Materials, Methods & Technologies, Volume 7, 2013

Streszczenie: During the operation of the water reservoirs in common conditions there occur the processes of the siltation as the result of the erosion in the watershed and also the processes of sediment displacement within the reservoir or sediment escape out of the reservoir as the result of the inflowing water during the floods or higher water discharges during the spring snowmelt. These processes are forming the shape of the water reservoir and this process affects the depths of water and total amount of stored water. The changes of the topography of smaller water reservoirs are not monitored periodically or occasionally and the methodology for the measuring is not made. For the larger reservoirs there is used the method of periodical measuring of the reservoir profiles as the cross-sections of the reservoir bottom. The comparison of the identical profiles is then used for evaluation of the siltation processes and calculation of the water capacity and sediment quantity difference during the revised time period. The method works with the depth measuring (echo sounding, level staves, calibrated lead line) and measuring of the distance of depth measuring in profiles. The goal of this paper is to assess the new method of monitoring of the reservoir topography with non-contact system of sonar and GPS receiver, which measures and generates the field of points with known coordinates at the bottom. These points can be used in GIS software for the creation of the TIN model that represents the reservoir bottom shape. The assessment of this method is done as the assessment of the accuracy of the created TIN model. This is done as the comparison of the geodetically measured elevation of points and elevation of points extracted from TIN model. The method was tested at the swimming pool, where steady and mostly plain bottom can be measured with geodesy tool – GPS measuring and compared with the TIN model created from data collected with non-contact measurement with GPS and sonar during the sail with small vessel. The comparison of the modeled elevation and the real bottom elevation offers the evaluation of the accuracy of the method. The results lead to conclusion that modeled elevations (calculated from data of TIN model created from the non-contact measured input data) differs from the direct GPS measurement in approx. 20mm in plain parts and 70mm in sloped parts of the swimming pool bottom.