Summary
Explains how natural levees form during river floods due to changes in water velocity and sediment deposition patterns.
Formation of Natural Levees
Highlights
Natural Levee Formation Process
Natural levees are created when a river floods its banks and spreads onto the floodplain. The increased surface area and friction encountered by the overflowing water reduce its velocity and energy, thereby diminishing its capacity to transport bedload. This leads to a decline in the river's competence to carry sediment further from the banks.
Sediment Deposition and Levee Structure
As the river's energy decreases, it first deposits larger sediment closer to the banks, while finer sediments are carried further across the floodplain. This process results in a sediment profile where particle size decreases with distance from the river bank to the bluff. The accumulation of larger bedload near the bank causes the bank to rise, creating gently sloping levees towards the floodplain.