Measuring and analysing of flood waves in Rhine river; an application of laser altimetry

Abstract

The Survey Department of Rijkswaterstaat in The Netherlands makes intensive use of laser altimetry for topographic measurements. A new application is to measure the water level, during flood waves in rivers. As the laser signal reflects differently on water compared to land, a high point density was used. This large data set gives spatial detailed information about the flood wave, the along — and across — track slope of the river and information to derive the water resistance on different vegetation areas.

The laser data gives a high detail of information, and the breakwaters in the river are clearly visible. Computing the different roughness coefficient with laser and additional discharge measurements, will be an important improvement for water management. These roughness values will optimise the hydraulic models used to predict the water movement in rivers.

In this paper the laser altimetry technique is being explained, and some examples are shown. Then the Rhine project will be discussed, and a first attempt to give an indication of the roughness coefficient are shown.