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<ITU< 11) have their ecosystem services transferred from subsurface water flows to surface water flows and are dependent more on meteorological phenomena and on ways to manage heavy rain showers through their use, especially as altimetry and slope increase.

Sustainable provision of raw water based on the management of ecosystem services in small watersheds

“…These results show that the area has a low natural water provision capacity, given that the watershed predominantly tends to flow superficially with the volume of precipitation received. This result agrees with that found by Bueno et al (2019) who used the topographic index of humidity as indicator of water-producing areas and concluded that the study area has a low capacity for water provision.…”

“…With respect to water provision, the ecosystem service offered in the study area is restricted to small areas of outcrop, as related by Bueno et al (2019). Thus, water supply and sediment production were applied by means of a water balance and by measuring the volume of sediment that left the system.…”

“…Thus, water supply and sediment production were applied by means of a water balance and by measuring the volume of sediment that left the system. In addition, the water-flow pattern was described in the different hydrogenetic zones, as proposed by Bueno et al (2019), through the local relief and description of soil profiles.…”