This project served two purposes: 1) generation of reliable, accurate and fit for purpose bathymetric & topographic data of the Msimbazi River and its floodplains for riverine flooding related detailed studies, and 2) rigorous comparison of DTM generation by UAV Photogrammetry and UAV LiDAR. Traditionally LiDAR aerial acquisition methods for obtaining DTMs are done by planes. With the development of equipment, the LiDAR scanners are getting smaller and lighter, and UAVs can fly longer and can carry more weight, enabling to mount LiDAR scanner to drones. This potentially provides significant cost savings compared to both traditional LiDAR and field surveying methods. A meticulous comparison for the Sub-Saharan African context was however lacking. This study recommends on when to use which surveying methods with respect to project area size, land-use/vegetation cover and challenges like import of equipment.
An integral survey campaign was undertaken. In order to achieve the 2 objectives, the following tasks have been executed:
- Setting out Ground Control Points and Benchmarks
- RTK-GNSS River bathymetry profile measurements
- UAV (Drone) LiDAR Survey and UAV (Drone) Photogrammetry Survey
- Water level and salinity measurements
The results of the 2 UAV topographic survey methods have been compared through advanced GIS/ spatial analysis. Vegetation types have been mapped and metrics have been assessed for the respective vegetation classes accordingly.