Summary:

One of the important problems of hydraulic modeling is the appropriate representation of the geometry of the main river channel and valley. In the case of two-dimensional models, the main source of spatial information is data obtained by laser scanning (ALS). In spite of its generally high precision in the valley, the result for main riverbed doesn't correspond to the reality, due to the data acquisition process. During the process, laser beam is not able to penetrate the water, most of the beam is absorbed by the water and there is either no return signal or it is very weak and distorted. It is therefore necessary to generate the channel bathymetry data by conducting the interpolation technics on the data collected by the field survey. In the case of one-dimensional models or quasi-two-dimensional the field measurements are the main source of geometric data, but due to high labor costs, the measurements of the cross-sections are usually performed at large intervals. Sparse cross-section data lead to instability in the models, and also in the case of meandering rivers, portion of the discharge may be omitted or doubled. Solution to the problem is a densification of the cross-sections data inserted in to the model. Additional spatial data for the terrain can be derived from the digital elevation model (DEM) and data for the river channel needs to be interpolated from measured cross-sections. The main goal of this paper is to present methods of the channel bathymetry data interpolation and to highlight the advantages and the disadvantages of the assessed technics. Described interpolation technics are carried out either in ArcGIS or MIKE 11 applications.