The Isimangaliso Wetland (IW) in KwaZulu-Natal Province of South Africa has a variety of wetlands that contribute valuable ecosystem services to a notable number of people, the natural species ...habitat and tourism interests. Wetlands are epoch-making reproducing and nourishing zones for wildlife and give shelters and protection for sea creatures. As with any natural habitat, wetlands are important in supporting species diversity as well as providing the climate moderating element. This study aimed at appraising the spatial pattern of the Isimangaliso Wetland, the potential determinants and effects of the wetland depletion between 1987 and 2017 using remote sensing and GIS approach. Landsat Thematic Mapper (TM) images acquired for 1987, 1997, 2007 and Landsat 8 Thermal Infrared Sensor (TIRS) and Operational Land Imager (OLI) imagery for 2017 was acquired from the archives of United States Geological Survey (USGS) for the analysis using ArcGIS 10.2. The Normalized Difference Water Index (NDWI) analyses between 1987 and 2017 successfully revealed the significant depletion of the water surrounding IW area which might be as a result of natural or human activities which may include climate change, built-up areas and agricultural activities. In 1987 and 2017, the results showed that wetland extent was 655.416 Km2 and 429.489 Km2 respectively which connotes that IW has witnessed significant changes during the study period over the area. It was also revealed that the other land features (vegetation, built-up, open surface and rocky surface) over the area increased from 2149.911 Km2 to 2375.838 Km2 in 1987 and 2017 respectively. The overall classification accuracy of 97.55% and Kappa coefficient of 0.941. This wetland depletion might have a significant impact on biodiversity including human and animals as well as plants thus diminishing its world heritage status. Consequently, this natural gift needs to be conserved to create a livable environment for wetland animals in order to moderate local climate as well as preserve human wellness and protection by reducing flood disaster and maintaining efficient water quantity and quality in the area.
The famous R.E.M. song laments ‘It’s the end of the world as we know it, I had some time alone, I feel fine…’. Many South Africans would agree that COVID-19 signals the end of the world (or business) ...as we know it, and through the lockdown we have certainly had some time alone. But contrary to the lyrics, all may not be fine, especially for South Africa’s scientific community.
Located in the sub-Antarctic, Marion Island (46° 54′ S, 37° 45′ E) has a distinct periglacial environment that is sensitive to climate change. Diurnal soil frost is the most important geomorphic ...process occurring on the island and this paper aims to understand the synoptic weather circulation pattern associated with summer soil frost occurrence in a sub-Antarctic environment. Preliminary results from automated microclimate measurements in the interior of Marion Island show that summer soil frost is dependent on Antarctic air mass circulation. This occurs exclusively during post-cyclonic airflow after the passage of a cold front connected to a mid-latitudinal cyclone and subsequent ridging in of the South Atlantic Anticyclone behind the cold front, or when a series of low pressure systems passes over the island. The duration and intensity of soil frost cycles are dependent on the duration of post-cyclonic Antarctic air mass circulation. Summer soil frost on Marion Island is driven by a complex interaction between the latitudinal position of the passing cyclone, the latitudinal position of the ridging anticyclone as well as the trajectory of the air mass circulation. The data suggest that predicted trends in synoptic climate change in the sub-Antarctic may lead to non-linear responses in soil frost dynamics.
Researchers of projects at the sub-Antarctic Prince Edward Islands are increasingly considering geospatial data as an essential component in answering scientific questions. A need exists for ...high-resolution geospatial data in both multi- and transdisciplinary research to better analyse fine-scale biotic–abiotic interactions of the Islands’ landscape and ecosystems within the context of climate change and the impacts of invasive species. However, much of the geospatial data that currently exist have limitations in spatial coverage and/or resolution, are outdated, or are not readily available. To address these issues, we present an online geospatial database for the Prince Edward Islands (both islands) produced from a high-resolution digital surface model and satellite imagery. This database contains vector files, raster data sets, and maps of topographical and hydrological parameters. It is freely available to download from Figshare – an open access data repository. We encourage the South African polar science community to make use of similar platforms for improved data sharing practices.Significance: • A topographical and hydrological geospatial database – produced from a 1 m x 1 m digital surface model of the Prince Edward Islands – is provided. • These fine-scale geospatial data allow for a more comprehensive assessment of biotic–abiotic interactions at an island scale. • Also included are locality maps specifying place names and established long-term marine mammal monitoring beaches and coastal zones for improved cross-referencing. • The dataset is downloadable from an open access data repository and intended to promote open science and data sharing practices.
Since the discovery of glacial features on sub-Antarctic Marion Island, the character and extent of a historic glacial period have remained an important research focus for earth science ...investigations. Previous glacial reconstructions were limited to mostly pre-GPS field observations and pre-digital mapping through a Geographic Information System. With the aid of GPS field mapping, high-resolution satellite imagery and a digital surface model with a 1 × 1 m cell resolution, this paper provides a comprehensive, geo-rectified spatial geodatabase and map of Marion Island's glacial geomorphology. The geodatabase includes an inventory of glacial erosional (e.g. striations) and depositional (e.g. moraines) features compiled from existing records as well as new features mapped from recent field observations. The final map and the geodatabase, which is downloadable as ESRI layer-package files, will aid future field investigations and modelling applications to understand Marion Island's Quaternary landscape evolution and post-glacial ecological succession.
CLIGEN is a stochastic weather generator that creates statistically representative timeseries of daily and sub-daily point-scale weather variables from observed monthly statistics and other ...parameters. CLIGEN precipitation timeseries are used as climate input for various risk-assessment modelling applications as an alternative to observe long-term, high temporal resolution records. Here, we queried gridded global climate datasets (TerraClimate, ERA5, GPM-IMERG, and GLDAS) to estimate various 20-year climate statistics and obtain complete CLIGEN input parameter sets with coverage of the African and South American continents at 0.25 arc degree resolution. The estimation of CLIGEN precipitation parameters was informed by a ground-based dataset of >10,000 locations worldwide. The ground observations provided target values to fit regression models that downscale CLIGEN precipitation input parameters. Aside from precipitation parameters, CLIGEN's parameters for temperature, solar radiation, etc. were in most cases directly calculated according to the original global datasets. Cross-validation for estimated precipitation parameters quantified errors that resulted from applying the estimation approach in a predictive fashion. Based on all training data, the RMSE was 2.23 mm for the estimated monthly average single-event accumulation and 4.70 mm/hr for monthly maximum 30-min intensity. This dataset facilitates exploration of hydrological and soil erosional hypotheses across Africa and South America.
Here, we present and release the Global Rainfall Erosivity Database (GloREDa), a multi-source platform containing rainfall erosivity values for almost 4000 stations globally. The database was ...compiled through a global collaboration between a network of researchers, meteorological services and environmental organisations from 65 countries. GloREDa is the first open access database of rainfall erosivity (R-factor) based on hourly and sub-hourly rainfall records at a global scale. This database is now stored and accessible for download in the long-term European Soil Data Centre (ESDAC) repository of the European Commission's Joint Research Centre. This will ensure the further development of the database with insertions of new records, maintenance of the data and provision of a helpdesk.
In addition to the annual erosivity data, this release also includes the mean monthly erosivity data for 94% of the GloREDa stations. Based on these mean monthly R-factor values, we predict the global monthly erosivity datasets at 1 km resolution using the ensemble machine learning approach (ML) as implemented in the mlr package for R. The produced monthly raster data (GeoTIFF format) may be useful for soil erosion prediction modelling, sediment distribution analysis, climate change predictions, flood, and natural disaster assessments and can be valuable inputs for Land and Earth Systems modelling.
This paper presents the heavy metal content in river water, sediment and bedrock in the karst area of the Pearl River Basin in China to evaluate the long-term impact of natural weathering and mining ...on the ecological environment. The results show that Cd and As is 2–3 times more enriched within the carbonate bedrock of the Pearl River Basin compared to the upper continental crust (UCC), which is indicative of high geological background values. Within the river water of the upper reaches of the Diaojiang River (a tributary of the Pearl River), which flows through the Dachang super-large orefield, Zn, As, Cd and Sb exceeds the environmental quality standards for surface water (WQS) by more than an order of magnitude. Among these, Zn and Cd sharply decreases to within the WQS in the lower reaches of the river, but the content of As and Sb in the estuary is still several times higher than the WQS. Cd in the sediments of the small carbonate watersheds and in the mainstream of the Pearl River only present a low-moderate ecological risk. In contrast, severe heavy metal pollution of the sediments of the Diaojiang River Basin is observed. Even in the lower reaches, remote from the mining area, the content of Pb, Zn, As and Cd in the sediments is still two orders of magnitude higher than the soil background values. The content of both Cd and As presents a very high ecological risk, indicating that under the cumulative effect of high geological background values and mining, full restoration of the ecological environment in the Diaojiang River Basin is a complex and long-term process.
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•The carbonate bedrock in southwest China has a high background value of Cd and As.•Small carbonate watershed without mining presents a certain ecological risk of Cd.•Metals pollution in upper Diaojiang River water has slight effect on downstream.•The ecological risk of metals in most of Diaojiang River sediments is very high.•The Pearl River shows the impact of human activity under high geologic background.
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