How is a delta bar formed?

A delta bar is formed specifically at the confluence of streams, where the flow of water from two rivers or streams meets and interacts. This area is characterized by the deposition of sediment brought by the water, which creates a bar-like formation. When the waters flow together, the decrease in velocity at the confluence allows for these sediments to settle and accumulate, thus forming a delta bar.

This process highlights the interplay between sediment transport and water flow dynamics, which is crucial to understanding riverine systems. The deposition is often influenced by variations in water volume and speed, which tend to fluctuate with changes in the sources of the water bodies involved. In contrast, other options pertain to different geological processes: sediment accumulation on floodplains, water flow changes due to droughts, or erosion along riverbanks, none of which directly results in the specific formation of a delta bar through the interaction of two streaming waters.