Rainfall variability and geohidroecological functions of areas managed by traditional communities in Paraty (Rio de Janeiro, Brazil)
Authors: Fraga Joana , Coelho Netto Ana Luiza , Ribeiro de Oliveira Rogério 
Published: June 2022

&lt;p&gt;Located in the southern coast of Rio de Janeiro state, the cities of Angra dos Reis and Paraty are marked by the mountainous features of Serra do Mar and extreme rainfall events, which many times trigger mass movements and floods, causing serious damage to local population. However, in 2014, Paraty was affected by a water crisis which caused conflicts related to water supply among rural communities in the Carapitanga basin. Paraty had a long land-use history based on swidden agriculture, practice by local traditional communities, resulting in a forest mosaic in different successional stages that covers 86% of the total municipality area. In the 1970s, a federal plan aiming to stimulate tourism in the region generated several land-use changes: an intense process of real estate speculation, population increase, creation of conservation units, the suppression of traditional practices and the forest regrowth in abandoned areas. Previous studies have already emphasized the recovery of biodiversity and the rehabilitation of ecological functions after traditional practices, but there is comparatively little understanding of how the hydrological functioning is affected by various phases of forest regrowth. This study aims to investigate geohidroecological functions of managed areas and analysed historical rainfall records (1968-2010) to characterize the 2014 event in the Carapitanga basin, as well as observe possible pluviometric trends. Three areas were selected in &lt;em&gt;Quilombo do Campinho&lt;/em&gt; community (formed by descendants of former maroon colonies) to perform data collection: 30- and 50-year-old forests (F30; F50) regenerated after the abandonment of swiddens and a recently implemented (10 years) agroforestry area (AF). The variables monitored, collected and analysed throughout the research were: precipitation, forest interception (F30; F50), vegetation structure and composition, soil moisture and saturated hydraulic conductivity (Ksat) at depths of 20, 50, 80, 120, 200 cm and soil physical properties (at depths of 20, 50, 80, 120 cm). The analysis of rainfall historical variation showed that precipitation values of 2014 were lower (1555 mm) than historical average (2231 mm), but within historical variation of less rainy years (&lt;1804 mm). In fact, records suggest an increase of rainy years in the last decades. &amp;#160;In general, Ksat decreased with depth in all sites, specially from 20 cm to 50 cm. AF presented highest values of Ksat in most depths (50, 80, 120 cm) and preservation of moisture in higher depths (120, 200 cm), possibly influenced by higher Ksat, lower interception and lower root density. The 30-year-old forest had the greatest diversity of tree species (6,3 &lt;em&gt;spp&lt;/em&gt;./m&amp;#178;) and the 50-year-old forest the greatest structural diversity of individual trees and, consequently, the greatest precipitation interception (F30=19%; F50=26%). The results suggest that these areas play important roles in environmental system regulations, with some particularities among them, possibly generating a geohidroecological mosaic (more data is needed). Pluviometric trends and more recent policies for the region, encouraging new constructions and increased human occupation, consequently causing deforestation, raise alerts for the political and economic model in course, that without an adequate planning, can improve population vulnerability to extreme events.&lt;/p&gt;