Sediment in Streams

The alluvium is the sand and silt deposits around the floodplain areas. Because this sediment is very full of minerals, these deposits lead to fertile agricultural territory.

In general, there are three major zones of a stream's system. The first zone in the headwaters area of a stream is the zone of sediment production. The second is the zone of transport throughout the length of the stream's course. Finally, you have the zone of deposition, where the mouth of a stream opens out into quieter water.

SEDIMENT IN STREAMS

The sediment in a stream is called its load. It is divided into the dissolved, suspended, and bedload areas. The bedload is heavy and made of pebbles or boulders. Traction and saltation efforts bring them downstream. Suspended particles are visible but are light enough to be suspended in water. Then you have your dissolved load, usually mineral ions like potassium, sodium, chloride, calcium, and bicarbonate. They are unaffected by the flow of water.

Streams move the fastest at the Bankfull stage, which is just prior to flooding. When streams overflow, the floodplain around it will have sediment that gets deposited along the banks when the flow rate drops dramatically after flooding. A natural levee is created along the edges in a ridge when flooding is repeated.

Streams all have longitudinal profiles. They have all three zones in them, from the headwaters to the mouth. You will see this profile mapped out in terms of its elevation along its course and the gradients at each level. The profile is then a map of elevation versus length. You can see the energy in the stream drop from top to bottom but not in a linear pattern. The equilibrium of a stream is its grade, where the stream tries to balance the effects of erosion, discharge, gradient, velocity, and other things.

The base level of a stream is whatever elevation it can erode to at its lowest point of its mouth. The base level is usually the ocean at sea level but a lake can be the base level of a stream entering it. If the sea level changes for any reason, the base level for many streams will also change. If you add a dam to the stream, you will get a rise in its base level. If you drop the base level, the stream will get deeper. This is because all streams