Remote sensing

Remote sensing – the acquisition of information about the Earth's surface through satellite, airborne, or drone-based sensors – has become an indispensable tool in water resource science. It enables the monitoring of rainfall, surface water extent, vegetation cover, soil moisture, land use change, flood inundation, erosion, water quality, and groundwater storage anomalies across large and often inaccessible areas, at temporal frequencies and spatial scales that would be impossible to achieve through ground-based monitoring alone. South Africa has a well-established remote sensing research community, supported by SANSA, CSIR, and numerous universities, and benefits from access to a growing range of free and commercial satellite data products.

The resources below provide access to South African national imagery archives, free global satellite data platforms, and commercial high-resolution products relevant to water resource research and management.

South African National Data

National Geo-spatial Information (NGI) – DALRRD South Africa's national mapping authority, providing access to aerial photography, orthophoto maps, digital elevation models, and other geo-spatial products covering the entire country. NGI also offers specialist remote sensing services.

SANSA Earth Observation The South African National Space Agency's earth observation division, providing satellite imagery, data processing services, and value-added products derived from a range of sensors. SANSA operates a ground receiving station at Hartebeesthoek and archives satellite data relevant to southern Africa.

Free Global Satellite Platforms

Google Earth Engine A cloud-based platform providing access to a vast catalogue of satellite imagery – including MODIS, Landsat, and Sentinel datasets with powerful analytical tools for large-scale geospatial analysis. The recommended primary access point for satellite data for water-related research. A beginner tutorial is available here.

Copernicus Open Access Hub (ESA) The European Space Agency's free data portal for Sentinel satellite imagery, including Sentinel-1 (SAR, useful for flood mapping), Sentinel-2 (multispectral, useful for land cover and water quality), and Sentinel-3 (ocean and land colour)

NASA Earthdata A comprehensive portal for accessing NASA's earth observation datasets, including MODIS, Landsat, VIIRS, and GRACE gravity-based groundwater anomaly data

USGS Earth Explorer The US Geological Survey's data portal providing access to Landsat imagery archives dating back to the 1970s – an invaluable resource for long-term land cover and water body change analysis

Global Surface Water Explorer (JRC / Google) A satellite-derived dataset mapping the location and temporal dynamics of surface water globally since 1984, including seasonal and permanent water bodies, water occurrence, and change – directly relevant to dam monitoring, wetland mapping, and flood analysis.

CHIRPS Rainfall Estimates Climate Hazards Group InfraRed Precipitation with Station data – a high-resolution satellite-derived rainfall dataset widely used in South African hydrological and agricultural studies

NASA GRACE Data Analysis Tool Satellite-based tool using gravitational data from the GRACE and GRACE-FO missions to detect changes in terrestrial water storage, including groundwater depletion and recharge, at regional scale

MODIS Land Products (NASA) A suite of freely available moderate-resolution satellite products including vegetation indices (NDVI, EVI), land surface temperature, fire, and snow cover – widely used in South African water and ecology research

Commercial High-Resolution Products

The following commercial satellite systems provide very high-resolution imagery suitable for detailed site-level analysis, infrastructure assessment, and precision monitoring. Access is subject to commercial licensing:

IKONOS – up to 0.82 m resolution, multispectral and panchromatic
RapidEye – 5 m resolution with red-edge band, suitable for vegetation and agricultural analysis
WorldView – up to 0.31 m resolution, the highest commercially available
ZY-3 – Chinese satellite with 2.1 m panchromatic resolution
QuickBird – up to 0.61 m resolution, panchromatic and multispectral
GF-1/2 (Gaofen) – Chinese high-resolution satellites with 1–2 m resolution

For commercial imagery procurement in South Africa, contact SANSA Earth Observation or specialist resellers such as Esri South Africa and Pinpoint.

Learning Resources

NASA ARSET – Applied Remote Sensing Training Free online training courses from NASA covering remote sensing applications in hydrology, water quality, flood monitoring, land cover, and agriculture – highly recommended for researchers and practitioners new to satellite data

ESA Training Courses Free training materials and courses from the European Space Agency on the use of Copernicus and Sentinel data for environmental monitoring