Rates, factors, and tolerances of water erosion in the Cerrado biome (Brazil): A meta‐analysis of runoff plot data

Abstract

Due to the high rainfall erosivity and highly erodible soils, water erosion is severe in Brazil. Soil and ecosystem degradation occurs when erosion exceeds on‐ and off‐site soil loss tolerances, with significant socioeconomic and environmental impacts. In the last 50 years, the Brazilian Cerrado had 53% of its original vegetation converted to agriculture and pastureland. Although erosion plot studies exist in the region, the data are fragmented and unexplored, hindering the development of soil conservation policies. The objective of the present research was to compile, systematize, and statistically analyze the existing erosion plot data in the Brazilian Cerrado, correlating the observed results with different environmental and management factors, and with the corresponding soil loss tolerances. Twenty runoff plot datasets of the Brazilian Cerrado, encompassing 5 states, 10 sites, 108 plots, and 360 plot·years were compiled and thoroughly analyzed. Mean annual rainfall, runoff, and soil loss were 1443.5 mm year−1, 83.1 mm year−1, and 8.9 Mg ha−1 year−1, respectively. After the data were normalized with respect to plot length, steepness, and climate, runoff and soil loss were found to be significantly higher in soils with impermeable horizons and in land uses without permanent soil cover (p < 0.05). Erosion under permanently covered plots was below the on‐ and off‐site soil loss tolerances. A power equation provided the best fit between plot runoff and soil loss (R2 = 0.71; p < 0.05), indicating that runoff volume, easier to estimate, could be used as a proxy for upslope erosion. Although erosion plot data cannot be extrapolated to the whole landscape, the research results provide useful elements for the development of sound conservation policies in the Cerrado and in other similar savannas of the world.

Introduction to the Women in Geomorphology special issue

“…Field (26) Atkins et al, 2023;Bernatek-Jakiel & Nadal-Romero, 2023;Biausque et al, 2022;Brooks et al, 2022;Bywater-Reyes et al, 2022;Chin, 2022;Gervasi et al, 2021;Glover et al, 2022; Goodman et al, in press;Guiney & Lininger, 2022; Gurnell et al, 2022;Harvey et al, 2022;Hinshaw et al, 2022;Hooke, 2022;Konlechner & Hilton, 2022;Kooijman et al, 2022;Lane et al, 2022;Lefebvre et al, 2022;Marchetti et al, 2022;McKeon et al, 2022;Mol & Grenfell, 2022;Mossa & Chen, 2022;Opalka et al, 2022;Patton et al, 2022;Quock et al, 2022;Regalla et al, 2022;Reitman et al, 2022;Sampietro-Vattuone et al, 2021;Schoch-Baumann et al, 2022;Souza Fonseca et al, 2022;Spiske et al, 2022;Thompson et al, 2022;Uphues et al, 2022;Valentine et al, 2022;Van Soest et al, 2022;Wohl, 2022;Zhang et al, 2022 (Continues)…”

“…Papers addressing process and form in coastal environments include examinations of dune morphodynamics and evolution (Hovenga et al, 2021; Konlechner & Hilton, 2022; Kooijman et al, 2022); the influence of sorting and bedforms on the magnitude of coastal eolian transport (Uphues et al, 2022); coastal changes in response to an extreme storm (Spiske et al, 2022); estuarine mangrove dynamics (Glover et al, 2022) and the morphology of estuarine bedforms (Lefebvre et al, 2022); geotechnical properties of salt marsh soils (Brooks et al, 2022) and tidal wetland development (McKeon et al, 2022); seasonal morphodynamics of intertidal bars (Biausque et al, 2022); and wave impacts and cliff erosion (Thompson et al, 2022). Papers addressing hillslopes and mass movements include interactions between raindrop impacts and particle settling velocities in sheet flow (Bako et al, 2022); a review and synthesis of soil piping (Bernatek‐Jakiel & Nadal‐Romero, 2023); a review of erosion plot studies in the Brazilian Cerrado (Souza Fonseca et al, 2022); seasonal variations in gully erosion (Agostini et al, 2022); influences on Mediterranean badlands formation (Nadal‐Romero et al, 2022); numerical models of landslide effects on the cosmogenic isotope signal of fluvial sediment (Schide et al, 2022); surface slip on strike‐slip faults (Reitman et al, 2022); post‐fire patterns of rock weathering (Mol & Grenfell, 2022); precursory indicators of alpine rockfall (Hendrickx et al, 2022); grain‐size distributions of mass movement deposits (Harvey et al, 2022); influences on landslide initiation based on field observations and numerical modelling (Patton et al, 2022); physical experiments on debris‐flow erosion (Roelofs et al, 2022); and comparison of digital elevation models built from different data sources (Atwood & West, 2022). Glacial geomorphic studies are represented by papers examining topographic controls on ice flow and glacier front recession (Davies et al, 2022); moraine dynamics in the context of climate change (Rowan et al, 2022); and streamlined sub‐glacial bedforms (McKenzie et al, 2022).…”

Natural Denudation Versus Anthropogenically Accelerated Erosion in Central Brazil: A Confrontation of Time and Space Scales

“…According to Borrelli et al (2021), there are 77 published Brazilian studies dealing with soil erosion, among those 56 provided soil losses by water erosion ranging from 0.1 to 155 t ha −1 yr −1 , with a median value of 12.4 t ha − 1 yr −1 (≈1,000 mm kyr −1 with a soil density of about 1,200 kg m −3 ). From an equivalent of 360 plot yr across five Brazilian states, Fonseca et al (2021) retrieved soil losses ranging from a minimum of 8.9 to a maximum of 205.7 t ha −1 yr −1 . They also showed that soil losses under conservation agriculture experience erosion rates that are 70% lower than those measured under conventional agriculture, underlining the importance of permanent vegetation cover to reduce tillage and limit runoff and thus soil erosion (see also Anache et al, 2017Anache et al, , 2019Castro et al, 1999;Londero et al, 2021).…”

“…Land use impacts on soil erosion were also evaluated in Southern Brazil, using inventories of meteoric 10 Be (Schoonejans et al, 2017) and soil weathering indices (Vanacker et al, 2019) in deeply weathered soils. In Brazil, there is also a large corpus of studies using the universal soil loss equation (see e.g., Gomes et al, 2019;and references in Rosa et al (2023)) and experimental runoff plots (e.g., Fonseca et al, 2021). According to Borrelli et al (2021), there are 77 published Brazilian studies dealing with soil erosion, among those 56 provided soil losses by water erosion ranging from 0.1 to 155 t ha −1 yr −1 , with a median value of 12.4 t ha − 1 yr −1 (≈1,000 mm kyr −1 with a soil density of about 1,200 kg m −3 ).…”

Seismic Signatures and Site Characterization of an Intermittent Stream in Dry and Flood Conditions: An Implication for Soil Losses and Landslide Triggering

“…In the case of the Cerrado region of Brazil, erosion by water is a crucial soil threat [16][17][18] . The environmental dynamics in hydrographic basins, such as intensified erosion processes, siltation and decreased oxygen available in rivers and lakes, among other factors, may be inferred from the eroded sediments loads related to surface runoff and water infiltration into the soil [19] .…”