SOIL LOSS, INFILTRATION AND RUNNOF RATES IN SOIL UNDER DESERTIFICATION
IN THE BRAZILIAN SEMI-ARID REGION: INFLUENCE OF VEGETATION COVER AND
RAINFALL INTENSITY
Abstract
Desertification is a problem in regions with arid, semi-arid and dry
sub-humid climates and is characterized by the degradation of natural
resources. The influence of vegetation cover and rainfall intensity on
the dynamics of water infiltration, surface runoff and soil loss was
measured in situ in a Desertification Zone in the semi-arid
region of Brazil. Twenty-four plots were evaluated in two areas, each
with the same type of soil that is predominant in the region: 1) Luvisol
with dense vegetation cover (LD) and 2) Luvisol with sparse vegetation
cover (LS). Rainfall of 60 and 100 mm h -1 was
simulated with a rainfall simulator. Soil hydraulic conductivity, soil
water retention curves and soil carbon and nitrogen stocks were also
determined. Water infiltration was greater in the LD (53 mm h
-1) compared to the LS (15 mm h -1),
while the runoff rates were 27 mm h -1 for the LD and
61 mm h -1 for the LS. Rainfall intensity
significantly influenced when runoff started and the runoff rate,
accelerating soil loss. Vegetation cover significantly influenced the
total soil carbon and nitrogen stocks, as well as the saturated
hydraulic conductivity of the soil. This is the first study in the
semi-arid desertification region of Brazil that used simulated rainfall
to assess the effects rain intensity on soil properties. The results of
this study can be used as a reference for calibrating erosion models in
areas undergoing a desertification process