Use of high resolution LIDAR bathymetry data for the analysis of bed morphology in Alpine rivers

Katharina Baumgartner
Supervising board member: Markus Aufleger

Funding

Autonome Provinz Bozen-Südtirol - Provincia autonoma di Bolzano - Alto Adige;
3rd competition  for projects in the field of scientific research (WB2014)

Project Overview

Full geometrical and realistic topographic information about the riverbed is necessary for characterizing morphological structures in river systems and understanding river processes. Classical terrestrial cross-section surveys are increasingly supplemented or replaced by new remote sensing technologies and data processing methods. The technology of airborne LiDAR bathymetry (ALB) scanning allows the reliable and fast data acquisition of complex morphological structures with a very high resolution. Even in inaccessible alpine areas, this survey is feasible. A water-penetrating laser system uses the green region of the electromagnetic spectrum (wavelength = 532 nm) to record the ‘underwater topography’ to identify significant morphological structures in river systems. The point cloud density can be up to 50 points/m². A big benefit is the detection of the water surface which can be used for hydrodynamic modelling.

This work addresses the application of high-resolution LiDAR bathymetry data regarding river morphological changes of the river Mareit/Mareta in South Tyrol, Italy. It is part of the research project FHARMOR – Fish Habitat in Alpine Rivers: Integrating Monitoring, Modelling and Remote Sensing, which is dedicated to improve state-of-the-art habitat simulation and evaluation methodologies.

The project basically tries to use the advantages of the periodical high resolution LiDAR data to identify significant morphodynamic processes in alpine rivers. Further objectives are to identify uncertainties in bed-load transport modeling by using the ALB data and find advantages to evaluate river morphological changes in alpine rivers, like self-forming processes. Within the project an important step is the data processing of the LiDAR data, which includes the field survey, data control, post processing and georeferencing. A good bathymetry resolution is necessary for the morphodynamic modeling, which will be done with multi-fractioned simulation models. In addition to the morphodynamic modeling, the application of habitat models should assess the spatial variation of fish habitat over a time period. The study results remain to demonstrate the potential of new survey techniques in combination with morphodynamic models and improve habitat assessments.