Method for determining the bed load discharge by the parameter of the average depth of the layer of moving materia

Abstract

The object of the study in this paper is the dunes form of transport of bed load in the channels of lowland navigable rivers. An accurate assessment of the bed load discharge is important when considering river morphology, conducting dredging and river regulation works to ensure navigational conditions, as well as when designing various engineering structures. This paper analyzes modern methods for measuring bed load discharge based on dune parameters. Considering the identified shortcomings and limitations of existing measurement methods, a new method for measuring bed load discharge is proposed. A distinguishing feature of the proposed method is the use of the average depth of the layer of moving material when determining bed load discharge. This parameter is defined as the ratio of the area of the moving material to the length of the moving material layer. Essentially, the moving material consists of dunes identified after filtering out minor bottom protrusions. The advantage of this method lies in using of the average depth of the moving material layer, which allows for all the dunes identified in the longitudinal profile to be accounted for when calculating the bed load discharge. The use of areal dune characteristics also enables the determination of bed load discharge in rivers where the bottom relief consists of deficit dunes.To confirm the effectiveness of this method, a series of experiments were conducted in the Channel Laboratory of the State Hydrological Institute in hydraulic flumes with a movable sand bed. The channel bedforms consisted of three-dimensional dunes. The flow regime in the flume was adjusted to replicate conditions typical of lowland navigable rivers. The experiments confirmed that even with the complex three-dimensional structure of the channel bedforms, the proposed method is highly accurate compared to existing methods.