Manejo em bacia hidrográfica do riacho Jacu: produção de sedimentos, dimensionamento de faixa de vegetação ciliar e salinidade da água em barragem subterrânea.

Abstract

Sediment delivery ratio is the parameter which involves the sediment yield in watersheds and sums all sediment promptly detachment by several ways of erosion. Evaluating technologies of setting the riparian vegetation, based on yield sediment in watersheds are increasingly important to environmental preservation. Thus, the aim of this research was to set the width of riparian vegetation in Jacu semiarid stream (Pernambuco) in function of sediment delivery ratio and sediment yield. Therefore, it was calculated the rates of interrill and rill erosion by yield testing under shrub and bare Inceptisols conditions, and it was carried out direct measurement campaigns of suspended sediment and bedload, by means of US DH – 48 e US BLH – 84, respectively. The sediment yield obtained in Jacu stream was considered low. The soil loss due to interril erosion under bare conditions equal to 8.43 t ha-1 was considered high, as well as the same way for the values of rill erosion with erodibility equal to 0.0021142 kg N-1 s-1 and critical shear stress (τc) equal to 2.34 Pa. The mean value of sediment delivery ratio of Jacu watershed was equal to 0.165 and ranged from 0.29 (2008) to 0.026 (2010). This variation is associated with the natural variability of semiarid environment, indicating the necessity of assessment in a large period of years to improve the knowledge about the sediment delivery ratio of Jacu semiarid watershed. The determination of 15 m for the width of riparian vegetation from Jacu stream in function of sediment yield was considered promising for the small watershed conditions.