Avaliação do desempenho de biotécnicas no controle da erosão em taludes

Abstract

Soil erosion has caused environmental impacts in slopes of embankments in rural areas as in urban areas. Slope stabilization and erosion control on slopes is possible by permanent vegetation establishment, which is facilitated by the use of bioengineering techniques, such as using biodegradable blankets. In order to evaluate the efficiency of biodegradable blankets in establishment of permanent vegetation and erosion control on slopes, was conducted an experiment on the campus of UFRPE in Cabo de Santo Agostinho, PE. On 33.5° degrees (66% slope) was evaluated the soil and water losses by erosion under natural rainfall condition in five erosion plots: Plot A - sisal fiber and hydroseeding of Brachiaria Decumbens; Plot B - plant of emerald grass (Zoysia japonica Steud); Plot C - sisal fiber blanket and vetiver grass (Chrysopogon zizanioides); Plot D – handmade biomantle was produced from sisal cords and hydroseeding of Brachiaria Decumbens e Plot E - biomantle with biodegradable blanket of coconut fiber and hydroseeding of Brachiaria Decumbens. The experimental period was between 01 june and 24 august 2016, rain precipitation was 356,50 mm, with 4.566,70 MJ ha-1 mm h-1 of erosivity. The plots with greater soil loss were sisal fiber blanket and grassy vetiver (Chrysopogon zizanioides) – Plot C and plant of emerald grass (Zoysia japonica Steud) - Plot B, with 49.560 kg ha-¹ and 27.500 kg ha-¹, respectively. The others plots showed smaller losses of soil, 18,760 kg ha-¹; 17,390 kg ha-¹; and 9,730 g ha-¹. The greatest losses water occurred in the plots sisal fiber and hydroseeding of Brachiaria Decumbens (281.69 l/10m2); Sisal fiber blanket and Vetiver grass (Chrysopogon zizanioides) (202.75 l/10m2) and Biomantle was produced from Sisal cords and hydroseeding of Brachiaria Decumbens (152.06 l/10.m2); the other techniques, biomantle with biodegradable blanket of coconut fiber and hydroseeding of Brachiaria Decumbens and plant of emerald grass (Zoysia japonica Steud) had losses of 95.56 l/10m2 and 67.31 l/10m2, respectively. According to the period of study it is concluded that the Sisal fiber blanket and grassy vetiver (Chrysopogon zizanioides) and the Plant of emerald grass (Zoysia japonica Steud) were not adequate in protecting soil losses, for having presented major losses. The sisal fiber and hydroseeding of Brachiaria Decumbens and the sisal fiber blanket and vetiver grass (Chrysopogon zizanioides) were shown inadequate in protecting due to water loss.