ESTRUTURA LENHOSA E HIDRODINÂMICA DO ESCOAMENTO SUPERFICIAL EM UMA ÁREA DE CAATINGA

Abstract

The water and soil natural resources in the semi-arid tropics are under pressure and are inclined to degradation due to the severe environment and shallow soils, in ecologically sensitive regions to anthropic actions. In view of the above, this work aimed to characterize the structure and the hydraulic evaluation of the surface water typical of interrill erosion, in a caatinga area of Serra Talhada country in Brazil. For this the quadrant point method was used in the structural characterization of the vegetation of caatinga for trees and shrubby species. Laminar surface regime was generated from a rain simulator in 2 m2 plots with caatinga in the humid and dry seasons. The differentiations of the flow rates, average surface water speed and the Reynolds number, had demonstrated the significant effect of seasonality on the characteristic laminar surface water of the interrill erosion. The observed tree-shrub structure of caatinga contributed to the low values of runoff coefficient of the interrill areas, demonstrating the efficiency of caatinga, and its resulting vegetated cover in the interception of rain and, in the delay of the surface water. The low values runoff also observed also contributed to the high rates of infiltration of water.