Sediment Delivery Ratio from a small Semiarid Watershed of Brazil

Abstract

Assessing technologies based on sediment yield in watersheds is increasingly important to determine the delivery rate. This work aimed to determine values of sediment delivery of the hydrographic basin of the river Jacu in the semiarid of Pernambuco and its relations with the soil and vegetation. Therefore, it was calculated the rates of interrill and rill erosion by yield testing under shrub and uncovered 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 uncovered 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 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 in the year 2008 to 0.026 in 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.