Semiautomatic Algorithm for the Interpretation of the Bedforms and Statistical Analysis

Abstract

This study presents a methodology to simplify the identification of the primary bedforms (mediumlarge dunes) present on a compound riverbed. The paper refers to a field study conducted on a straight free flow reach of an alluvial river (i.e. River Po in Italy) in January 2021. The surveys were carried out employing a multibeam echosounder which allows a large data collection, which was processed realizing river bed DTMs. The identification of the dunes along transects occurs through the implementation of a semiautomatic algorithm able to analyse the bed elevation profiles and to recognize the troughs and the crests of the primary dunes based on the threshold values of length obtained through to a spectral analysis. Once the dunes are recognized, characteristic parameters of the dunes (wavelength, wave height and steepness) are estimated, by which a statistical analysis is carried out to figure out the most frequently recurring dunes on the riverbed. The semiautomatic algorithm proves to be able to handle a large amount of data, providing a reliable interpretation of the riverbed and it is also consistent with results from previous studies. Starting from the present analysis, it is possible to develop the study of the bedforms kinematic that represents a key issue to quantify the volumes of solid bedload transport, in order to cross the typical limitations derived by the traditional bed load sampling methodologies.