Determinant Pluviometric Characteristics of Sediment Transport in a Catchment With Thinned Vegetation in the Tropical Semiarid

Abstract

Knowing determinant factors of erosive process is essential to adopt soil conservationist and loss-mitigation measures. Therefore, the objective of this work was to assess the correlation between rainfall characteristics and sediment transport in the Semiarid region of Brazil. The study was conducted at the Iguatu Experimental Basin in the state of Ceará, Brazil, in a watershed with area of 1.15 ha. The vegetation was thinned by removal of plants with diameters below 10 cm, and the area remained with an arboreous cover of 60%. The following variables were evaluated from 2012 to 2016: rainfall depth (mm), rainfall duration (hours), maximum rainfall intensity in 5, 10, 15, 20, 30, 45, and 60 minutes (mm h-1), mean rainfall intensity (mm h-1), rainfall depth in the previous 5 days (mm), runoff depth (mm), and transported sediment (kg ha-1). The records showed 158 rainfall events, 27 with surface runoff and 24 with sediment transport. The correlations were investigated by multivariate analysis of principal components (PC). The model explained 84% of total variance with four PC-PC1, PC2, PC3, and PC4 were formed, respectively, for disaggregating power of rainfall on soil particles, represented by the rainfall intensities; soil water content; runoff depth and sediment transport; and rainfall duration and interval between rainfalls. The highest factorial weight was found for the maximum intensity in 20 minutes, indicating the need for further hydrological studies focused on this variable at basin scale in areas of the Semiarid region of Brazil subjected to thinning of the vegetation.

Flow Measurement Methods in Small Tributaries of the Teles Pires River, Southern of the Amazon Hydrological Region

“…The conditions of soil use and coverage, the density of vegetation cover [41], and the type and physical water characteristics of the soil are important factors that control the dynamics of water and sediments in a river basin [9,42], in addition to climatic [12,29], edaphic [9,43], and physiographic characteristics [13]. The latter refers to the area and density of the drainage network, the shape, slope, and sinuosity of the channel that influence the generation, volume, speed, and direction of the surface runoff flow [42] and the production and transport of sediments [6,7].…”

“…In this regard, collecting hydrological information on the surface water availability of natural watercourses can serve as a subsidy for planning and the proper management of water and soil. One of the components of the hydrological cycle that can be monitored and quantified is the flow of a river, called surface, subsurface and base runoff, which is dependent on the characteristics of rainfall (intensity, quantity, duration, and frequency), vegetation cover, soil, climate [11,12], and the physiographic characteristics of the watershed [13].…”

Dynamics of Sediment Transport in the Teles Pires River Basin in the Cerrado-Amazon, Brazil

“…Sediment production in the context of a watershed depends on the interaction between the intensity and duration of the rainfall and the density of the plant cover [3,4], the type of soil, and management practices [1,2,38,39]. In turn, sediment transport is the result of the slope of the channel, the increase in flow speed, and the increase in flow, especially during the rainy season [6,33].…”

“…The erosion process can be accelerated by human activity via the removal of plant cover, intensive mechanized tillage of the soil, and the absence of soil conservation practices, which alter the physical and water characteristics of the soil, making it more susceptible to loss by erosion [1,2]. With this approach, the combined effects of human activity and rainfall characteristics (e.g., intensity, blade, quantity, duration, frequency, and pattern of occurrence) influence the infiltration, storage, and drainage capacity of water in the soil [3,4]. This can result in excessive soil loss from water erosion and the production of sediment in water ways.…”

Impacto de Secas e Antropização na Dinâmica da Cobertura Florestal em Fragmento do Domínio Fitogeográfico da Caatinga

“…A exploração agrícola com práticas de agricultura itinerante (onde consta o desmatamento e a queimada desordenada), tem modificado tanto o estrato herbáceo como o arbustivo-arbóreo. A intensificação do uso do solo, bem como seu emprego além da capacidade natural de regeneração dos ecossistemas vem causando na região da caatinga perdas na biodiversidade da fauna e da flora, erosão do solo (Palácio et al, 2016;Andrade et al, 2018;Sousa et al, 2020), sedimentação dos reservatórios e dos rios (Araújo, 2003), com consequente declínio da atividade econômica e da qualidade de vida da população (Araújo Filho, 2013). Extremos climáticos intensos associados à degradação do solo, poderiam levar à aceleração do processo de desertificação no semiárido; assim, a possibilidade de secas mais intensas e prolongadas poderia elevar ainda mais o grau de exposição e vulnerabilidade das populações que habitam o semiárido, especialmente daqueles mais pobres (Marengo et al, 2011).…”