01/16 Geo-Ecological Baseline Studies in Kruger National Park using the RIEGL VZ-1000

The Kruger National Park (KNP) in South Africa covers 20 000 km² and is Africa’s oldest national park. It has preserved diverse wildlife and a pristine savannah ecosystem for over a century now. The rolling landscape is covered by unique vegetation with varying density of woody vegetation, grasses and wildflowers. The Kruger National Park is particularly suited for geo-ecological studies, due to the fact that the area was set aside for wildlife conservation over 100 years ago and has never experienced agricultural development or the associated disturbance of soils and vegetation. It is an exceptionally well documented area, providing a number of datasets relevant to s environmental change studies, such as Digital Elevation Models (DEMs), geology, soils, vegetation and vegetation change, fire records, climatological records, and aerial photos.

In the framework of an ongoing research collaboration with South African National Parks (SANParks) Scientific Services about savannah landscape dynamics, the Department of Geography at the Friedrich-Schiller-University Jena (Germany) is utilizing a RIEGL VZ-1000 to acquire data to create high resolution surface models.

One project is investigating long-term erosion in KNP to provide benchmarks on natural erosion rates under the present climatic conditions. This includes the survey of dried up reservoirs, surfaces prone to sheet and gully erosion, and sandy river beds (see photo). Due to its high resolution, precision and speed, the VZ-1000 provides a unique tool to document the present status of these features in very high resolution DEM’s. The RISCAN PRO software is used to merge the point clouds acquired from up to 20 scan positions and to separate returns from the terrain and other targets, such as vegetation or even wildlife. Revisiting and rescanning the study sites after the next major storm will provide the opportunity to monitor surface changes and to quantify current erosion rates.

A second project is investigating the vegetation structure and dynamics in the vicinity of the Skukuza Flux Tower. Here, the RIEGL VZ-1000 is used to document the current structure of the vegetation cover and to estimate above ground biomass to support carbon studies. Matching high resolution point clouds with concurrent satellite imagery helps to better relate the information from the rather low resolution satellite imagery to the surface structure and properties. Combining the present surveys with a time series of satellite imagery will eventually provide the opportunity to quantify the changes in above ground biomass over the past decades. To capture the 37 ha large area and to minimize shadow effects induced by the vegetation, we acquired data from 30 scan positions. Moving by foot from one site to the other, the backpack proved to be a valuable accessory for the RIEGL VZ-1000.

The initial data acquisition with the RIEGL VZ-1000 was conducted in September and October 2015. Air temperatures reached well above 40 °C in the shade and it was inevitable to fully expose the scanner to the sun. Even under these harsh environmental conditions, the RIEGL VZ-1000 acquired reliable data. Some heat related issues with the external battery were solved by cooling down the battery while driving back to the camp in the air-conditioned bakkie (off-road vehicle) and recharging it overnight in an air-conditioned room.