Water erosion prediction at a national scale for South Africa

Roux, J. Le; Morgenthal, Theunis; Malherbe, Johan; Pretorius, DJ; Sumner, Paul

doi:10.4314/wsa.v34i3.180623

Cited by 116 publications

(68 citation statements)

References 22 publications

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“…Although rainfall is the main agent causing soil erosion in the KwaZulu‐Natal and eastern parts of the Eastern production region, intense wind erosion causes significant soil losses in the Eastern and Western production regions (Le Roux et al., 2008). Strong winter winds from July to September are common in both the Western and Eastern regions, whereas strong winds associated with intense thunderstorms occur during summer in all maize production regions.…”

Section: Soil Management For Improved and Sustainable Rainfed Maize Pmentioning

confidence: 99%

“…Soils are degraded through rigorous soil tillage, maize monoculture, and fallow periods, which are common. Soil organic matter and nutrients are depleted and there is significant soil loss through wind and water erosion (Le Roux, Morgenthal, Malherbe, Pretorius, & Sumner, 2008; Mills & Fey, 2003). Although more sustainable practices have been proposed (Kassam, Mkomwa, & Friedrich, 2016; Smith, Kruger, Knot, & Blignaut, 2017; Swanepoel, Swanepoel, & Smith, 2017), adoption of management practices that limit degradation has been slow (Findlater, Kandlikar, & Satterfield, 2019).…”

Section: Introductionmentioning

confidence: 99%

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A prospectus for sustainability of rainfed maize production systems in South Africa

2020

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The rainfed maize (Zea mays L.) production systems of South Africa require an integrated approach to use the limited soil available water more efficiently, and to increase system productivity and sustainability. The soils across the major maize production regions are highly susceptible to wind and water erosion. Rigorous soil tillage, maize monoculture, and fallow periods are common, which depletes the soil from organic matter and nutrients. Despite the pressing need for transforming the highly degraded rainfed maize production systems, adoption of more sustainable management approaches has been limited, likely due to a shortage of local scientific field trials to evaluate current and alternative maize agronomic management practices. Erratic interseasonal rainfall patterns cause high variability in maize grain yields. Major challenges associated with no‐tillage are poor crop establishment, subsoil compaction, and high maize grain yield variability. The use of fallow in the maize–fallow production system leads to excessive runoff and soil erosion losses despite increased maize grain yields. Crop intensification and alternative crops are needed to increase rainfall water use efficiency and lower fallow frequency. The use of cover and forage crops may provide the opportunity to diversify and intensify maize production systems. Cover crop biomass could be beneficial in livestock‐integrated production systems providing livestock feed in either winter or summer. Research is drastically required to improve the understanding of current South African rainfed maize production systems and to facilitate the development of fitting sustainable agronomic management practices.

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Section: Soil Management For Improved and Sustainable Rainfed Maize Pmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A prospectus for sustainability of rainfed maize production systems in South Africa

2020

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“…Previous soil erosion mapping and modelling studies, however, indicate that large parts of the Tsitsa River Catchment are severely eroded (Le Roux et al, 2008;Mararakanye & Le Roux, 2012). Nevertheless, the studies provide insufficient information about the sediment yield (SYLD) in the catchment.…”

Section: Introductionmentioning

confidence: 99%

Sediment Yield Potential in South Africa's Only Large River Network without a Dam: Implications for Water Resource Management

Roux

2017

Land Degrad Dev

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Soil erosion not only involves the loss of fertile topsoil but is also coupled with sedimentation of dams, a double barrel problem in semi‐arid regions where water scarcity is frequent. Due to increasing water requirements in South Africa, the government is planning water resource development in the Mzimvubu River Catchment, which is the only large river network in the country without a dam. However, previous soil erosion studies indicate that large parts of the catchment are severely eroded. These studies, nonetheless, focussed only on rill and interill erosion processes and provided insufficient information about sediment yield. The present study maps and models the sediment yield potential by considering important connectivity factors (flow path length, slope steepness and surface roughness) over a 5‐year timeframe (from 2007 to 2012). Sediment yield contribution from rill–interrill erosion was modelled with ArcSWAT‐2012, whereas gully erosion contributions were estimated using sequential gully mapping with SPOT 5 imagery followed by gully‐derived sediment modelling in a GIS. Integration of the rill–interrill and gully results provided the total sediment yield potential, with an average of 5100 Mg km−2 y−1. The average sediment yield where the irrigation and hydropower dams are planned is around 20 000 Mg km−2 y−1. This study provides relative differences of the potential sediment yield and a framework to predict sediment yield to assist area‐specific rehabilitation in large, ungauged catchments. Without catchment rehabilitation, the life expectancies of the future irrigation and hydropower dams could be 55 and 43 years, respectively. Copyright © 2017 John Wiley & Sons, Ltd.

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“…Intensive sugarcane cultivation as a mono‐cropping system increases soil degradation (Van Antwerpen, ; Du Preez et al, ). Approximately 85% of the country can be considered as degraded (Garland et al, ) mainly due to soil erosion, which has been identified as a key driver responsible for more than 70% of land degradation of South African soils (Le Roux et al, ; Le Roux, ). As such, there is an urgent need to estimate soil loss and identify problematic areas for improved catchment‐based erosion control and sediment management strategies.…”

Section: Introductionmentioning

confidence: 99%

“…As such, there is an urgent need to estimate soil loss and identify problematic areas for improved catchment‐based erosion control and sediment management strategies. To‐date, soil erosion research in the Province of KwaZulu‐Natal has tended to focus on macro‐scale gully erosion, while sheet erosion at varying spatial scales has received little research attention (Beckedahl, ; Le Roux et al, ; Dlamini et al, ). Le Roux et al .…”

Section: Introductionmentioning

confidence: 99%

Assessment of soil erosion under rainfed sugarcane in KwaZulu‐Natal, South Africa

Abdalla

Dickey

Hill

et al. 2019

Natural Resources Forum

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Soil erosion from agricultural land use runoff is a major threat to the sustainability of soil composition and water resource integrity. Sugarcane is an important cash and food security crop in South Africa, subjected to an intensive soil erosion, and consequently, severe land degradation. This study aimed to investigate soil erosion and associated soil and cover factors under rainfed sugarcane, in a small catchment, KwaZulu‐Natal, South Africa. Three replicated runoff plots were installed at different slope positions (down, mid and upslope) within cultivated sugarcane fields to monitor soil erosion during the 2016–2017 rainy season. On average, annual runoff (RF) was significantly greater from 10 m2 plots with 1163.77 ± 2.63 l/m/year compared to 1 m2 plots. However, sediment concentration (SC) was significantly lower in 10 m2 (0.34 ± 0.04 g/l) compared to 1 m2 (6.94 ± 0.24 g/l) plots. The annual soil losses (SL) calculated from 12 rainfall events was 58.36 ± 0.77 and 8.84 ± 0.20 t/ha from 1 m2 and 10 m2 plots, respectively. The 1 m2 plot, SL (2.4 ± 1.41 ton/ha/year) in the upslope experienced 33% more loss than the midslope and 50% more loss than the downslope position. SL was relatively lower from the 10 m2 plots than the 1 m2 plots, which is explained by high sediment deposition at the greater plot scale. SL was negatively correlated with the soil organic carbon stocks (r = −0.82) and soil surface cover (r = −0.55). RF decreased with the increase of slope gradient (r = −0.88) and soil infiltration rate (r = −0.87). There were considerable soil losses from cultivated sugarcane fields with low organic matter. These findings suggest that to mitigate soil erosion, soil organic carbon stocks and vegetation cover needs to be increased through appropriate land management practices, particularly in cultivated areas with steep gradients.

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Water erosion prediction at a national scale for South Africa

Cited by 116 publications

References 22 publications

A prospectus for sustainability of rainfed maize production systems in South Africa

A prospectus for sustainability of rainfed maize production systems in South Africa

Sediment Yield Potential in South Africa's Only Large River Network without a Dam: Implications for Water Resource Management

Assessment of soil erosion under rainfed sugarcane in KwaZulu‐Natal, South Africa

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