Erosive Process Control in the Brazilian Semiarid Region

Abstract

The adoption of measures to prevent and control erosive processes requires information about the factors affecting the erosion and the sediment transport conditions. However, the sediment yield of a basin depends on the availability of eroded material and the sediment transport capacity. Thus, the objective of this study was to identify the factors that affect the sediment transport capacity at different spatial scales in an area with caatinga vegetation. The study was carried out in the Iguatu Experimental Basin, in the state of Ceará, Brazil, from 2009 to 2014, by monitoring two scale levels: watershed with 2.06 ha, and erosion plot with 20 m². The variables evaluated for the rainfall events were precipitation, intensity of rainfall, antecedent soil moisture, precipitation of the antecedent five days, consecutive dry days, peak flow, runoff depth, and sediment yield. During the study period, 263 rainfall events (>2 mm) and 86 events generating runoff were recorded. Three Principal Components (PC) were developed using the Principal Component Analysis, which explained more than 79% of the total variance. Variables connected to the kinetic energy capacity of the rainfall to disaggregate soil particles, the energy for sediment transport, and the soil water content were framed in the CP1, CP2, and CP3, respectively. In the evaluated scales, the sediment yield presented a high correlation with the runoff depth, which indicates limiting conditions for sediment yield by the mass flow energy.

Preliminary experimental data on surface runoff and soil loss in the Caatinga

“…Planosols and Luvisols typically have low permeability in deep horizons due to increased clay in‐depth (Araújo Filho et al, 2017). High clay content relationships between B and A horizons create differences in total porosity and hydraulic conductivity between surface and subsurface horizons (Cunha et al, 2010; dos Santos et al, 2018). Although the increase in the clay content of the Bt horizon where the plots were installed is not enough to provide a high textural relationship, it guarantees greater expression of the expansion and contraction of the abundant mineral mass in expandable clays as a function of moisture compared with the surface horizon.…”

“…The variability of surface runoff and soil loss results exemplifies how hydrological dynamics and surface erosion processes are dynamic, resulting from a complex combination of controlling factors and generating agents, and this is even more heterogeneous in semi‐arid environments (dos Santos et al, 2018; Hasanuzzaman et al, 2018; IPCC, 2019; Nadal‐Romero & García‐Ruiz, 2018; Wang et al, 2016; Wolka et al, 2021) Despite the variability, the importance of use/coverage in the control of erosive processes is notorious (Albuquerque et al, 2001; Oliveira, 2015; Santos et al, 2007; Silva et al, 2016; Sirvent et al, 1997; Xavier, 2016, 2021).…”

“…horizons due to increased clay in-depth (Araújo Filho et al, 2017). High clay content relationships between B and A horizons create differences in total porosity and hydraulic conductivity between surface and subsurface horizons (Cunha et al, 2010;dos Santos et al, 2018).…”

“…It is known that semi‐arid environments are highly prone to erosion due to the low density of vegetation cover (Leite et al, 2018; Wang et al, 2016) and spatio‐temporal rainfall variability (dos Santos et al, 2011, 2016, 2018). The Brazilian semi‐arid region is considered the most populated semi‐arid region on the planet.…”