BEDLOAD MEASSURMENTS USING ADCP - CONFIRMATION AND ANALYSIS

Measuring the bedload transport in fluvial environments is a difficult and labor-intensive task. The temporal and spatial variability of the bed load together with the instrument disturbance can induce stochastic and systematic uncertainties. These data are usually considered as unreliable, which complicates the further elaboration of the sediment transport behavior. Statistically valid measurements are extremely important for the evaluation of the sediment transport masses, especially in large navigable or heavily exploited rivers. Recently, many studies showed that the measurements with the bottom tracking (BT) feature of the acoustic Doppler current profilers (ADCP) have emerged as a promising technique in evaluating the bed load (Rennie, et al., 2002; Gaeuman & Jacobson, 2006; Latosinski, et al., 2017). The use of these non-intrusive techniques could significantly reduce the uncertainty. Firstly, they do not disturb the riverbed and are easy to deploy. Secondly, very long and frequent measurements can be easily performed. Widespread implementation of the ADCP BT bedload technique would reduce the scarcity and statistical uncertainty of bed load data. The ADCP velocity is commonly denoted as the apparent velocity. It represents a velocity calculated as the difference between the Bottom Tracking (BT) mode and the GPS velocity. Nevertheless, the bedload transport is usually characterized with near-bed turbulent conditions and the rough loose bed. Therefore, the acoustic footprint contains data from mobile and immobile particles, as well as the undulations of the bottom. The signal is noisy and contains erroneous data. This study aims to develop a methodology of using the ADCP BT Mode to measure the velocity of the bedload. The capability of two commercially available ADCPs were tested in controlled laboratory conditions (Conevski, et al., 2018). In addition, the results from two measurement campaigns are presented. The first measurement is in the Devoll River Valley, Albania, while the second campaign is in Oder River in Germany. This work offer a correlation and confirmation of a potential usage of the filtered temporally averaged ADCPs velocity and eventual application of the kinematic transport model (e.g. Kinematic Transport Theorem) in future