Crowded Coasts

Crowded Coasts – An introduction

Understand that geology affects a coast’s topography and relief

Draw spider diagrams to show how coasts vary physically, and the variety of human uses of coasts

Understand that coastal populations are increasing worldwide

Starter

Key Questions to consider:

Why do coasts vary so much?

What are they used for?

Why?

Mangrove Coastline

Low trees and shrubs with dense roots that grow in the marginal tidal zones between TROPICAL seas and land.

Adapted to area due to thick waxy leaves which conserve water by reducing transpiration during low tide.

Roots anchor into mudflats

Salt tolerant ‘halophytes’

Protects against storm surges and tsunamis

Tropical Coastline

Salt Marsh coasts

Salt Marsh

Defined as the vegetation that occurs on muddy shores between mean high water neap and extreme high water spring tides, form on the shore due to a lack of wave action and the tide.

Incoming tide moves across the sheltered shore bringing sediment and detritus, the lack of wave action results in this material settling out at slack water

Accretion takes place; sediment builds up forming soil and can even raise the level of mud.

Abiotic Factors : (Non Living)

Saline Mud/Soil : Seawater deposits salts (solutes) in the sediment. Causing problems for plants growing

Waterlogged Soil: The air spaces within the soil are filled with water rather than air. Roots need oxygen for respiration as much as other parts of the plant. Long-term waterlogging creates an anaerobic condition of black mud. Which is toxic to plants.

Drag and Scour: The tidal movement across the surface causes a sideways drag on the plant. With two tides a day this will possibly uproot the plants. The water contains sediment like sand and mud particles and this will scour the plants like being buffed with sandpaper.

Mudflats

Polar Coastline

Sand Dunes

Reef Coastline

Great Barrier Reef in Australia is 1500km long and comprises of 2900 different reefs

3 types of reef: Fringe, barrier reefs and atolls. Charles Darwin first found these three

Helps dissipate wave energy

Fragile and open to exploitation

Desert Coastline

The British Seaside?

What is a coast?

‘ that part of the land most affected by its proximity to the sea and that part of the ocean most affected by its proximity to the land ’

It’s called the ‘ Zone of Transition ’

The Coast is the narrow zone where the land overlaps the sea and interacts

It is affected by Terrestrial, Human, marine and Atmospheric processes and their relationships.

It is the most varied and rapidly changing of all landforms and ecosystems.

The Coastal Zone

The Importance of Coastal Environments

The Coastal zone is an interface between the sea and the land. Where the marine and terrestrial processes combine to produce a variety of changing landforms.

Coasts suffer from rapid erosion and flooding thus can threaten lives and property.

Changes to coastlines are both short term (eg Storms) and long term (Rising sea levels)

Factors influencing coasts The Nature of Coasts

Sea

Coastal (marine) ecosystems

Wave energy and direction

size and type of waves

Local currents and LSD

Tidal changes

Water depth

Offshore sediments

Long-term changes in sea level

Land

Shape of the coastline

Relief

Presence or lack of beach

Structure of the coast

Resistance of the rocks

Sub-aerial processes

River sediments

Coastal (land) ecosystems)

Weather and Climate

Wind strength and direction

Rainfall and temp

Storms and surges

Human activities

Intervention in natural ecosystems

Use of land for development

Exploitation of resources

Did you know?

3 billion people live within 100km of the coast

Two thirds of our largest cities are within 60km of the sea

Coastal population densities are usually 80 people/km2 – 50% more than inland areas

These can rise up to 1000+ in the Nile and Ganges Deltas

Coastal ecosystems are coming under constant pressure from human activities

There is constant competition for it’s natural resources.

Coastal management is becoming a major issue

Human intervention has lead to unexpected impacts

With human development and global warming demands will increase so need for management, particularly sustainable management strategies are needed.

THE FACTORS

Waves

Created by the transfer of energy from the wind blowing over the surface of the sea.

Tsunamis

Are created not by the wind but by submarine shock waves generated by earthquakes or volcanic activity.

With waves the greater the wind the greater the frictional drag and therefore the size of wave

Those that travel short distances and are the result of local waves are seen as sea waves

Those that are formed from distant storms and travel large distances are known as swell .

Wave Energy

Wind velocity

Period of time the wind has blown

Length of the fetch

Exercise 1.

On a map of the UK find areas which have the biggest fetch

Wave terminology

CREST

TROUGH

WAVE PERIOD

LENGTH

VELOCITY

STEEPNESS

ENERGY

SWELL

CREST – Highest point of the wave

TROUGH

WAVE PERIOD

LENGTH

VELOCITY

STEEPNESS

ENERGY

SWELL

TROUGH – lowest point of the wave

WAVE PERIOD

LENGTH

VELOCITY

STEEPNESS

ENERGY

SWELL

WAVE PERIOD – Time taken for wave to travel one wave length

LENGTH -

VELOCITY

STEEPNESS

ENERGY

SWELL

WAVE PERIOD – (T) Time taken for wave to travel one wave length

LENGTH – (L) Distance between two successive waves

VELOCITY -

STEEPNESS

ENERGY

SWELL

VELOCITY – (C) speed of movement of a crest in a given period of time

STEEPNESS -

ENERGY

SWELL

STEEPNESS – (H/L) ratio of wave height divided by length it can not exceed 1:7 (0.14) as it will break

ENERGY

SWELL

ENERGY – (E) expressed as E~ (Is proportional to) LH2

SWELL –

ENERGY – (E) expressed as E~ (Is proportional to) LH2

SWELL – have low height, gentle steepness and long wave length

World map – coastal hotspots?

Types of coasts?

Trade Coasts?

Recreation coasts?

Residential coasts?

Resource coasts?

Exercise 2: Complete a table with examples of each

High Value coastal environments?

Exercise 3: Identify the features, opportunities, value and pressures for each of the following:

Mangroves Reefs Salt Marshes

Exercise 4

Annotate photo to identify

Physical features

Human features

Opportunities

Threats/pressure

So...

As you can see there are many different forms of coasts and they vary enormously.

In groups define the benefits for differing regions in terms of geology and relief that an area may possess and see if you can think of examples from your own ideas.

Finally