Hard Engineering, Disadvantages! :D

Hello once again! :D Now for Hard Engineering's disadvantages! :D

No matter how effective/efficient an appliance/structure may be, it will still have it's flaws and that's normal cause nothing is perfect! :)

Seawalls (Hard Engineering)

Seawalls are made to prevent erosion of the coasts, however, a seawall may not protect a coast from erosion in the long run. This is because, when the waves break against the seawall, the energy from the waves is redirected downwards/to the sides of the seawalls resulting in a strong backwash which wears away base/side of the seawall and causing it to weaken and thus, eventually, it will collapse. Hence, seawalls have to be carefully and constantly maintained.


Furthermore, Seawalls are expensive to built! They are estimated to cost 1 million pound(S$3 million) to build a one kilometer stretch of seawall in England.

Groynes (Hard Engineering)

Groyne is a low wall built at right angles to prevent materials from being transported away by the longshore drift as it interrupts water flow and limits the movement of sediments

The disadvantage for groynes is that on the other side of the groyne, the beach will not be replenished by materials carried by the longshore drift thus, the beach further down the coast may erode away. This can lead to cliff collapse and plummeting house prices and destruction of private land in the region making it difficult for affected homeowners to move out.

Also, no matter how useful a series of groynes is to help reduce the effect of coastal erosion, they still spoil the natural beauty of the coastal environment.

Gabions (Hard Engineering)

Gabions, as we all already know is a wire cage containing small rocks to form a wall to protect the coast against erosion and also other coastal structures. However, theses gabions can be easily destroyed by powerful waves that occur during storms. Also, the wires of the cage can rust easily thus, they are easily destroyed.



Furthermore, gabions too destroy the natural beauty of the coastal environment they may take up quite a lot of space up on the beach as lots of gabions are needed to provide plenty of protection. Also, the rocks inside the cage would become worn down and the whole cage would be needed to be taken out and replaced. Plus, if the gabions are stacked up in a wall and a lower one needs replacing this will mean taking out all the ones above it as well before replacing it and rebuilding the wall. this would take lots of time and money! OH, and they have a short lifespan of less then 15 years only! NOT GOOOOD! :(

Okay so that's all the disadvantages of Hard Engineering for coastal protection measures! Soft Engineering would be written by Rosma! :) so stay tuned for her post! :)

Nous aimons la Géographie;
Diyanah

HELLO . (:

hahaha , aunty here to post about soft engineering which involves the application of knowledge of natural processes to stabilise the coast and reduce erosion. Let me break the down into :


1 . Stabilising coastal dunes ( Sand dune stabilisation )

through planting of vegetation which are tolerant to salt spray, strong winds and sand burial. Sand dunes trap sediments washed and blown up, hence slowing the rate of erosion and creating an effective barrier for flood. Footpaths are created so that people won't trample on the vegetation.

Advantages :

• does not disrupt coastline
  
• creates natural habitats for living things
  
• not regarded as unattrative
  

Disadvantages :

• must be thoroughly researched beforehan therefore it will take long periods of time until established
  

2. Beach Nourishment

The process where sediment lost through erosion for example is replaced on a beach. Nourishment material is transported to the affected area.

Disadvantages :

• expensive
  
• (coastal defense scheme) therefore , poorly dedigned project can result in a severely impacted ecosystem regardless of the maintanance.
  
• have to be regularly renourish since nourished beaches tend to erode fater than natural beaches.
  

Advantages :

• reduces storm damage. During storms with elevated water levels and high waves, a wide beach performs as an effective energy absorber with the wave energy dissipated across the surf zone and wide beach rather than impacting on the upland structures and infrastructure

• Recreational benifits . In many coastal areas, the recreational benefits of a wide beach can lifestyle benefits for residents, additional public open space and improved fishing, diving and surfing conditions.

3. Encouraging growth of coral reefs

Coral reefs are actually made of animals! Coral reefs provide protection for harbors and beaches, which are often found behind reefs because the reefs provide natural protection from heavy wave action caused by coastal storms.

4. Planting of mangroves

Its long and curved roots trap sediments and reduce erosion. However, not all coastal regions can support mangroves and coasts may become shallower thus affecting port activities.


Okay , that's just the brief summary ! For more information , we found a web for you where you can understand better about this topic :D , www.slideshare.net/vickikoh/coastal-management-4 . Please watch the video . thank you !

goodnight!



Nous aimons la Géographie; Rosma .

Hard Engineering, Advantages! :D

Hello lovelies! Since i did not really elaborate about the importance of Coastal Protection Measure in my previous post, i shall do it now! :)

Coastal Protection Measures are important because there are some cities, such as Brisbane, Houston and many more which are located along the coast and it is estimated that about 3.6 billion people in the world live along that coast! That's a lot! Also, coasts are awesome locations as tourist attractions! However, as we all know, the coast may sometimes erode thus, affecting people who live near coast they they may need to retreat inland and also affect the infrastructure that has been built. Hence, it is important for us to find way to prevent erosion from occurring :)

There are two different types of measures that could be taken. One, Hard Engineering, and two, Soft Engineering. Hard Engineering refers to the construction of structures such as seawalls, breakwaters, groynes and gabions to protect the coast from erosion while soft engineering involves the application of knowledge of natural processes to stabilize the coast and reduce the erosion.

I will talk more about Hard Engineering in this post :)

Seawall (Hard Engineering)

Seawalls constructed on the inland part of a coast to reduce the effects of strong waves. They are usually made out of concrete, boulders, steel or gabions which absorbs the energy of the waters and protects the coast against strong waves, especially during storms. Also, more modern seawalls tend to be curved so that they are able to reflect the wave energy back out to sea.

Fun, random fact 3.Seawalls can be expensive to build, today costing between $4000 to $7000 per metre (£2000 - £5000 per metre)

Fun, random fact 4. There's going to be a sea wall at Singapore's Resorts World! (picture below)

Also, there are different types of seawalls available! :) here are some examples:

Curved/Stepped seawalls & Standing seawalls

Curved or stepped seawalls are designed to enable waves to break and to dissipate wave energy and repel waves back to the sea. The curve can also prevent the wave overtopping the wall, and provide additional protection for the toe of the wall.

Vertical seawalls are built in particularly exposed situations. These reflect wave energy and under storm conditions standing waves will develop. In some cases piles are placed in front of the wall to lessen wave energy slightly

Rubble Mound

A series of rubble mound-type structures such as riprap and revetment are used in less demanding settings. The least exposed sites involve the lowest-cost bulkheads, or revetments of sand bags or geotextiles. These serve to armour the shore and minimize erosion. They may be either watertight, covering the slope completely, or porous, to allow water to filter through after the wave energy has been dissipated.

Groynes (Hard Engineering)

Groyne is a low wall built at right angles to prevent materials from being transported away by the longshore drift as it interrupts water flow and limits the movement of sediments. All of a groyne may be under water, in which case it is a submerged groyne. The areas between groups of groynes are groyne fields. Groynes are generally made of wood, concrete, or rock piles, and placed in groups. They are often used in tandem with seawalls.

Gabions (Hard Engineering)

Gabions are wire cages that contains small rocks to form a wall to protect the coast against erosion and also to protect other coastal structures such as seawalls. For erosion control, caged riprap is used. For dams or foundation construstion, cylindrical metal structures are used.

Plus, gabions are cheaper alternatives compared to coastal protection measures!


Fun, random fact 5. Gabions are also used in civil engineering, road building and military applications! :)
-In a military context, earth or sand-filled gabions are used to protect artillery crews from enemy fire.

Reinforced earth with gabions, Sveti Rok, Croatia.

Okay! That's all under hard engineering for it's advantages! :D Next post will be for it's disadvantages/limitations! :D

Nous aimons la Géographie;
Diyanah

Simple sweet smiles.

That's them looking really adorable ! :D


OREO !



And them otw to East Coast park !


We're at the top of some tower at Siloso Beach.


Us camwhoring in Sentosa toilet.


With the help of a kind stranger :D


Nous aimons la Géographie; Rosma

Breakwaters!

Okay so since Hazwani has posted about our trip to the three sites which are;
1. East Coast Park
2.Pahlawan Beach
3.Siloso Beach

and took pictures of our visit there plus pictures of breaks waters and other stuffs/measures to prevent coastal erosion, i will post about how each of these measures prevent coastal erosion :)

The most common coastal protection that we found at all the three beaches was the breakwaters. Thus, i will be talking more about this.

Basically, breakwaters (also known as bulkheads) are usually made out of granite and are built parallel to the coast of the beach or built with one end linked to the coast. Breakwaters may be small structures and are designed to protect gently sloping beaches and may either be floating or fixed, depending on the depth of the water and the tidal range.

In Singapore, the breakwaters are mostly built with one end linked to the coast and are fixed. Fun, random fact 1. There are 24 breakwaters at East Coast Park.
Fun, random fact 2. Cost of each breakwater is estimated to be around S$1 million.

Breakwaters prevent coastal erosion by creating a zone of shallow water between itself and the coast, so that the waves will break against it before reaching the coast. This way, there would be an area of slack water behind the breakwaters, thus, reducing the impact of the waves on the coast.

However, no matter how useful breakwaters are at preventing coastal erosion, the processes of erosion and sedimentation cannot be effectively overcome at the same time as deposition of sediment at one site will be compensated for by erosion elsewhere and this phenomenon occurs whenever breakwater or a series of such structures is built along coasts. Thus, there are still some disadvantages of breakwaters.

Breakwaters are unable to provide complete coastal protection as they still leave areas of the coast unprotected due to it's small structure. This will leave the unprotected area to be prone to erosion and gradually shrink, namely due to longshore drift.

Also, over the long term of interfering with currents and the supply of sediment, deposition will occur in these waters and beaches can be built up or extended in these waters and the nearby unprotected sections of the beaches do not receive fresh supplies of sediments.
Futhermore, breakwaters are subject to damage, and over-topping by big storms can lead to problems of drainage of water that gets behind them. The wall also serves to encourage erosion of beach deposits from the foot of the wall and can increase longshore sediment transport.

Okay that's the main idea of how breakwaters prevent coastal erosion and some disadvantages of having them. Now, let's look at some of the different types of breakwaters that's available. :)

Headland Breakwaters

A series of breakwaters constructed in an "attached" fashion to the shoreline and angled in the direction of predominant wave approach such that the shoreline behind the features evolves into a natural "crenulate" or log spiral embayment.

Detached Breakwaters

As the name implies, these are breakwaters that are constructed away from the shoreline, usually a slight distance offshore. They are detached" from the shoreline, and are designed to promote beach deposition on their leeside.

Single Breakwater

Single breakwaters may be attached or detached depending on what they are being designed to protect. A single detached breakwater may protect a small section of shoreline. A single attached breakwater, may be a long structure designed to shelter marinas or harbors from wave action.


Okay! So that's all i'll post about for breakwaters! Will post about the other measures that other countries take to prevent coastal erosion in the next post! so stay tuned! :D

Nous aimons la Géographie; Diyanah