Delta

Where can you find delta? Mouth of river

What is a delta? A flat depositional plain formed at the river mouth

Types of delta

Arcuate delta Triangular in shape E.g. river Nile, Egypt, Africa.

Map of Nile

The Nile Delta Satellite Image

Bird’s foot delta Look like a bird’s foot E.g. river Mississippi, U.S.A, North America.

Mississippi Delta Satellite image

Estuarine delta No particular shape E.g. river Amazon, Brazil, South America. Estaurine delta

The Amazon River

Satellite image of Amazon river mouth

A B Examples from China C

Huang He Satellite image Arcuate delta

B Chang Jiang delta p. 48 Shanghai Satellite image Estaurine delta

C. Zhu Jiang Delta Estaurine delta Satellite image

Discussion What are the uses of delta to man? Explain your answer. Quote examples. What are the favourable conditions for the formation of delta? (Think in terms of the river characteristics and the coastal environment……)

The uses of delta …..

And many more ….

Conditions favouring the formation of delta Characteristics of the river River carries a large load There are few or no lakes along the river

Characteristics of the coastal environment Sheltered bay Weak tides and waves Removal of sediment is slower than deposition Gentle offshore slope Shallow sea Presence of vegetation

Formation of delta When a river bring down a large amount of sediment River reaches the sea, it slows down Particles group into larger and heavier particles (flocculation process) When sediment is deposited faster than it can be removed, delta is formed

Exercises Complete the worksheet Homework – Nam Chung River, p.55-56