Pagamentos por serviços ecossistêmicos visando à manutenção dos recursos hídricos

Abstract

Changes in land use-land cover by human activities affect hydrological processes and the supply of water ecosystem services. Forests are positively associated with water quality and Brazilian legislation through the Native Vegetation Protection Law (NVPL) (Law no . 12.651/2012) established command and control instruments, such as Permanent Preservation Areas (PPA) and Legal Reserve (LR) to avoid deforestation. However, the areas established by the NVPL are insufficient to avoid diffuse pollution and the deterioration of water bodies. In this context, Payments for Ecosystem Services (PES), an economic incentive instrument, can be an alternative tool for protecting water resources. Therefore, our main objective is to understand how PES programs can be an instrument to enhance the supply of water environmental services in agricultural watersheds. The study was developed in the Sarapuí river basin, SP, using 2019 orbital images from the Sentinel-2ª satellite, with a spatial resolution of 10m, to identify soil use and cover. We carried out water collections every two months in 6 watersheds during 2022 and compared the water quality parameters with collections in 2013/14. We use statistical tests to identify the relationship between land use-land cover with parameters at the scale of the watersheds and PPAs and changes in land use-land cover. We compared the protection of priority areas for conservation to maintain water resources with areas legally protected by the LPVN. In addition to the legal protection scenario (30m PPA), a 100m PPA scenario was simulated to compare the protection of priority areas by the legal scenario and a more conservative scenario. Finally, we used data available from the “Biota-Fapesp Florestal Code” project to identify the deficit of native vegetation on rural properties and also to characterize properties according to size. We identified that all anthropogenic uses in watersheds negatively impact water quality (pasture, agriculture, and urban) and that forest cover is the most positively associated with water quality. Most of the variation in water quality was explained at the watershed scale, which emphasizes the importance of adopting conservation strategies in the watershed as a whole and not only in PPAs. Furthermore, almost 70% of the highest priority areas for PES are outside the limits of PPAs, and there are few deficits in LR and PPAs, which demonstrates that there are no additional conservation incentives on the part of the NPVL. A 100m PPA would increase the protection of these areas by 150%. Therefore, PPAs can be an instrument to finance the conservation and forest restoration of priority areas, especially those not included in the LPVN, to expand the adoption of better agricultural practices and basic sanitation to minimize the impacts of anthropogenic uses on water quality.