Riparian vegetation affected by bank erosion in the Lower São Francisco River, Northeastern Brazil

Abstract

Changes in the hydrological regime of the Lower São Francisco River, located in Northeastern Brazil have brought negative environmental impacts, jeopardizing the flora and fauna of a global biodiversity hotspot, due to implementation of hydroelectric power dams and surface water withdrawal for irrigation in public and private perimeters. Remnants of the riparian stratum associated to the riverbank destabilization in six fragments were studied by surveying trees, shrubs, herbs, and aquatic species. The calculation of the Factor of Safety (FS) was performed in order to understand the riverbank's stability related to soil texture and vegetation cover. An overall number of 51 botanic families distributed in 71 genera and 79 species were recorded, predominantly from the families Mimosaceae, Myrtaceae, and Fabaceae. The fragmented riparian vegetation is mostly covered by secondary species under a strong anthropogenic impact such as deforestation, mining and irrigation, with an advanced erosion process in the river margins. Strong species that withstand the waves present in the river flow are needed to reduce the constant landslides that are mainly responsible for the river sedimentation and loss of productive lands. A lack of preservation attitude among the local landholders was identified, and constitutes a continuing threat to the riparian ecosystem biodiversity.

Effects of riparian vegetation on the structure of the marginal aquatic habitat and the associated fish assemblage in a tropical Brazilian reservoir

“…In the present study, the marginal habitat with natural riparian vegetation showed a greater array of habitat elements, such as macrophytes and underwater structures. The overall lower littoral depths in the study sites where the natural riparian cover was removed is in accordance with other studies (Holanda et al 2005) which indicate that the removal of the riparian vegetal cover may lead to bank destabilization and increased erosion and sedimentation in the aquatic habitat. In the present study, a high proportion of sand and small gravel in the aquatic substrate composition in areas where the riparian cover was removed are an indication that the exposure of the soil and the consequent erosion are adding coarse sediments to the substrate.…”

Estabilização de taludes marginais com técnicas de bioengenharia de solos no Baixo São Francisco

“…Estradas, lotes residenciais e agrícolas têm sido destruídos pelo acelerado processo erosivo levantado em 57 focos, caracterizado pela desestabilização dos taludes nas margens do rio São Francisco, conforme relato de Casado et al (2002) e Holanda et al (2005).…”

Degradações Ambientais No Rio Colônia No Trecho Urbano Do Município De Itororó, Bahia

“…Os processos erosivos nas margens de rios, acentuados ou não, pela retirada da mata ciliar, são manifestações mais perceptíveis da complexa readaptação da morfologia do canal em busca de uma nova estabilização e das modificações na dinâmica do sistema fluvial (HOLANDA et al, 2005;HOLANDA et al, 2009). Sabe-se que as matas ciliares podem atuar como redutor do assoreamento, sendo um importante suporte de segurança para o equilíbrio do ecossistema e suas relações essenciais (CASTRO et al, 2013).…”