Coastal Management (Cambridge (CIE) O Level Geography)

Managing the Impacts of Coastal Erosion

• There are conflicting views about using a particular type of engineering for coastal defence

• Most coastal managers aim to use a range of methods depending on the value of what is being protected

• This method is known as Integrated Coastal Zone Management (ICZM)

• ICMZ aims to use a combination of methods to best reflect all stakeholder's needs

Soft engineering methods

• Soft engineering works with natural processes rather than against them

• Usually cheaper and do not damage the appearance of the coast

• Considered to be a more sustainable approach to coastal protection

• However, they are not as effective as hard engineering methods

Soft Engineered Defences

Hard engineering methods

• Hard engineering involves building some form of sea defence, usually from concrete, wood or rock

• Structures are expensive to build and need to be maintained

• Defences work against the power of the waves 

• Each type of defence has its strengths and weaknesses

• Protecting one area can impact regions further along the coast, which results in faster erosion and flooding

• Hard engineering is used when settlements and expensive installations (power stations etc) are at risk - the economic benefit is greater than the costs to build

Hard Engineered Defences

Prediction

• Early warning systems allow communities to prepare (evacuate or take shelter) before flooding occurs

• Two methods are used to help forecast coastal flooding:

  • Past records (diaries, newspapers, government/council records etc)

    • These will identify areas that are at high risk of flooding and their frequency

  • Modern technology - GIS, satellite and computer monitoring, weather stations (local and national) etc

    • These allow for forecasting and tracking potential hazard events i.e.

      • Tropical storms - track the storm's path and associated storm surge

      • Earthquakes - size and position if underwater and possible tsunami outcome

• Both these methods of forecasting help officials to say when and where the event will occur

• It indicates the possible strength and scale of the flooding, and the likelihood of damage and death

Prevention

• Prevention is about taking action that reduces or removes the risk of coastal flooding

• Actions include:

  • Flood defences

    • These are built along high-risk stretches of coast 

  • Emergency centres

    • Centrally placed on higher ground where people can be safe from flooding

  • Early warning systems

    • Allows for preparation or evacuation of an area

  • Education

    • Informing local people on what to do if and when a flood occurs

  • Planning

    • Planning any new development away from high-risk-areas

    • Designing buildings to cope with low levels of flooding

      • Elevating buildings so that flood waters can pass underneath

      • Flood proof buildings with raised foundations (fixed or mechanical)

      • Reinforced barriers

      • Dry flood proofing - sealing a property so that floodwater cannot enter

      • Wet flood proofing - allows some flooding of the building

  • Buffer zones

    • Areas of land are allowed to flood before reaching settlements

      • This allows the energy in the surge to dissipate slowing down the distance the floodwater will travel

      • It can mean moving people away from the coast which could be controversial 

Coastal strategies

• Management of coastal regions is performed by identifying coastal cells

• This breaks a long coastline into manageable sections and helps identify two related risks:

  • The risk of erosion and land retreat 

  • The risk of flooding

• Identification allows resources to be allocated effectively to reduce the impacts of these risks

• The 'cost to benefit' is easier to calculate using coastal cells

Shoreline management plans

• Shoreline Management Plans (SMP) set out an approach to managing a coastline from flooding and erosional risk

• The plans aim to reduce the risk to people, settlements, agricultural land and natural environments (salt marshes etc.)

• There are four approaches available for coastal management, with differing costs and consequences:

• Hold the line

  • Long term approach and the most costly

  • Build and maintain coastal defences so the current position of the shoreline remains the same

  • Hard engineering is the most dominant method used with soft engineering used to support

• Advance the line

  • Build new defences to extend the existing shoreline

  • Involves land reclamation

  • Hard and soft engineering is used

• Managed realignment

  • Coastline is allowed to move naturally

  • Processes are monitored and directed when and where necessary

  • Most natural approach to coastal defence

  • Mostly soft engineering with some hard engineering to support

• Do nothing

  • Cheapest method, but most controversial of the options

  • The coast is allowed to erode and retreat landward

  • No investment is made in protecting the coastline or defending against flooding, regardless of any previous intervention

• Decisions about which approach to apply are complex and depend on:

  • Economic value of the resources that would be protected, e.g. land, homes etc

  • Engineering solutions - it might not be possible to 'hold the line' for moving landforms such as spits, or unstable cliffs 

  • Cultural and ecological value of land - historic sites and areas of unusual diversity

  • Community pressure - local campaigns to protect the region

  • Social value of communities - long-standing, historic communities

Case Study - Super Typhoon Haiyan

Background

• Typhoon Haiyan (locally called Yolanda) was one of the strongest ever-recorded tropical storm to hit the Philippines 

• It made landfall on the 8th of November 2013 as a Category 5, with sustained winds of over 195 mph (315 km/hr)

• The Philippines are a series of islands located in the South China Sea, east of Vietnam and north of Indonesia

• The islands regularly suffer from typhoons that sweep in from the southwest every year during the tropical storm season

• The islands sit in an area of usually warm ocean water, however, at time of storm, the sea temperature was 30°C

• Sea level rise (since 1900, has increased 20cm around the world) is a factor as higher seas are known to contribute to greater storm surges

• Abstracting too much groundwater has caused parts of the country to sink

• Tacloban stands at the end of a bay that is funnel shaped and this squeezes water into destructive storm surges

Formation of tropical storms

• All tropical storms need warm, deep water (>27°C and >70 m depth) and sufficient spin from the earth’s rotation (Coriolis force), hence why they form between 5-20° N and S of the equator

• Warm water encourages evaporation from the sea surface, and as the air rises, it cools, condenses, releases latent heat and forms large thunderclouds

• Heat from below causes further vertical growth and this creates an intense low pressure

• Tropical storms begin with a merging of several storms on the eastern side of an ocean

• A major low-pressure cell develops and as winds are drawn in, the whole system begins to spin anticlockwise and westwards

• Winds rotate around a central eye, where cold air descends creating an area of calm

• The strongest winds are within the wall of the eye.

Typhoon Haiyan's timeline

Path of Typhoon Haiyan November 2013

Typhoon Haiyan's characteristics

Preparation for Typhoon Haiyan

• The Philippines, despite being an LEDC, take disaster preparations seriously as they have experience of typhoon impacts, as they are usually the first Pacific landmass in a typhoon's track

• The Philippines have been practicing risk reduction and resilience for decades and have published risk maps and provided evacuation shelters

• When Haiyan made first landfall, the International Charter on Space and Major Disasters was activated, this allowed relief agencies, in times of disasters, to have access to satellite data from space agencies to help in relief and recovery

• The military deployed planes and helicopters in advance to areas expected to be worst hit

• Community buildings, such as convention centres, were designated as storm shelters, but there were concerns that they would not withstand the wind

• As a result of years of community preparedness and education, there were evacuations of whole islands, such as Tulang Diyot, with all 1000 residents leaving ahead of Haiyan

• The local mayor won an award in 2011 for community work based on the “Purok system”, which is where community members agree to deposit their own money into a community fund, on a regular basis, for post-disaster assistance, rather than waiting for government aid

Impacts of Haiyan

Immediate relief

• The immediate response was from the survivors, who searched flattened buildings for bodies

• The government was criticised for being slow in its response, and people began looting to find food supplies

• Roads were undamaged, but debris slowed rescue vehicles

• Airports and harbours were closed meaning emergency teams had to travel slowly on foot, which hampered aid distribution

• International charities sent emergency supplies, centred on Tacloban airport with the UK and USA sending diggers, land rovers and heavy lifting gear

• The European Commission released $4m in emergency funds and the UK Rapid Response Facility provided $8m in aid

• Twelve IFRC (International Federation of the Red Cross) Emergency Response Units worldwide were deployed

• The Philippines was also dealing with two prior natural disasters - 7.3 magnitude earthquake a month earlier (October 2013) and Typhoon Bopha in 2012. Together these disasters meant that the Philippines were low on resources - financial, material and human