South African Land Degradation Monitor (SALDI) – An overview of recent advancements

2021 ◽  
Author(s):  
Jussi Baade ◽  
Christiane Schmullius ◽  
Marcel Urban ◽  
Harald Kunstmann ◽  
Patrick Laux ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Land Degradation ◽  
Ecosystem Service ◽  
Land Surface ◽  
Soil Degradation ◽  
Assessment Tools ◽  
Geological Conditions ◽  
Rainfall Region ◽  
Semi Arid

<p>For many decades the problem of land degradation has been an issue in South Africa. This is mainly due to the high variability of the mostly semi-arid climatic conditions providing a challenging environmental setting. Strong population growth and resulting socio-economic pressure on land resources aggravate the situation. Thus, reaching a number of Sustainable Development Goals (SDGs), like achieving food security (#2), access to clean water (#6), and the sustainable use of terrestrial (#15) and marine (#14) resources represents a challenge.</p><p>In South Africa, land degradation has been linked to the terms veld degradation and soil degradation and has been addressed by numerous measures over the past decades. However, 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 the overarching goal of SALDi is to implement novel, adaptive, and sustainable tools for assessing land degradation in multi-use landscapes. Building upon the state of the art in land degradation assessments, the project aims to advance current methodologies 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), growing sources of in-situ data and advancements in modelling approaches.</p><p>SALDi focusses on six study sites representing a major climate gradient from the (humid) winter-rainfall region in the SW across the (semi-arid) year-round rainfall to the (very humid) summer-rainfall region in the NE. The sites cover also different geological conditions and different agricultural practices. These include commercial, rain-fed and irrigated cropland, free-range cattle and sheep farming as well as communal and subsistence farming. Protected areas within our study regions represent benchmark sites, providing a foundation for baseline trend scenarios, against which climate-driven ecosystem-service dynamics of multi-used landscapes (cropland, rangeland, forests) will be evaluated.</p><p>The aim of this presentation is to provide an overview of recent activities and advancements in the three thematic fields addressed by the project:</p><p>i) to develop an automated system for high temporal frequency (bi-weekly) and spatial resolution (10 to 30 m) change detection monitoring of ecosystem service dynamics,</p><p>ii) to 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,</p><p>iii) to advance current soil degradation process assessment tools for soil erosion.</p><p>A number of additional SALDi team member presentations will provide detailed information on current developments.</p>

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

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

<p>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.</p><p>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:</p><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><p>iii)    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.</p><p>The aim of this presentation is to introduce this new cooperative research project to the EGU Community and to seek new opportunities for collaboration.</p>

Earth Observation Strategies for degradation monitoring in South Africa with Sentinels – Results from the SPACES 2 SALDi-project 

2021 ◽  
Author(s):  
Christiane Schmullius ◽  
Marcel Urban ◽  
Kai Heckel ◽  
Hilma Sevelia Nghiyalwa ◽  
Andreas Hirner ◽  
...  
Keyword(s):  
South Africa ◽  
Time Series ◽  
Soil Moisture ◽  
Ecosystem Services ◽  
South African ◽  
Land Degradation ◽  
Ecosystem Service ◽  
Data Cube ◽  
Assessment Tools ◽  
Individual Development

<p>The project ‘South African Land Degradation Monitor (SALDi)’ contributes to the German-South African Science Program SPACES by addressing the dynamics and functioning of multi-use landscapes with respect to land use, land cover change, water fluxes, and implications for habitats and ecosystem services. Particularly, SALDi aims: i) to develop an automated system for high temporal (bi-weekly) and spatial resolution (10 to 30 m) change detection monitoring of ecosystem service dynamics, ii) to 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, iii) to advance current soil degradation process assessment tools as a limiting factor for ecosystem services. Protected areas (SANParks and other) within our six study regions represent benchmark sites, providing a foundation for baseline trend scenarios, against which climate-driven ecosystem service dynamics of multi-used landscape (cropland, rangeland, forests) are evaluated. Our study regions follow a climatic SW-NE transect: 1-Overberg, 2-Kai !Garib/Augrabies Falls, 3-Sol Plaatje/Kimberley, 4-Mantsopa/Ladybrand, 5-Bojanala Platinum/Pilanesberg, 6-Ehlanzeni /Mpumalanga.</p><p>We are utilizing Sentinel-1A/B C-Band VV/VH-SAR time series with a 10 m resolution. The revisit time is 12 days on average for South Africa. Pre-processing is done using pyroSAR, a Python framework for large-scale SAR-processing providing processing utilities in ESA’s Sentinel Application Platform (SNAP) as well as GAMMA Remote Sensing software. The first two analytical approaches for the evaluation of the Sentinel-1 time series to detect surface changes, are based on the recognition of irregularities in the radar backscatter or coherence dynamics. Sentinel-2A/B data were pre-processed to L2A and used to calculate a wide range of vegetation indices (e.g. NDVI, EVI, SAVI, REIP) using DLR’s Sen2Cor-processor. The time frame starts with the first Sentinel-1 and -2 acquisitions and continues. The analysis-ready data, that is, harmonized, standardized, interoperable, radiometrically and geometrically consistent data, is being ingested in the SALDi Data Cube. Algorithms and models for developing products such as land degradation indicators are being developed using Jypiter notebooks. SANSA in collaboration with SARAO (South African Radio Astronomy Observatory), is developing the open data cube Digital Earth South Africa (DESA) based on SPOT data. Other datasets from different sensors will be ingested at a later stage. SALDi’s Data Cube will be open access to make it available to the wider scientific community, and also for teaching and training purposes. The application/use of the individual development stages should be possible on the fly for the partners in South Africa. The SASSCAL platform shall be used for distribution of the finalised SALDi Data Cube.</p><p>This presentation demonstrates results from hyper-temporal Sentinel-1 and -2 timeseries concerning woody cover mapping and breakpoint analyses of the complex savanna systems, invasive slangbos (Seriphium plumosum) bush encroachment in grassland areas and regional soil moisture retrievals. Validation has been performed by cross-comparisons with VHR airborne DMC surface products, field trips and permanently installed soil moisture networks and interaction with local South African stakeholders.</p><p> </p>

Evaluating the role of soil physical properties on simulated land-atmosphere interactions over South Africa using coupled atmosphere-hydrological modeling

2021 ◽  
Author(s):  
Zhenyu Zhang ◽  
Patrick Laux ◽  
Joël Arnault ◽  
Jianhui Wei ◽  
Jussi Baade ◽  
...  
Keyword(s):  
South Africa ◽  
Physical Properties ◽  
Land Degradation ◽  
Land Surface ◽  
Soil Physical Properties ◽  
Near Surface ◽  
Soil Database ◽  
Global Soil ◽  
The Impact

<p>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.</p>

A Taxonomic Revision of the Othonna bulbosa Group (Asteraceae: Senecioneae: Othonninae)

2019 ◽  
Vol 104 (4) ◽  
pp. 515-562 ◽  
Author(s):  
Simon L. Magoswana ◽  
James S. Boatwright ◽  
Anthony R. Magee ◽  
John C. Manning
Keyword(s):  
South Africa ◽  
South African ◽  
Geographical Distribution ◽  
Taxonomic Revision ◽  
Cape Floristic Region ◽  
The South ◽  
Winter Rainfall ◽  
African Species ◽  
Taxonomic Treatment ◽  
Rainfall Region

Othonna L. (Asteraceae: Senecioneae: Othonninae) is a genus of some 120 species concentrated in the Greater Cape Floristic Region (GCFR) of South Africa, with a few species extending into southern Namibia, Angola, and Zimbabwe. The South African species of Othonna were last revised more than a century ago, and many species, particularly from the southern African winter rainfall region, remain poorly understood. This study focused on the geophytic species comprising the O. bulbosa group, distinguished by their tuberous rootstock and annual, leafy, aerial stems. A comprehensive taxonomic treatment is presented, including descriptions, complete nomenclature and typification, illustrations, and geographical distribution. Twenty-five species are recognized, of which four are newly described (O. lilacina Magoswana & J. C. Manning, O. nigromontana Magoswana & J. C. Manning, O. revoluta Magoswana & J. C. Manning, and O. sinuata Magoswana & J. C. Manning), and 18 names are reduced to synonymy. The species differ in habit, shape and incision of foliage, capitulum type (radiate vs. disciform), number of involucral bracts, pappus length, and cypselae (myxogenic vs. nonmyxogenic). We place the species into four morphologically diagnosable series (series Heterophyllae Magoswana & J. C. Manning, series Disciformes Magoswana & J. C. Manning, series Perfoliatae Magoswana & J. C. Manning, and series Undulosae Magoswana & J. C. Manning) based on habit and capitulum type.

RECONSTRUCTING RECENT LAND DEGRADATION IN THE SEMI-ARID KAROO OF SOUTH AFRICA: A PALAEOECOLOGICAL STUDY AT COMPASSBERG, EASTERN CAPE

2012 ◽  
Vol 23 (6) ◽  
pp. 523-533 ◽  
Author(s):  
T. M. Mighall ◽  
I. D. L. Foster ◽  
K. M. Rowntree ◽  
J. Boardman
Keyword(s):  
South Africa ◽  
Land Degradation ◽  
Eastern Cape ◽  
Semi Arid

scholarly journals Water quality modelling of an impacted semi-arid catchment using flow data from the WEAP model

2018 ◽  
Vol 377 ◽  
pp. 25-33 ◽  
Author(s):  
Andrew R. Slaughter ◽  
Sukhmani K. Mantel
Keyword(s):  
South Africa ◽  
Water Quality ◽  
South African ◽  
Water Resources Management ◽  
Nutrient Concentrations ◽  
Water Quality Modelling ◽  
Weap Model ◽  
Resources Management ◽  
Systems Model ◽  
Semi Arid

Abstract. The continuous decline in water quality in many regions is forcing a shift from quantity-based water resources management to a greater emphasis on water quality management. Water quality models can act as invaluable tools as they facilitate a conceptual understanding of processes affecting water quality and can be used to investigate the water quality consequences of management scenarios. In South Africa, the Water Quality Systems Assessment Model (WQSAM) was developed as a management-focussed water quality model that is relatively simple to be able to utilise the small amount of available observed data. Importantly, WQSAM explicitly links to systems (yield) models routinely used in water resources management in South Africa by using their flow output to drive water quality simulations. Although WQSAM has been shown to be able to represent the variability of water quality in South African rivers, its focus on management from a South African perspective limits its use to within southern African regions for which specific systems model setups exist. Facilitating the use of WQSAM within catchments outside of southern Africa and within catchments for which these systems model setups to not exist would require WQSAM to be able to link to a simple-to-use and internationally-applied systems model. One such systems model is the Water Evaluation and Planning (WEAP) model, which incorporates a rainfall-runoff component (natural hydrology), and reservoir storage, return flows and abstractions (systems modelling), but within which water quality modelling facilities are rudimentary. The aims of the current study were therefore to: (1) adapt the WQSAM model to be able to use as input the flow outputs of the WEAP model and; (2) provide an initial assessment of how successful this linkage was by application of the WEAP and WQSAM models to the Buffalo River for historical conditions; a small, semi-arid and impacted catchment in the Eastern Cape of South Africa. The simulations of the two models were compared to the available observed data, with the initial focus within WQSAM on a simulation of instream total dissolved solids (TDS) and nutrient concentrations. The WEAP model was able to adequately simulate flow in the Buffalo River catchment, with consideration of human inputs and outputs. WQSAM was adapted to successfully take as input the flow output of the WEAP model, and the simulations of nutrients by WQSAM provided a good representation of the variability of observed nutrient concentrations in the catchment. This study showed that the WQSAM model is able to accept flow inputs from the WEAP model, and that this approach is able to provide satisfactory estimates of both flow and water quality for a small, semi-arid and impacted catchment. It is hoped that this research will encourage the application of WQSAM to an increased number of catchments within southern Africa and beyond.

Development of earth observation data cubes for monitoring land degradation processes in South Africa

2021 ◽  
Author(s):  
Insa Otte ◽  
Nosiseko Mashiyi ◽  
Pawel Kluter ◽  
Steven Hill ◽  
Andreas Hirner ◽  
...  
Keyword(s):  
South Africa ◽  
Land Use ◽  
Ecosystem Services ◽  
Land Use Change ◽  
South African ◽  
Land Degradation ◽  
Earth Observation ◽  
Observation Data ◽  
Data Cubes ◽  
Earth Observation Data

<p>Global biodiversity and ecosystem services are under high pressure of human impact. Although avoiding, reducing and reversing the impacts of human activities on ecosystems should be an urgent priority, the loss of biodiversity continues. One of the main drivers of biodiversity loss is land use change and land degradation. In South Africa land degradation has a long history and is of great concern. The SPACES II project SALDi (South African Land Degradation Monitor) aims for developing new, adaptive and sustainable tools for assessing land degradation by addressing the dynamics and functioning of multi-use landscapes with respect to land use change and ecosystem services. SPACES II is a German-South African “Science Partnerships for the Adaptation to Complex Earth System Processes”. Within SALDi ready-to-use earth observation (EO) data cubes are developed. EO data cubes are useful and effective tools using earth observations to deliver decision-ready products. By accessing, storing and processing of remote sensing products and time-series in data cubes, the efficient monitoring of land degradation can therefore be enabled. The SALDi data cubes from optical and radar satellite data include all necessary pre-processing steps and are generated to monitor vegetation dynamics of five years for six focus areas. Intra- and interannual variability in both, a high spatial and temporal resolution will be accounted to monitor land degradation. Therefore, spatial high resolution earth observation data from 2016 to 2021 from Sentinel-1 (C-Band radar) and Sentinel-2 (multispectral) will be integrated in the SALDi data cube for six research areas of 100 x 100 km. Additionally, a number of vegetation indices will be implemented to account for explicit land degradation and vegetation monitoring. Spatially explicit query tools will enable users of the system to focus on specific areas, like hydrological catchments or blocks of fields.</p>

Assessing the interactions of atmosphere and land surface over South Africa with convective-permitting coupled atmospheric-hydrological modeling

2020 ◽  
Author(s):  
Zhenyu Zhang ◽  
Joel Arnault ◽  
Patrick Laux ◽  
Jussi Baade ◽  
Harald Kunstmann
Keyword(s):  
South Africa ◽  
Energy Budget ◽  
Land Degradation ◽  
Land Surface ◽  
Hydrological Modeling ◽  
Soil Depth ◽  
Atmospheric Modeling ◽  
Subsurface Water ◽  
Earth System ◽  
Potential Productivity

<p>Land degradation, as a major issue in South Africa, undermines water resources and land potential productivity, and threatens the ecosystem biodiversity and human activities. In the scope of accurately assessing the land degradation processes in multi-use landscapes, the atmosphere-land surface relations and the dynamics of land surface state variabilities need to be addressed in a detail. This requires Earth System modeling approaches jointly considering high-resolution atmospheric modeling, land surface and hydrological modeling frameworks. This study investigates the atmosphere-land interactions and land surface water-energy budget for South Africa using the Earth System Model WRF-Hydro. WRF-Hydro is the fully coupled atmosphere-land surface-hydrology modeling system, which enhances the Weather Research and Forecasting model with the overland and subsurface water routing processes. In the WRF-Hydro modeling setup, the atmospheric part is configured in a convection-permitting spatial resolution at 4 km, with horizontal grids of 650 × 500 points, covering area of Southern Africa. In the land surface, the gridded hydrological processes are routed on a 400 m fine hydrological subgrid, within a soil depth of 2 m. In this study, we perform the coupled simulation for the year of 2010 and show the validation of modeling results with multiple reference datasets. The water-energy budget in the land surface from coupled WRF-Hydro simulation is assessed on 22 primary hydrological drainage regions. Model results show that coupled atmospheric-hydrological modeling is able to represent the regional water and energy budget, and to resolve atmosphere-land surface interactions. This allows the further usage of the coupled atmospheric-hydrological modeling in the context of land degradation studies, e.g. under different land-use scenarios.</p>

I.—The Geological History of South Africa

1906 ◽  
Vol 3 (3) ◽  
pp. 97-104 ◽  
Author(s):  
F. H. Hatch
Keyword(s):  
South Africa ◽  
South African ◽  
Coastal Area ◽  
Land Surface ◽  
Geological History ◽  
Physical Conditions ◽  
History Of ◽  
The Subject ◽  
History Of The South ◽  
Broad Outline

The subject of this address is a brief acount of the succession, thickness, and geological history of the South African, and more especially of the Transvaal, formations. The information necessary for such an account is of course very incomplete, but in broad outline the succession is now known, and some speculation as to the physical conditions that prevailed during the building up of the region may perhaps be permitted. I propose to deal with the period of the geological history of this country that came to an end with the close of Karroo times. The Karroo period ends with the Stormberg rocks (Rhæitic), and since that time South Africa has, with the exception of a small coastal area, been a land surface, and the rocks have consequently been exposed uninterruptedly to the forces of denudation.

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