RAINFALL CHARACTERIZATION AND SEDIMENTOLOGICAL RESPONSES OF WATERSHEDS WITH DIFFERENT LAND USES TO PRECIPITATION IN THE SEMIARID REGION OF BRAZIL

Jacques Carvalho Ribeiro Filho,Helba Araújo De Queiroz Palácio,Eunice Maia De Andrade,José Bandeira Brasil,Júlio César Neves Dos Santos

doi:10.1590/1983-21252017v30n222rc

Abstract

ABSTRACT The objective of this work was to evaluated the precipitation characteristics (depth, I30 and erosivity) and their effects on sediment production in three watersheds under different managements of land use 35-year regenerating Caatinga (RC), thinned Caatinga (TC), which underwent thinning of trees with diameter smaller than 10 cm; and deforested Caatinga (followed by burning and pasture) (DC). The experimente was conducted in the central, tropical semiarid region of the State of Ceará, Brazil. The precipitation events, surface runoff and sediment production were monitored from 2010 to 2015. The precipitation characteristics were subjected to Pearson's correlation at 1 and 5% of significance and the events that produced sediments in each watershed were hierarchically grouped by hierarchical cluster analysis technique. Two hundred precipitation events were recorded, with 23 (RC), 18 (TC) and 43 (DC) events producing sediments. The use of thinning (TC) decreased the sediment production by 53.5%, while the deforestation, burn and pasture cultivation (DC) increased soil losses by 14%, compared with the RC. The sediment production was greatly correlated with the I30 in the three watersheds, denoting the erosion process great dependence on the precipitation intensity.

Highlights

Soil loss is dangerous to the environment of terrestrial ecosystems when exceeds the tolerable level and may be intensified by human disturbances (LIU et al, 2012)
Few studies assessed the effects of changes in land use in the Brazilian semiarid on hydrological and sedimentological processes, which cause irreparable damages, such as siltation and eutrophication of water bodies
The obtaining of a better correlation between erosivity and soil losses is limited by the high variability and low information on precipitation physical characteristics (ALBUQUERQUE et al, 2005; LIMA et al, 2013; WESTER; WASKLEWICZ; STALEY, 2014)

Summary

Introduction

Soil loss is dangerous to the environment of terrestrial ecosystems when exceeds the tolerable level and may be intensified by human disturbances (LIU et al, 2012). The intensification of human activities on natural resources, especially in semiarid regions, affect the soil physical properties and hydrological and sedimentological processes of watersheds, such as water retention, runoff and sediment production (CHAMIZO et al 2012). Few studies assessed the effects of changes in land use in the Brazilian semiarid on hydrological and sedimentological processes, which cause irreparable damages, such as siltation and eutrophication of water bodies. The obtaining of a better correlation between erosivity and soil losses is limited by the high variability and low information on precipitation physical characteristics (ALBUQUERQUE et al, 2005; LIMA et al, 2013; WESTER; WASKLEWICZ; STALEY, 2014). The main process generating runoff in the Brazilian semiarid region is the Hortonian (precipitation intensity exceeding the infiltration capacity). The extrapolation of estimates between scales is limited by the heterogeneity of watersheds, usually not represented at small scale (BOIX-FAYOS et al, 2006)

Objectives

Methods

Findings

Conclusion