉点坐落于农业用地中，且所有泉点均无明确标识牌标注其位置。多数泉点存在人类活动干扰痕迹，包括植被退化与垃圾倾倒等问题。环境合规性评估结果表明，30.7%的永久保护区缺乏足够的原生植被覆盖，因生态退化具备被纳入生态修复干预计划的潜在可能。对拥有泉点的地块开展的属性分析显示，该区域内多数地块未开展商业化开发，其中包含休闲型乡村住宅项目。本研究明确了该流域的部分环境与社会经济特征，若将其纳入PSA计划的制定流程，可为该区域水资源保护相关公共政策的制定提供决策支撑。