BIG PICTURE: WHAT LANDFORMS ARE FOUND IN THE

LOWER COURSE OF A RIVER?

Lesson Outcomes

What: Understand and describe the key features of a flood plain

How: By explaining and describing how a river delta it is formed.

Why: Simulate a model to identify the 3 types of river delta

CONNECT: WHAT IS A FLOOD PLAIN?

The following images are of various flood plains in

the UK write a 2 sentence definition to describe what

you think one could be.

RIVER SEVERN FLOOD PLAIN

Worcester Floods, 2007.

RIVER THAMES FLOOD PLAIN

RIVER TRENT FLOOD PLAIN

CONNECT: SO…WHAT IS A FLOOD PLAIN?

• A floodplain is the name given to flat land bordering a river.

• Floodplains found in the lower course of a river.

• They are made up of alluvium.

• Alluvium refers to the sediment (sand, silt, and clay) deposited during floods.

• When a river overflows, the floodplain is covered with water.

Correct your definition to make sure it is accurate.

How close were you? Give yourself a mark out of 5 to show how accurate your initial

definition was!

ACTIVATE: HOW DO FLOODPLAINS FORM?

Floodplains and levees are formed by deposition in times of river

flood. The river’s load is composed of different sized particles.

When a river floods it deposits the heaviest of these particles first.

The larger particles, often pebble-sized, form the leveés. The sands,

silts and clays are similarly sorted with the sands being deposited

next, then the silts and finally the lightest clays. This deposition

makes up the floodplain.

Floodplain formation

The River

Nile

The

Mediterranean

Sea

The Nile

Delta

ACTIVATE: WHAT IS A RIVER DELTA?

THE NILE DELTA

ACTIVATE: WHAT IS A RIVER DELTA AND HOW

DO THEY FORM?

What is a River Delta?

• A river deltas are found at the mouth of a river, where the river meets the sea.

• At this point the river is carrying too heavy a sediment load for its velocity ( this means the speed the river is flowing) therefore deposition occurs.

• The deposited sediment load over time forms river deltas.

TASK:

Using the information you have already learnt today about lower

course features fill in the missing words on your worksheet to

explain key processes (task 1 & 2)

The

‘Grand

Rhone’

Grand

Rhone

Petit Rhone

Mediterranean Sea

The mouth of the Rhône

ACTIVATE: HOW DO DELTAS FORM?

silt clay sand

TASK:

Using the information you have now learnt today about deltas fill in

the missing words on your worksheet to explain key processes

(task 3 & 4)

ACTIVATE: HOW DO DELTAS FORM?

silt

clay

sand

Delta Formation:

The top of the delta is a fairly flat surface. This is where the coarsest

river load is dropped. The finer particles are carried into deeper

water. The silt is dropped to form a steep slope on the edge of the

delta while the clay stays in suspension until it reaches the deeper

water.

ACTIVATE: HOW DO DELTAS FORM?

TYPES OF RIVER DELTA

There are 3 types of river delta;

1. Arcuate or Fan shaped: The land around the river mouth arches

out into the sea, the river splits many times on the way to the sea,

creating a fan effect.

2. Cuspate: The land around the mouth of the river juts out arrow-

like into the sea.

3. Birds foot: The river splits on the way to the sea, each part of

the river juts out into the sea, like a bird's foot.

REFLECT: HOW DO RIVER DELTAS DIFFER?

There are 3 types of river delta;

Draw an appropriate diagram to illustrate each.

Use the play dough to help you visually model what

each look like!

1. ARCUATE OR FAN-SHAPED

The Niger Delta in

Nigeria.

2. CUSPATE

The Ebro

Delta in Spain

3. BIRD’S FOOT

The

Mississippi

Delta in the

USA

NAME THE FEATURE…

HOMEWORK: HOW DOES A RIVERS JOURNEY

CHANGE FROM SOURCE TO MOUTH?

Today’s homework is a reflection on what you have

learnt so far about the characteristics of a river.

Complete the worksheet to demonstrate your learning.

Don’t forget to reflect on your learning in the support

clinic box!