engleski

Computer algorithm for analysis of bedform geometry

Sandy riverbeds are covered by periodic bedforms of different scales, from ripples to antidunes. Under certain flow conditions simultaneously more than one type of bedforms can occur - smaller bedforms are superimposed on bigger ones. The superposition of bedforms causes difficulties for determining individual bedform parameters. In flume experiments bedform data is averaged for entire flow field - sum of total lengths/heights is divided by number of present bedforms. This method has limited applicability to bedform field with uniformly shaped dunes over relatively mild sloped riverbed. If more accurate description of bedform geometry is required other methods for bedform description have to be utilized. This paper presents comparison of two methods for separating different scales of bedforms from Multibeam Echo Sounding (MBES) data: dune geometry components from the mega ripple component. One method determines manual decomposition of the MBES signal, and the other method uses computer algorithm developed for this purpose to calculate signal decomposition. Both methods are described and tested on multiple MBES data sets. As a first application of the separation method individual bedform parameters of bedforms are identified: more particularly wavelength and wave height of bedforms. Results from both methods are then compared in order to validate implemented algorithm logic in computer calculations. The described algorithm represents a more versatile option for accurate description of the shape of the complex bedform geometry, compared to conventional approach. Collected data extracted from bedform profile are visualized using descriptive statistics.

Bedforms ; Multibeam Echo Sounding ; computer algorithm

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