Learning to use remote sensing to establish woody plant encroachment in the savanna biome

By Tiffany Aldworth, PhD Hydrology Student, SAEON Grasslands-Forests-Wetlands Node and University of KwaZulu-Natal Tweet

Tiffany's PhD research focuses on understanding the impacts of woody plant encroachment on freshwater resources in South Africa’s savanna biome The four-day training course featured theory lessons and corresponding practical tutorials using Sentinel-1 data

The two main types of satellite data used in remote sensing to produce images of the earth's surface include optical and radar.

Optical satellites use visible and infrared sensors to detect the solar radiation reflected from targets on the ground, whereas radar satellites emit microwaves and calculate the time they take to return to the sensor after reflecting from targets.

Optical remote sensing is more commonly used but radar remote sensing is more continuous, has an inherently higher information content and a higher resolution. Its biggest advantage is that it is not affected by lighting or weather conditions, allowing radar satellites to operate at night and during cloudy conditions.

First EMSAfrica Summer School

From 23 to 26 September, I attended the first EMSAfrica Summer School on the basics and applications of synthetic aperture radar (SAR) remote sensing for environmental monitoring.

The summer school took place at the Wits Rural Facility in Acornhoek, Mpumalanga. It consisted of a four-day hands-on training course which featured a mixture of theory lessons and corresponding practical tutorials using Sentinel-1 data.

The coordinating institution was the Department for Earth Observation, Friedrich-Schiller University in Jena, Germany, through the SPACES projects, EMSAfrica (Ecosystem Management Support for Climate Change in southern Africa) and SALDi (South African Land Degradation Monitor).

The summer school was funded by the German Federal Ministry of Education and Research (BMBF). Thirteen students, researchers and technicians from several southern African countries, including South Africa, Swaziland and Botswana, attended.

My PhD research focuses on understanding the impacts of woody plant encroachment on freshwater resources in South Africa’s savanna biome. The research, which is being conducted in a private game reserve in Phalaborwa in the Limpopo province, is primarily field based but I also plan to use remote sensing to establish the extent and rate of woody plant encroachment in the area and to extract information to compare with field observations and upscale them to catchment and national scales.

The summer school equipped me with skills which will certainly benefit my research. Overall it was a great experience, where I learnt a lot and made many new connections. Many thanks to the course organiser, Dr Christian Berger from the Friedrich-Schiller University, his team and the BMBF. 

The course was also attended by SAEON MSc students Keletso Moilwe and Lungile Khuzwayo, whose projects focused on mapping invasive alien trees in grasslands and fynbos respectively. SAEON's Dr Gregor Feig and Dr Jasper Slingsby are collaborators on the EMSAfrica project.

Thirteen students, researchers and technicians from several southern African countries attended the summer school