This website is presented solely for educational purposes and cannot be reproduced or transmitted either electronically, mechanically or by any form without the permission of the South African National Space Agency. The author and publisher are not offering it as legal, accounting, or other professional services advice. While best efforts have been made in preparing this website, the author and publisher make no representations or warranties of any kind and assume no liabilities of any kind with respect to the accuracy or completeness of the contents and specifically disclaim any implied warranties of merchantability or fitness of use for a particular purpose. Neither the author nor the publisher shall be held liable or responsible to any person or entity with respect to any loss or incidental or consequential damages caused, or alleged to have been caused, directly or indirectly, by the information or programmes contained herein.
Agency: South African National Space Agency (SANSA) RAD Manager: Dr. Paida Mangara Project Manager: Mr. Phila Sibandze Website developer: Mr. Hugo De Lemos Contributors: Hugo De Lemos, Willard Mapurisa, Naledzani Mudau, Willem Vorster, Thomas Tsoeleng, Morwapula Mashalane, Thando Oliphant, Mahlatse Kganyago, Maite Machipi, Wongama Tengela, Johnny Rizos, Dan Matsapola, Nicky Knox, Ndleleni Boyilane, Carole Liddy and Mamphago Molewa.
POST-FLOOD AND FLOOD RISK ANALYSIS
South African Flood Inundation Layer
The potential flood map is a product indicating the water level above the river channel (fig. 2). The product has been developed for three water levels of 1, 3 and 5 metres above the river channel.
The product can be used for different applications such as:
• Identifying areas vulnerable to flooding.
• Identifying infrastructure and other environmental resources that are situated within the flood risk zones.
• Identify flood line and developing flood plain maps.
• Providing valuable information for planning purposes, such as town planning and infrastructure development.
• Water management and irrigation planning.
• Developing hydrological and disaster risk reduction models for early warning.
The potential flood map was developed from the Height Above Nearest Drainage (HAND) product which is a hydrologically relevant elevation data based on topography. The difference between the HAND product and the digital elevation model (DEM) is that the elevation in a DEM is calculated from the sea level which is zero and increases further inland. In contrast, the HAND product is calculated from the river channel which has a value of zero at the river channel as demonstrated in figure 1.
Figure 1: Profile comparison between SRTM DEM and HAND.
Figure 2: South African Flood Inundation Layer.
Natural disasters are catastrophic events which result from natural processes of the earth affecting human livelihood and at times claiming lives. Remote sensing is significant in disaster management to prepare, recover and respond to disasters such as floods. Remote sensing makes it possible to do a post analysis assessment of the area affected after the floods by identifying the affected infrastructure and the extent of the flooded area.
Flooded areas within and around Chokwe, the satellite image shows how the road and railway infrastructure were affected. Such information is critical in identifying alternative routes during rescue and recovery operations.