Multiscale characterization of migrating sand wave in mining induced alluvial channel

Sediment transport mechanism is highly influenced by the hydraulic condition of a river. Sand mining from river bed changes the geometry of the bed and influences the flow parameters, and thus can alter the hydraulic condition of a river. Our study is based on laboratory experiments for sand bed channel with a rectangular mining pit. We present both physical and dynamic characteristics of a mining induced channel from the bed elevation data obtained from Seatek instrument. Physical characteristics shows erosion in the entire channel as the flow in the channel is kept higher the flow required for sediment movement. Two distinct water surface slopes occur in the test section centering the mining pit. Shear stress along the test section is determined and observed higher value of downstream shear stress than upstream of the pit. Erosion at the downstream of the pit is more than the upstream and migration of upstream edge occurs. Dynamic analysis of sand wave depending on statistical approach is carried out to investigate the movement of sediment under the influence of mining. Celerity of sand wave increases with increase in flow velocity during the initial time span (1-4 h) but in a later time interval (4-7 h) it decreases with increase in flow velocity. It has been found that celerity of sediment initially increases with scale size and then decreases, which indicates a higher resistance is being offered by sediment at high scale.