Impact of Influential Parameters on the Formation of Alternate Bars

Abstract

At lower discharge rates, channelized alluvial streams frequently exhibit alternate bars. In this study, bar bed forms were regenerated, and checked the sensitivity of parameters governing the formation process of these peculiar bedforms. Resulted water depth, the number of bars, and bar dimensions were measured by varying flow rate, channel slope, and mean grain size of the bed material. The ratio of Shield number to critical Shield number ranged between 2-11, which agreed with previous research findings. The bar length-to-width ratio of alternate natural bars was compared with modeled outputs, which showed an acceptable resemblance. Results revealed that the highest number of bars could be observed for intermediate discharge values (5 − 8cm3/s) when the bed slopes were maintained between 4.5◦ − 7◦. The formation process of these bedforms was signified once particle Reynold number concentrates towards 20. The bar formation process was curtailed beyond a threshold discharge irrespective of the favorable slope and particle Reynolds number, highlighting the sensitivity of the discharge for this phenomenon. Research outputs can be deployed to predict the possibility of bar formation based on the fluid dynamic and morpho-dynamic characteristics of the desired entity when designing reservoirs, hydropower generating schemes, irrigation water supply systems, etc.