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Made available in DSpace on 2022-04-29T08:41:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Similar to most countries, the Brazilian water resources management considers topographically delineated catchment as a territorial unit for policy implementation. Yet, previous studies have shown that catchments are not hydrologically isolated, and topographic limits often neglect the groundwater boundaries. Thus, studies on effective catchment areas are promising for shedding light on inter-catchment groundwater flow. Here, we investigated the deviation between the topographic and effective areas across Brazil. We applied the effective catchment area index (ECI) to 733 Brazilian catchments and identified the most influencing attributes on the ECI by using principal component and random forest analyses (PCA and RFA, respectively). Further analysis was carried out by contrasting the ECI values against the expected range of the Budyko curve, considering both topographic and effective catchment areas (classic and adjusted framework, respectively). We noted that nearly 32% of the Brazilian catchments presented more than 30% of difference between the effective area and its topographic boundaries. In general, the more arid biomes in Brazil—the Cerrado and Caatinga—are prone to have smaller effective areas while larger effective areas were mostly found in the Atlantic Forest biome, a humid tropical region with a higher mean elevation. Our findings indicate that the aridity index was the main driving factor and negatively correlated with ECI followed by mean slope, precipitation seasonality, and mean elevation. We highlight the potential of adopting a pooling of catchments based on their interconnectivity to minimize management costs while maximizing synergies and lessening trade-offs between ecosystem functioning and water transfer processes. Our results contribute to a better country-wide understanding of hydrological connectivity among catchments and highlight the need to consider the effective catchment area to overcome water-food-energy security challenges on multiple scales. Department of Hydraulics and Sanitation São Carlos School of Engineering University of São Paulo, SP Department of Civil and Environmental Engineering Bauru Engineering College São Paulo State University – UNESP, SP Faculty of Engineering Architecture and Urbanism and Geography Federal University of Mato Grosso do Sul, MS Department of Civil and Environmental Engineering Bauru Engineering College São Paulo State University – UNESP, SP CAPES: 001 FAPESP: 2015/03806-1 FAPESP: 2019/24292-7 FAPESP: 2021/14016-2 CNPq: 309752/2020-5 CNPq: 441289/2017-7

We assess whether a Payments for Ecosystem Services (PES) programme met its objectives of reducing soil erosion and yielding water in an environmental protected area, the Guariroba River Basin, Midwestern Brazil. We measured rainfall and water discharge throughout 2012 and 2016. During the same period, soil and water conservation practices were performed in the basin, such as: building level terraces and riparian vegetation recovery. We separated streamflow into baseflow and direct runoff, then we evaluted the baseflow index that indicated that groundwater significantly contributes to total flow. Therefore, to investigate the effects on streamflow, we performed a trend analysis in the baseflow time series using the Mann-Kendall test. In addition, we analysed the efficiency of soil erosion regulation practices over time, considering the total payment and the trends found in the baseflow. Whereas precipitation records present a decreasing trend (1 mm month−1), baseflow tends to increase by 0.018 m3 s−1 in the same period. Our findings show that soil conservation practices performed in the basin increase baseflow and also provide a better resilience to endure extreme events such as drought based on an increase in forest areas and soil conservation practices such as level terrace.