Impact of Overgrazing on Diffuse and Concentrated Erosion: Case Study in the Sloping Lands of South Africa

Chaplot, Vincent; Mutema, Macdex

doi:10.3390/hydrology9070121

Cited by 3 publications

(2 citation statements)

References 23 publications

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“…Until 2011, DONGA research remained mostly constant at one to two publications per year, but it has increased over the last decade (Figure 6). However, several of these newer papers present new findings from continued research at the earlier sites, for example, in the Sneeuberg (Boardman et al, 2003, 2015; Favis‐Mortlock et al, 2018; Keay‐Bright & Boardman, 2007), the Sandspruit catchment (Olivier et al, 2016, 2018), and near Potshini village (Chaplot, 2013; Chaplot et al, 2011; Chaplot & Mutema, 2022; Grellier et al, 2012; Podwojewski et al, 2020).…”

Section: Resultsmentioning

confidence: 99%

“…Headward erosion was assessed byGrellier et al (2012) from a time series of aerial imagery and fieldwork to calculate soil loss as 25.7 t ha À1 yr À1 Chaplot et al (2011), Chaplot (2013,. andChaplot & Mutema (2022) estimated soil loss rates between 2.3 and 4.8 t ha À1 yr À1 from gully walls from rainfall experiments and erosion pins installed on sidewalls, respectively. Soil loss rates from gully erosion contributed an average of 122% compared to the soil loss risk map from Le Roux et al(2008) (Table5).…”

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Intersecting views of gully erosion in South Africa

Olivier

Wiel

Clercq

2022

Earth Surf Processes Landf

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Gully erosion is an environmental problem recognized as one of the worst land degradation processes worldwide. Insight into regional gully perturbations is required to combat the serious on‐ and off‐site impacts of gullying on a catchment management scale. In response, we intersect different perspectives on gully erosion‐specific views in South Africa (SA), a country that exhibits various physiographic properties and spans 1.22 million km2. While the debate surrounding gully origin continues, there is consensus that anthropogenic activities are a major contemporary driver. The anthropogenic impact caused gullying to transcend climatic, geomorphic, and land‐use boundaries, although it becomes more prominent in central to eastern SA. Soil erodibility plays a crucial role in what extent of gully erosion severity is attained from human impact, contributing to the east–west imbalance of erosion in SA. Soil erosion rates from gullying and badlands are limited but suggest that it ranges between 30 and 123 t ha−1 yr−1 in the more prominent areas. These soil loss rates are comparable to global rates where gullying is concerned; moreover, they are up to four orders of magnitude higher than the estimated baseline erosion rate. On a national scale, the complexity of gullying is evident from the different temporal timings of (re)activation or stabilizing and different evolution rates. Continued efforts are required to understand the intricate interplay of human activities, climate, and preconditions determining soil erodibility. In SA, more medium‐ to long‐term studies are required to understand better how changing control factors affect gully evolution. More research is needed to implement and appraise mitigation measures, especially using indigenous knowledge. Establishing (semi)‐automated mapping procedures would aid in gully monitoring and assessing the effectiveness of implemented mitigation measures. More urgently, the expected changes in climate and land‐use necessitate further research on how environmental change affects short‐term gully erosion dynamics.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Intersecting views of gully erosion in South Africa

Olivier

Wiel

Clercq

2022

Earth Surf Processes Landf

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An integrated assessment of erosion drivers facilitating gully expansion rates—A near century multi‐temporal analysis from South Africa

Claassen,

Botha,

Linol

2024

Land Degrad Dev

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Rural areas in the Eastern Cape Province of South Africa are severely affected by gully erosion, yet little is known about the rates at which these features are expanding. This study explores the areal extent, physical mechanisms, rates, and drivers of gully expansion with the aim of investigating how erosion rates fluctuate in response to temporal variations of drivers over the last century. Investigations involved the creation of an erosion inventory geo‐database, the identification of area‐specific physical expansion mechanisms, an assessment of static and dynamic drivers, and a multi‐temporal study of 25 gullies in the Mthatha area. Results show gully erosion affects 2.3% of the study area, with gullies exhibiting an average annual areal increase of 2.08%, a sidewall retreat rate of 0.2 m/y, and a headcut retreat of 1.03 m/y over an 82‐year period between 1938 and 2020. A multi‐temporal case study of the Ngwevana Gully showed average annual areal growth rates ranging from 3.9% between 1938 and 1948 to 0.7% between 2017 and 2020. Findings indicate that although gullies consistently expand their areal footprint, they do so at fluctuating rates. An assessment of erosion drivers reveals that temporal promotion or suppression of these erosion rates occurs in response to the complex and dynamic interactions of both natural mechanisms and anthropogenic activities. In Mthatha, the periods of increased rates of erosion are linked to large‐scale flooding events during drier climate cycles, which were further exacerbated by invasive dryland agricultural practices, inappropriate land use, haphazard infrastructure development, and rapid population increases facilitated by past Apartheid settlement laws.

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