Technical contributions to territorial planning and the use of ecosystemic services in a hydrographic basin with a water deficit in the Atlantic Rainforest of Brazil

anglais. Abstract The catchment basin of the Dois Rios River (R2R) (3159 km2) unites the climatic and environmental effects typical of areas located on the leeward side of mountain chains. It has a deficient water balance, with sparse and very specific wet areas. This study identifies delimitation areas, and characterizes and groups those basins and floodplains which show the greatest capacity for producing ecosystemic services related to maintaining the continuity of water resources in the R2R basin. Locations with higher pluviometric indices (1500 to 2800 mm/year) were selected and grouped into micro basins with the highest potential for capturing rainfall due to their being on the leeward side of the mountains in the region (with their slopes oriented to permit them to capture humidity and concave plane curvature). The 42 basins formed 4 groups, from which the 17 micro basins with the highest probability of providing ecosystemic services were chosen, belonging to Groups III and IV. Within these groups, the 498 floodplains with the highest potential for offering ecosystemic services (Group D) present the greatest capacity for water retention and sustainable effects (high average circularity index, higher altitudes and low occupation rates). The correct use of 0.0006% of the basin can guarantee the direct flow of the drainage for the entire basin. This strategy only requires renaturation measures, discipline with regard to the land uses and strict observance of the processes which generate ecosystemic services in the floodplains of these basins, resulting in relevant socio-environmental benefits for all socioeconomic segments within the R2R basin.

portugais. Resumo A bacia do rio Dois Rios (R2R) (3.159 km²) recolhe os efeitos climáticos e ambientais típicos de zonas situadas a sotavento de cadeias montanhosas. Tem balanço hídrico deficitário, havendo poucos e específicos locais úmidos. Este estudo identifica, espacializa, caracteriza e agrupa as planícies de inundação com maior habilidade em produzir serviços ecossistêmicos relacionados à perenidade de recursos hídricos na bacia R2R. Foram segregados locais com maiores índices pluviométrico (1500 a 2800 mm/ano), agrupados em microbacias com maior potencial de captação em função de estarem a sota-vento na região (slopes oriented to permit them to capture humidity and concave plane curvature). As 42 bacias formaram 4 grupos, onde levantou-se 17 microbacias com alto potencial de fornecer serviços ecossistêmicos pertencentes aos Grupos III e IV. Nestes grupos, 498 planícies de inundação com maior potencial de oferta de serviços ecossistêmicos (grupo D) apresentam habilidades para retenção hídrica e efeitos de perenização (high average circularity index, higher altitudes and low occupation rates). O uso correto de 0,0006% pode garantir o escoamento direto das drenagens de toda a bacia. Está estratégica implicaria em medidas de renaturalização, disciplinamento dos usos e estrita observação dos processos que geram serviços ecossistêmicos nas planícies das bacias, trazendo relevantes benefícios socioeconômicos para todos os segmentos da bacia do R2R.