Select Page

Deltas

Deltas are landforms formed at the mouth of a river, where the river meets a body of water with a lower velocity than the river (e.g. a lake or sea),  resulting in the reduction in the river’s capacity to transport sediment.

Deltas are dynamic areas that change quickly due to the erosion of unstable land during storm and flood events and the creation of new land. Deltas are fertile areas which often support large populations due to their agricultural productivity. Examples include the Ganges delta in Bangladesh and the Nile delta in Egypt.


The Nile Delta

Deltas are formed in the following way:

1.     Rivers typically contain their highest sediment loads near their mouth, where they meet seas and oceans. As the river enters a body of water its velocity

2.     At the mouth of the river, the flow of water becomes increasingly lateral. This lateral movement of water reduces hydraulic radius and increases wetted perimeter;

3.     This causes sediment to be deposited, as does flocculation where clay sediments join together, gain in mass and sink.

4.     Over time sediment builds up. This can create small islands that split the channel in the same was as braided streams; 

5.     This continues until the river splits as more islands form;

6.     If sediment is fine-grained bird’s foot deltas can be created. If sediment is coarse-grained arcuate deltas form. 

Support

While you are here, please consider supporting A Level Geography. 

If you have found this site useful please support us keeping A Level Geography free by making a small, secure donation via Paypal towards to the running costs of the site.

Many thanks,
Anthony

Drainage basin hydrological cycle

Find out about the characteristics of the drainage basing hydrological cycle.

Storm Hydrograph

Hydrographs can be used to illustrate discharge. These can be used to show annual discharge patters of flow in relation to climate.

The long profile of a river

The long profile of a river shows changes in the height (altitude) of the course of a river from its source to its mouth.

Water Balance

The balance between inputs and outputs is known as the water balance or budget.  The water…

Erosion, transportation and deposition

There are three main types of processes that occur in a river. These are erosion, transportation and deposition.

Changing channel characteristics

The characteristics of a river channel change along its long profile. Changes occur in the cross profile, wetted…

Pin It on Pinterest

Share This