Natural Features (Geography-Related)

Maybe this post may be a little redundant but wells!

Any idea how the floodplain, levees and Oxbow lake is formed?

Floodplain and Levees
Floodplains are extensive low-lying flat land built up by deposition of alluvial soil due to repeated flooding. Levees are wide, elevated bank built up deposition of alluvial soildue to repeated flooding. During a flood, the rain that falls will result in water to overflow from the bank and thus causes the coarser and heavier materials to be deposited at the river bank and the lighter and finer materials to be carried further away and get deposited on the plain. As repeated flooding takes place, this alluvial soil will then be deposited layer upon layer, forming a thick, rich alluvial soil deposits known as floodplain. With coarser materials deposited at the bank, a layer above the floodplain is formed to form a natural embankment known as levees.

Oxbow-Lake
Firstly, understand how a meander is formed. In teh lower course, the velocity is low and so the river will flow through bends. These bends have an outer bank where erosion by undercutting takes place and an innderbank where deposition takes place. Over time, the outer bankwill form a concave shape and the inner bank will form a convex shape and thus forming a meander that is defined as the twist and turn of the river to form hoop-like bends.

So, now we will see how an oxbow lake is formed. Oxbow-lake is defined as a cresent-shaped lake found in floodplains and near a meander.Understand that oxbow lake is usually formed in the lower course of the river due to its low velocity where sediments are allowed to set down in river bed. In the outer concave bank, erosion by undercutting takes place that causes the meander's neck to be separated only by a narrow neck. And due to deposition in the inner convex bank, the oxbow lake will cut off from the river channel and flow in a straight stream.

Just for fun! (:
There are 4 ways to manage the river! River channelisation refers to the different strategies and methods to control both the volume and speed of flow of river.
1) River re-alignment that involves the altering of river channel by removing huge boulders or by widening and deepening the river channel by dredging. This helps to increase speed of flow.

2) River-resectioning that involves shortening of river to increase speed of flow.

3) Vegetation Planting and Clearance that involves binding the soil together and to increase speed of flow.

4) Bank protection that involves building artificial embankments, dykes and levees to preent the collapse of the river bank during heavy downpour when there is a increased in river volume. This is a really cool method as it actually have the ability to reduce the amount of erosion due to the force of running water that will thus reduce the amount of sediments to be deposited and piled up and thus increasing capacity of river to reduce threat of flooding.

That's all for today(:

Joelle