Abstract This study aimed to evaluate the influence of the addition of coconut (coir) fibers on the microstructural, hydraulic and mechanical behavior of an unsaturated compacted soil. Specimens were molded and compacted, forming composites with 0%, 0.1%, 0.5% and 1% fiber in relation to their dry mass. The characterization of pores from the soil and fiber soil mixtures was performed by the Mercury Intrusion Porosimetry tests. Suction values were obtained through the filter paper method and soil water retention curves were adjusted with the Durner model due to the bimodal behavior. Tensile strength values were obtained from the indirect tensile strength test (Brazilian tensile test) for specimens with different suction values. It was found that the increase in fiber content in the material lead to a non-linear increase in macropores, which affected both the hydraulic and mechanical behavior of the soil. Furthermore, the shape of the soil water retention curve was preserved, but there were changes in the values of first and second air entry and residual suction. The tensile strength was negatively influenced, reaching a reduction of about 30% in the situation with higher fiber content. However, for higher levels, the behavior of the soil changed from brittle to ductile, increasing the supported deformations.

Resumo A partir do conhecimento das áreas de risco de inundação urbana e do banco de dados do cadastro ambiental rural, que permite conhecer a localização das nascentes de cursos d’água, o artigo associa e avalia as áreas de risco e nascentes, propondo ações no âmbito das informações geradas. O estudo abrangeu 10 municípios da região do Vale do Paraíba, mapeados pelo Instituto de Pesquisas Tecnológicas (IPT), com risco de inundação e a situação das nascentes (áreas preservadas, consolidadas e a serem recompostas). Os resultados revelaram, para os municípios avaliados, que 10.324 nascentes foram cadastradas e, para todos os municípios, a quantidade de áreas preservadas é superior em relação às consolidadas. Além disso, há carência de projeto de recomposição da vegetação em nascentes de cursos d’água causadores de inundação nos municípios estudados, mesmo após alterações no Código Florestal. Tais informações podem ser utilizadas para subsidiar instituições locais, que atuam na revegetação de áreas desmatadas, e iniciativas que visem à mitigação de risco de inundação das áreas avaliadas.

Abstract The knowledge of urban flood risk areas associated with the rural environmental register database allows to identify where small rivers begins. This article combines and assesses the risk prone areas with headwaters and proposes actions. The goal of this work was to evaluate the relationships between flood risk and the environmental conditions of headwaters (both in preserved, consolidated areas and to be reforested) of 10 municipalities in the Paraiba Valley, previously mapped by the Institute of Technological Research (IPT). The results showed that, for the municipalities evaluated, 10,324 headwaters were registered and, for all municipalities the quantity of preserved areas is higher in comparison with the consolidated areas. Furthermore, there is a lack of vegetation restoration project in rivers that causes flooding in the studied municipalities, even after changes in the Brazilian Forest Code. These results provide valuable information to the local institutions that conduct actions for the restoration of deforested areas and several other initiatives that aim to mitigate flood risk in the areas assessed in this study.