Environmental services in watersheds with small declivity: fluvial marine plains

Abstract Fluvial marine plains harbor environments with reduced declivity, but with different environmental attributes that may be relevant ecosystem services in their watersheds, which can be transformed into opportunities for the development of environmental services payments. This study digitally spatialized part of the ecosystem services related to water availability in the microbasins of the Guandu Basin Hydrographic Basin, the main source of water supply for the metropolitan region of Rio de Janeiro, based on geo-environmental factors and the effects of transposition of watersheds, in order to facilitate the formulation of public policies regarding environmental services. The excerpts with the highest potential for producing environmental services from subsurface water flows, Topographic Wetness Index-ITU (ITU > 11), flat formation and low altimetry (< 40 m), are close to the old silted thalwegs, which can be potentialized by the effects of transposition, notably in the APA Guandu conservation unit. These areas should be prioritized in public and private water systems’ preservation programs. The areas near the transposition canals feature environmental services that depend directly on the transposition, and may be subject to management, as found in Guandu conservation unit. Flat areas with (7