Do Brazilian Catchments Gain or Lose Water?

Código

XXIV-SBRH0407

Autores

Gabriela Gesualdo, Dimaghi Schwamback, Alex Naoki Asato Kobayashi, Paulo Tarso Sanches de Oliveira, Jullian Souza Sone, Andre Almagro, Luis Eduardo Bertotto, Maria Vitória da Silva Garcia, Edson Cezar Wendland

Tema

SE03.B - Conectividade de Água e Sedimentos

Resumo

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 the effective area of catchments are a promising alternative for considering 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 the Principal Component and Random Forest Analysis (PCA and RFA, respectively). Further analysis of consistency was carried out contrasting the ECI values against the Budyko framework. Our results indicate that 15% and 16% of the catchments analyzed present the effective area smaller than half (strong losing water condition) and larger than double (strong gaining water condition) compared with the topographic area, respectively. The aridity index was the main driving factor and negatively correlated with ECI followed by mean slope, precipitation seasonality, and mean elevation. In general, the more arid biomes in Brazil, the Cerrado, and Caatinga, showed a smaller effective area concentration while larger effective areas were mostly found in the Atlantic Forest biome, a humid tropical region with a higher mean elevation. Our results contribute to a better country-scale 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.