October- December

Hi again students!

I will begin to upload your topics for the 2nd bimonthly evaluation.

COASTAL ENVIRONMENTS

The coast as a system

The coast is also an open system. It has inputs, flows, stores, and outputs.  The coast is the transition zone between the land and the sea.

Coasts have two main zones: the ONSHORE (inland), and the OFFSHORE (sea).

To understand the coast as a system, we have to consider 4 basic elements:

·         LAND. Physical processes, geology and river sediments, and ecosystems

·         SEA. Physical processes, sea level, water depth, ecosystems

·         WEATHER. Wind strength and direction, rainfall, temperature, storms

·         HUMAN ACTIVITY. Settlements, development, coastal management.

 

Marine processes.

Water can change the aspect of the land. Waves can erode, transport and deposit materials. Waves are created by the wind. Wind moves the surface of the water.

As waves get near the coast, they enter into shallow water. When this happens, we can observe two phases:

·         SWASH. It’s the forward movement of water  through  the beach.

·         BACKWASH. It is the water running back down the beach.

 

Because of this movement, we may recognize CONSTRUCTIVE and DESTRUCTIVE waves.  Constructive waves deposit material on the beach (deposition). Destructive waves drag down material from the beach.

 

 

 

 

 

Coastal landforms

The coast may change its form mainly because of:

·         Hydraulic action: this results from the force of the waves hitting the cliffs

·         Abrasion: cause by waves picking up stones and hurling the at cliffs

·         Corrosion: the dissolving of rocks by sea water

·         Weathering: breakdown of rocks caused by freeze thaw, salt crystals,  vegetation

·         Erosion: caused by wind and rain

·         Mass movement: caused by gravity (rocks falling down)

 

The most common coastal landforms shaped in the coasts are the HEADLANDS and the BAYS. As a result of these, we may also find cliffs,  caves, arches, stacks, and stumps

 

 

 

 

Spit

 

 

Tombolo

 

Cuspate foreland

 

Lagoon

 

 

Sand dune

COASTAL ECOSYSTEMS UNDER THREAT

 

Coastal ecosystems offer some value to people, but, some of human actions threatens their existence.

Coral reefs

Coral reefs are important to people because of:

·         Their biodiversity: lots of coral and fish species

·         Protection from tropical storms

·         Rich fish stocks (food supply for LICs)

·         Tourism

 

Since coral reefs presents these benefits, they attract a lot of persons. This may have negative results to the reef, such as:

·         Increased pollution

·         Removal of fish

·         Sewage and fertilizers to the sea

 

Mangroves

Mangroves, as the other ecosystems, provide some benefits to people:

·         Nurseries of fish and crustaceans

·         Mangrove roots trap sediments and help creating new land

·         Protection from storm surges

Threatens to mangroves:

·         Aquaculture

·         Deforestation

·         Land reclamation to build hotels

·         Expanding agriculture

 

 

Salt marshes

Specific threatens to salt marshes include:

·         Reclamation of land to create farmlands (agriculture), industrial and port development

·         Industrial pollution (power stations and oil refineries).

·         Agricultural  pollution: fertilizers and pesticides

·         Development of marinas and recreatiñonal facilities

 

Coastal sand dunes

·         People uses these areas as recreational spaces (biking and horse riding)

·         Loss of vegetation

·         Risk being built over

·         Tourism (golf courses and caravan sites)

 

 

COASTAL CONFLICTS

The coast is also a SYSTEM. We have things entering the system (INPUTS), and may stay in there (STORES), or also, they may pass through it (TRANSFERS) to then leave (OUTPUTS).

If there is a balance between inputs and outputs, is said to be in EQUILIBRIUM. Equilibrium can be easily broken by human activities; Human can use ecosystems lands and their resources to develop industry and for recreational activities.  As a result of this, we can find conflicts between CONSERVATION and DEVELOPMENT

CONFLICTS BETWEEN COASTAL USERS

Since coasts offer a lot of goods, we can find  types of users competing for them:

·         Local residents

·         Employers (shops, offices, factories

·         Farmers

·         Fishermen

·         Port authorities

·         Transport companies

·         Tourists

Because of the people taking advantage of these ecosystems, the natural environment is being damaged. Coastal ecosystems are being affected by 3 activities: the ships serving the oil and gas terminals; discharges from industrial plants; agricultural chemicals into the sea. One effective solution would be to separate or assign areas to the different activities.

 

 

 HAZARDOUS ENVIRONMENTS

A hazard is an event that threatens or causes damage or destruction to people and/or their property.  A natural hazard is one produced by environmental processes and involves events such as storms, floods, earthquakes and volcanic eruptions.

GEOLOGICAL	CLIMATIC	BIOLOGICAL	TECNOLOGICAL
Earthquakes	Storms	Fires	Nuclear explosions
Volcanic eruptions	Floods	Pests	Accidents
Landslides	Drought	Diseases	pollution

 

An important aspect of all hazards is related to risk. Risk is the probability of an event to happen and the scale of its possible damage. Also, there are 4 main aspects to know about a hazard:

·         Distribution: Where do they occur?

·         Frequency: Do they occur regularly?

·         Scale: How much damage?

·         Prediction: Can the hazard be predicted?

To minimize the damage made by a hazard, we must take precautionary actions. These actions are known as ADJUSTMENT or MITIGATION

 

 

EARTHQUAKES

An EARTHQUAKE is a sudden and brief period of intense ground-shaking. They are caused by the different movements of tectonic plates.

There are two scales to measure the intensity of earthquakes. The RICHTER SCALE measures the movement  strength according to the amount of energy released. This strength is measured with a seismograph, and the scale runs from 2.4 to over 8.0.  The MELCALLI SCALE is based on the amount of damage done and it runs from 2 to 12.

We can identify different elements of earthquakes. The first one is the focus. The FOCUS is the centre of the earthquake underground. The EPICENTRE is the point on the surface directly above to the focus.

The main threat of earthquakes is their ability to shake building so they may fall apart and collapse. Nowadays, buildings are designed so they can resist earthquakes. Another effect of earthquakes is the tidal wave or TSUNAMI. Tsunamis are caused by earthquakes happening under the sea, so they generate large and destructive tidal waves.

VOLCANIC ERUPTIONS

What is a volcano? A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. When pressure builds up, eruptions occur. Gases and rock shoot up through the opening and spill over or fill the air with lava fragments. Lava, ash, and gas emissions threaten not only people but their environment.

Volcanoes can have a very serious effect on the lands and people around them when they erupt.

·         Buildings are destroyed and people are made homeless.

·         People are killed.

·         Clouds of ash cover plants making them inedible.

·         Poisonous gases kill people and animals.

·         Dust causes pneumonia and illnesses to the survivors.

·         Dark skies, severe winds and heavy rains may follow an eruption for months afterwards.

                           

 

 

Reasons for living in high risk areas

People build cities and live in them knowing that many of these are high risk areas. Some of these cities are constantly hit by hurricanes and earthquakes. Why?

·         A lack of education may mean that residents DO NOT KNOW about the risks of living in these cities.

·         Because of the benefits of living in these places

·         People are unable to move from hazardous areas due to the lack of money or permanent jobs. Also, some of these persons and/or families have been for generations and they feel comfortable living there despite the hazards.

·         The investment made in these cities. People have invested in houses, buildings, attractions, etc., and since living there will represent a certain amount of risk, houses and living will be cheaper.

Living near a volcano may offer some other benefits, such as minerals (diamonds, gold, and copper), fertile soils, tourism, etc.