1. How does velocity determine whether a given flow is laminar or turbulent? 2. How does the size of sediment grain affect the speed with which it settles to the bottom of a flow? 3. What kind of bedding characterizes a ripple or a dune? 4. How do braided and meandering stream channels differ? 5. Why is a floodplain so named? 6. What is a natural levee, and how it is formed? 7. What is the discharge of a stream and how does it vary with velocity? 8. How is a streams longitudinal profile defined? 9. What is the most common kind of drainage network developed over horizontally bedded sedimentary rocks? 10. What is a distributary channel?
Depending upon the flow velocity, the roughness of the stream bed, and viscosity, fluids exhibit two types of flow motions - laminar and turbulent. For a flow to be laminar, flow velocity must be very low. If the flow velocity increases considerably, the flow becomes turbulent.
Small-sized sediment grains are carried further away from the source by the river or stream current, whereas the bigger grains settle down to the bottom of the stream bed closer to the source.
Cross-bedded structures are primarily formed by the migration of dunes or ripples in water or air.
Braided stream channels are characterized by the presence of many channels separated by bars or small islands. They form in areas of high relief with limit aerial extent, where an abundant supply of coarse sediment, high water discharge, and little vegetation is present. Braided channels are best developed in distant parts of an alluvial fan system, a glacial outwash plain, or a mountainous reaches of a river system. Meandering channels are characterized by cohesive or well-connected river banks that are harder to erode due to river currents. They differ from braided channels in terms of sediment size (finer-sized), sinuosity (high), and relief (low). Most meandering channels are downward continuations of braided river channels.
A floodplain is composed of fine-grained sediments that settle out of suspension from floodwaters pouring out into a broad-shaped basin with low relief.
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