Abstract The objective of this study was to evaluate the input of suspended sediment from the slope toe in the São Francisco River channel, in Northeast Brazil, under different soil bioengineering techniques. Sediments were collected in the years of 2013, 2014 and 2015, in five transects crossing the river channel. Sediment input in the sampling points was higher in the year of 2013, i.e., the year of the highest river discharge. Sediment supply to the river channel for a period of 3 years (2013, 2014 and 2015), was evaluated at 20, 40 and 60% depth, along five different transects (P1= riverbank, P2= beginning of the thalweg, P3= middle of the thalweg, P4= end of the thalweg, and P5 = margin of the side sandybar), oriented by the presence or absence of erosion control techniques (treatments) such as: 1-Natural Vegetated Slope; 2-Vegetated Riprap; 3-Eroded Slope; 4-Live Cribwall and 5-Vetiver grass Contour Line. Sediments input was different in all evaluated transects, and the one identified as Eroded Slope at 20% depth presented the lowest amount of suspended sediment load. There was a decrease in the total amount of suspended sediment in the evaluated periods, probably due to the progressive decrease in the river discharge, and the protection provided by the soil bioengineering techniques.

Resumen Este estudio evalúa la entrada de sedimentos en suspensión de la punta de la pendiente del cauce del río São Francisco, en el noreste de Brasil, bajo diferentes técnicas de bioingeniería de suelos. Los sedimentos se recolectaron en 2013, 2014 y 2015, en cinco transectos que cruzan el cauce del río. La entrada de sedimentos en los puntos de muestreo fue mayor en el año 2013, es decir, el año de la mayor descarga del río. El suministro de sedimentos al cauce del río por un período de 3 años (2013, 2014 y 2015), fue evaluado a 20, 40 y 60% de profundidad, a lo largo de cinco transectos diferentes (P1 = ribera, P2 = inicio del thalweg, P3 = medio del thalweg, P4 = final del thalweg, y P5 = margen de la barra arenosa lateral), orientados por la presencia o ausencia de técnicas de control de erosión (tratamientos) tales como: 1-Talud Vegetado Natural; Riprap de 2 vegetaciones; Pendiente 3-erosionada; 4-Live Cribwall y 5-Vetiver grass Contour Line. La entrada de sedimentos fue diferente en todos los transectos evaluados, y el identificado como Pendiente Erosionada al 20% de profundidad presentó la menor cantidad de carga de sedimentos en suspensión. Hubo una disminución en la cantidad total de sedimentos en suspensión en los períodos evaluados, probablemente debido a la disminución progresiva del caudal del río y la protección que brindan las técnicas de bioingeniería de suelos.

RESUMO A técnica de semeadura direta vem se destacando nos projetos de recuperação florestal pela redução de custos na implantação e tem sido cada vez mais utilizada. Este trabalho foi realizado com o objetivo de avaliar a emergência, sobrevivência e estabelecimento de espécies florestais nativas, por meio de sementes em áreas de mata ciliar no Rio Piauitinga, município de Lagarto, SE. As espécies utilizadas foram Libidibia ferrea var. leiostachya (Benth.) L. P. Queiroz, Cassia grandis L. f., Cecropia pachystachya Trec., Enterolobium contortisiliquum (Vell.) Morong e Guazuma ulmifolia Lam. O experimento em campo foi implantado em Delineamento em Blocos Casualizados (DBC) com quatro repetições, em esquema fatorial, testando-se as cinco espécies com e sem tratamento para superação de dormência. A semeadura direta mostrou-se uma técnica viável para a área de estudo apenas para as espécies L. ferrea var. leiostachya, E. contortisiliquum e Cassia grandis, utilizando-se sementes com e sem dormência.

ABSTRACT The direct seeding technique stands out for forest restoration projects due to savings in deployment costs and has been increasingly used. This work was carried out with the objective of assessing emergence, survival and establishment of native forest species, by means of seeds, in riparian areas of Piauitinga River, in the municipality of Lagarto-SE. The species used were Libidibia ferrea var. leiostachya (Benth.) L.P.Queiroz., Cassia grandis L.F., Cecropia pachystachya Trec., Enterolobium contortisiliquum (Vell.) Morong and Guazuma ulmifolia Lam. The field work was performed in a randomized block design (RBD) with four replications in factorial scheme, testing five species with and without treatment for overcoming of dormancy. It was observed that direct sowing is a viable technique for the area of study only for the species L. ferrea var. leiostachya, E. contortisiliquum and Cassia grandis, using seeds with and without dormancy.