Land degradation in South Africa: Conventional views, changing paradigms and a tradition of soil conservation

Land degradation with its direct impact on vegetation, surface soil layers and land surface albedo, has great relevance with the climate system. Assessing the climatic and ecological effects induced by land degradation requires a precise understanding of the interaction between the land surface and atmosphere. In coupled land-atmosphere modeling, the low boundary conditions impact the thermal and hydraulic exchanges at the land surface, therefore regulates the overlying atmosphere by land-atmosphere feedback processes. However, those land-atmosphere interactions are not convincingly represented in coupled land-atmosphere modeling applications. It is partly due to an approximate representation of hydrological processes in land surface modeling. Another source of uncertainties relates to the generalization of soil physical properties in the modeling system. This study focuses on the role of the prescribed physical properties of soil in high-resolution land surface-atmosphere simulations over South Africa. The model used here is the hydrologically-enhanced Weather Research and Forecasting (WRF-Hydro) model. Four commonly used global soil datasets obtained from UN Food and Agriculture Organization (FAO) soil database, Harmonized World Soil Database (HWSD), Global Soil Dataset for Earth System Model (GSDE), and SoilGrids dataset, are incorporated within the WRF-Hydro experiments for investigating the impact of soil information on land-atmosphere interactions. The simulation results of near-surface temperature, skin temperature, and surface energy fluxes are presented and compared to observational-based reference dataset. It is found that simulated soil moisture is largely influenced by soil texture features, which affects its feedback to the atmosphere.

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Effects of land use changes and conservation measures on land degradation under a Mediterranean climate

Solid Earth Discussions ◽

10.5194/sed-7-115-2015 ◽

2015 ◽

Vol 7 (1) ◽

pp. 115-145 ◽

Cited By ~ 4

Author(s):

Y. Mohawesh ◽

A. Taimeh ◽

F. Ziadat

Keyword(s):

Land Use ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Land Degradation ◽

Soil Conservation ◽

Land Use Changes ◽

Conservation Measures ◽

Stone Walls ◽

Effects Of Land Use ◽

Soil Conservation Measures

Abstract. Land degradation resulting from improper land use and management is a major cause of declined productivity in the arid environment. The objectives of this study were to examine the effects of a sequence of land use changes, soil conservation measures, and the time since their implementation on the degradation of selected soil properties. The climate for the selected 105 km2 watershed varies from semi-arid sub-tropical to Mediterranean sub-humid. Land use changes were detected using aerial photographs acquired in 1953, 1978, and 2008. A total of 218 samples were collected from 40 sites in three different rainfall zones to represent different land use changes and different lengths of time since the construction of stone walls. Analyses of variance were used to test the differences between the sequences of land use changes (interchangeable sequences of forest, orchards, field crops, and range), the time since the implementation of soil conservation measures, and rainfall on the thickness of the A-horizon, soil organic carbon content, and texture. Soil organic carbon reacts actively with different combinations and sequences of land use changes. The time since stone walls were constructed showed significant impacts on soil organic carbon and the thickness of the surface horizon. The effects of changing the land use and whether the changes were associated with the construction of stone walls, varied according to the annual rainfall. The results help in understanding the effects of land use changes on land degradation processes and carbon sequestration potential and in formulating sound soil conservation plans.

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Soil Conservation and Control of Land-Degradation

An Introduction to Agroforestry ◽

10.1007/978-3-030-75358-0_18 ◽

2021 ◽

pp. 445-474

Author(s):

P. K. Ramachandran Nair ◽

B. Mohan Kumar ◽

Vimala D. Nair

Keyword(s):

Land Degradation ◽

Soil Conservation ◽

And Control

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Eco-Holistic Soil Conservation to support Land Degradation Neutrality and the Sustainable Development Goals

CATENA ◽

10.1016/j.catena.2020.104823 ◽

2021 ◽

Vol 196 ◽

pp. 104823

Author(s):

Juan Albaladejo ◽

Elvira Díaz-Pereira ◽

Joris de Vente

Keyword(s):

Sustainable Development ◽

Land Degradation ◽

Soil Conservation ◽

Sustainable Development Goals ◽

The Sustainable Development ◽

Development Goals

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Unpacking Changing Multi-Actor and Multi-Level Actor Ties in Transformative Spaces: Insights from a Degraded Landscape, Machubeni, South Africa

Land ◽

10.3390/land9070227 ◽

2020 ◽

Vol 9 (7) ◽

pp. 227

Author(s):

Menelisi Falayi ◽

James Gambiza ◽

Michael Schoon

Keyword(s):

South Africa ◽

Collective Action ◽

Land Degradation ◽

Network Evolution ◽

Clustering Coefficient ◽

Edge Density ◽

Policy Outcomes ◽

Local Municipality ◽

Multi Level ◽

Over Time

The loss of ecosystem services through land degradation continues to be a significant concern for policymakers and land users around the world. Facilitating collective action among various actors is regarded as imperative in halting land degradation. Despite extensive research on collective action, there have been few studies that continuously map social ties and detect network evolution as a way of enabling longitudinal analysis of transformative spaces. This paper seeks to examine the changing dynamics of multi-actor and multi-level actor ties over a period of two years in Machubeni, South Africa. To do this, we used social network analysis to detect continuities and/or discontinuities of multi-actor and multi-level actor ties over time. Overall, edge density, clustering coefficient, and reciprocity scores steadily increased over the two years despite a decline in the number of active organisations within the network. Our results demonstrate that the proportion of strong ties gradually increased over time across three governance networks. However, multi-level linkages between the local municipality and the local organisations remained weak due to a lack of trust and collaborative fatigue. While the transformative space has succeeded in enhancing collaboration and knowledge sharing between local organisations and researchers, further long-term engagement with government agencies might be necessary for promoting institutional transformations and policy outcomes, and building network resilience in complex polycentric governance systems.

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Review: Design norms for soil and water conservation structures in the sugar industry of South Africa

Water SA ◽

10.4314/wsa.v45i1.04 ◽

2019 ◽

Vol 45 (1 January) ◽

Author(s):

Daniel Otim ◽

Jeff Smithers ◽

Aidan Senzanje ◽

Rianto Van Antwerpen

Keyword(s):

South Africa ◽

South African ◽

Water Conservation ◽

Soil Conservation ◽

Soil Loss ◽

Sugar Industry ◽

Empirical Models ◽

Soil And Water Conservation ◽

The South ◽

Soil And Water

This paper contains a critical review of the norms employed in the design of soil and water conservation structures in the South African sugar industry and highlights research needs in order to update them. Sugarcane in South Africa is grown on wide-ranging soils, sometimes in non-ideal climates and on steep topographies where soils are vulnerable to erosion. A consequence of unsustainable soil loss is reduction in field production capacity. Sugarcane fields are protected against erosion through, inter alia, the use of engineered waterways, contour banks and spill-over roads. The South African Sugarcane Research Institute (SASRI), previously known as the South African Sugar Experiment Station (SASEX), developed a nomograph to easily compute the maximum width of field panels based on soil type, tillage method, replant method, surface structures to control runoff, surface cover and slope. This was followed by guidelines and norms for the design of soil and water conservation structures. However, the nomograph was developed based on an acceptable soil loss of 20 t·ha−1·yr−1, yet soil formation rates in South Africa range between 0.25 and 0.38 t·ha−1·yr−1. Comparisons between design norms in the National Soil Conservation Manual and norms used in the sugar industry clearly show discrepancies that need to be investigated. The design of soil conservation structures includes the design of both contour bank spacing and hydraulic capacity. The sustainable soil loss method is recommended in the design of contour spacing and it determines contour spacing based on evaluation of site-specific sheet and rill erosion potential of the planned contour spacing while the hydraulic design employs Manning’s equation. Considering that increases in both design rainfall and design floods are anticipated in South Africa, it is necessary to incorporate these projections in the design of soil and water conservation structures. Many soil loss models exist, of which empirical models are the most robust and provide stable performances. The majority of empirical models are lumped models which estimate average annual soil loss. The Modified Universal Soil Loss Equation (MUSLE) estimates event-based erosion and, given that the majority of soil erosion occurs during a few extreme events annually, the design norms should be updated using the MUSLE.

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Nature Divided: Land Degradation in South Africa

South African Journal of Botany ◽

10.1016/s0254-6299(15)30366-5 ◽

2003 ◽

Vol 69 (1) ◽

pp. 116 ◽

Cited By ~ 1

Author(s):

Laco Mucina

Keyword(s):

South Africa ◽

Land Degradation

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South African Land Degradation Monitor (SALDI) – A German – South African SPACES collaboration to advance land degradation assessments

10.5194/egusphere-egu2020-21870 ◽

2020 ◽

Author(s):

Jussi Baade ◽

Andreas Kaiser ◽

Keyword(s):

South Africa ◽

South African ◽

Land Degradation ◽

Land Surface ◽

Soil Degradation ◽

Assessment Tools ◽

Automated System ◽

Observation Data ◽

Clean Water ◽

Cooperative Research

South Africa is greatly affected by land degradation, partly due to the high variability of its climatic conditions, the strong population growth and resulting economic demands. Thus reaching a number of SDGs, like achieving food security (#2), access to clean water (#6), and the sustainable use of terrestrial (#15) and marine (#14) resources represents a clear challenge under the present global change pressures. Land degradation has been linked in South Africa to the terms veld degradation and soil degradation and has been addressed by numerous measures. But there is still uncertainty on the extent of human induced land degradation as compared to periodic climate induced land surface property changes.In cooperation with South African institutions and stakeholders (ARC-ISCW, SAEON, SANParks, SANSA, Stellenbosch University and University of the Free State, Equispectives Research and Consulting Services, Nuwejaars Wetlands SMA), the overarching goal of SALDi is to implement novel, adaptive, and sustainable tools for assessing land degradation in multi-use landscapes in South Africa. Building upon the state of the art in land degradation assessments, the project aims to advance current methodologies for multi-use landscapes by innovatively incorporating inter-annual and seasonal variability in a spatially explicit approach. SALDi takes advantage of the emerging availability of high spatio-temporal resolution Earth observation data (e.g. Copernicus Sentinels, DLR TanDEM-X, NASA/USGS Landsat program), growing sources of in-situ data and advancements in modelling approaches. Particularly, SALDi aims to:<ol><li>i) develop an automated system for high temporal frequency (bi-weekly) and spatial resolution (10 to 30 m) change detection monitoring of ecosystem service dynamics,</li> <li>ii) develop, adapt and apply a Regional Earth System Model (RESM) to South Africa and investigate the feedbacks between land surface properties and the regional climate,</li> </ol>iii)&#160;&#160;&#160; advance current soil degradation process assessment tools for soil erosion, as this process represents an intrinsic limiting factor for biomass production and other regulating, supporting and provisioning ecosystem services, like providing clean water.The aim of this presentation is to introduce this new cooperative research project to the EGU Community and to seek new opportunities for collaboration.

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