Construction of Water Surface Topography Using LIDAR Data

Measurements of water surface topography are important for hydraulic structures, operation of hydropower plants as well as in the determination of water surface profiles in rivers, especially in the event of high waters We therefore investigated the conditions at a confluence of two supercritical flows, where distinctly three-dimensional flow conditions of standing waves form, as well as an unsteady structure of the water flow in transversal and longitudinal directions Due to the fast water surface dynamics and the phenomenon of foamed or two-phase flow, the conventional measurement methods typically used in hydro engineering are not suitable for capturing complex water surface topography with high temporal and spatial resolution. Hence we wanted to verify the appropriateness of the laser scanning method for water surface topography measurements. This measurement method, which is considered less suitable or even useless for measurements of water body surfaces, was, coupled with an innovative approach, successfully used for water surface measurements of dynamic, turbulent, two-phase water flow. The acquisition of a point cloud with high temporal and spatial resolution allows for the construction of topography of intensive waving which will also enable a topology analysis based on a phenomenological analysis of the relations between integral parameters of water flows and standing wave characteristics at the confluence.