1. Introduction

1. Introduction

Global warming is causing ice caps to melt. Many of the coastal cities are in danger of being submerged. If the climate continues to warm along current trends, a minimum of 373 ± 21 mm of sea-level rise over the next 100 years is expected from glaciers and ice caps. [Sea-level rise from glaciers and ice caps: A lower bound, 2009]

The effects and aftermath of floods can be devastating. Buildings, vehicles, livestock, crops and infrastructure can get damaged. Loss of lives, injuries, damage to heritage sites, loss of transportation and legal costs associated with lawsuits, just to name a few. For example, the Mekong Delta in Vietnam is affected by the rising sea level, causing implications to the rice production there. [Sea Level Rise Affecting the Vietnamese Mekong Delta: Water Elevation in the Flood Season and Implications for Rice Production, 2004]

This figure above shows the Global wetland losses due to sea-level rise and coastal protection in thousands of square kilometres under the four SRES worlds (A1FI, A2, B1, B2) for the 2020s, 2050s and 2080s. The losses in the 15 most impacted countries are distinguished. [Impacts and responses to sea-level rise: a global analysis of the SRES scenarios over the twenty-first century, 2006] A1FI, A2, B1 and B2 are scenarios predicted by the Special Report on Emission Scenarios world’s (SRES). All of the predicted scenarios show catastrophic losses in wetland due to rising sea levels.

Small and densely populated, the Netherlands is one of the countries most at risk from climate change and rising sea levels. One Dutch construction company, Dura Vermeer, has developed homes that can float with rising waters. Thirty-seven of these homes line the waterfront at Maasbommel, panelled in blue, yellow and green. They have a hollow concrete cube at the base to give them buoyancy. The next time the Meuse river bursts its banks, the house will rise with it (see video). Electricity and water are pumped in through flexible pipes. In all, the houses can withstand a rise in the water table of up to 13ft. At a starting price of 260,000 euros (£180,000 or $310,000), the houses are not a cheap option, but demand is high. [Floating Eco-Homes In The Netherlands, 2007]

This shows that the houses have good demand but is not a cheap option for people to consider.

Our project is about constructing and developing a mechanism that will help houses in rural/urban areas to withstand flash floods or water disasters more effectively. Some criteria we look for in our house is as follows:

Some of the needs of the house include:

1. Make the house rise up with the rising water
2. Prevent the water from going inside the house
3. Protect the house from small debris.
4. Make the house rise itself at the speed of water level rise to protect it from water damage and flooding. For example, a usual flood rises at 3.6km/h [Is flow velocity a significant parameter in flood damage modelling?, 2009]  We aim to make our house match this rate of rise.
In many less developed countries, the cost of constructing a disaster-proof home  is unaffordable to villagers and people. However, we aim to construct a cheap mechanism that meets our criteria for the ensured safety of people living in rural areas.

1.1 Problem being addressed

Many of the coastal cities are in danger of being submerged. In New York City, USA by the mid-2020s, sea level rise around Manhattan and Long Island could be up to 10in, assuming the rapid melting of polar ice sheets continues. By 2050, sea-rise could reach 2.5ft and more than 4.5ft by 2080 under the same conditions. In such a scenario, many of the tunnels - subway, highway, and rail. Some transport systems could be out of operation for up to a month. [The Guardian, 2011]  Cities like London, Mumbai and San Francisco are also bound to be affected

Even though there are many floating houses on the  market. Many of the houses are still expensive, hard to maintain and not customisable. For example, in Netherlands, there are many homes for sale along the coastline that has the ability to float.  At a starting price of 260,000 euros (£180,000 or $310,000), the houses are not a cheap option, but demand is high. [Floating Eco-Homes In The Netherlands, 2007] The houses use new technologies like steel reinforced concrete that do not rust. These are hard to replace if damaged, thus increasing the overall cost of maintaining the house
Our aim is to make a house that is cheap, customisable to a person’s need and meets our criteria (shown below)  at protecting the house.  

Some of the needs of the house include:

1. Make the house rise up with the rising water
2. Prevent the water from going inside the house
3. Protect the house from small debris.
4. Make the house rise itself at the speed of water level rise to protect it from water damage and flooding. For example, a usual flood rises at 3.6km/h [Is flow velocity a significant parameter in flood damage modelling?, 2009]  We aim to make our house match this rate of rise.


The Intergovernmental Panel on Climate Change said in 2007 that sea levels would rise between seven and 23 inches (18 and 59 centimeters) this century, but a rate of ice-melt in the Arctic that is much faster than anticipated has prompted many scientists to raise the projection to about one meter, more than three feet. Among those most threatened are the Marshall Islands, halfway between Hawaii and Papua New Guinea. The highest point on the 29 atolls and five islands is 33 feet (10 meters) above sea level. The capital, Majuro, is just three feet above sea level and was inundated by high tides four years ago.  [CNN, 2012]
Thus our house addresses the global problem of rising sea level causing floods.



1.2 Engineering Goals

Making an efficient mechanism to protect homes from floods and rising sea levels by rising up the house in accordance to the water level. It must meet the specific requirements show in 1.3. It must be able to rise up within the 3.6km/h rate of rise a Level 5 flood occurs at. It should be able to protect itself from small debris like rocks or branches that get swept away in a flood. It also should be made of cheap materials that can be easily obtained like PVC pipes or foam.



1.3 Specific Requirements

Some of the needs of the house include:

1. Make the house rise up with the rising water
2. Prevent the water from going inside the house
3. Protect the house from small debris.
4. Make the house rise itself at the speed of water level rise to protect it from water damage and flooding. For example, a usual flood rises at 3.6km/h [Is flow velocity a significant parameter in flood damage modelling?, 2009]  We aim to make our house match this rate of rise.



1.4 Design Solutions


1.4.1 Design 1



Pros:

  1. High Stability
  2. Low cost
  3. High reliability

Cons:

  1. Vulnerability to debris



1.4.2 Design 2




Pros:

  1. Reduces movement of the house (objects in the house do not fall)

Cons:

  1. High Cost
  2. Low reliability
  3. Unfeasible in real life
  4. Centre of gravity of building restricts design




1.4.3 Design 3




       Pros:

  1. Multiple houses can be chained together

Cons:

  1. Low structural integrity
  2. Poor view / looks bad
  3. Low speed of rise
  4. Vulnerability to debris


Thus we chose design 1 because of its higher number of pros and lower number of cons



1.4.4 Decision making matrix
Table 1: The ranking of the decision matrix



1.4.5 Best solution and rationale

Decision making grid
Requirement

Solution 1
Solution 2
Solution 3
Factors
(What we think is most important)
Normalised value
Votes (0 to 3)
Normalised votes
Votes (0 to 5)
Normalised votes
Votes (0 to 5)
Normalised votes
Safety:
0.154
(3.s.f)
3
3/9
2
2/9
2
2/9
Environmental impact:
0.0983
(3.s.f)
3
3/9
2
2/9
2
2/9
Time
0.0940
(3.s.f)
3
3/9
3
3/9
3
3/9
Total points


1

7/9

7/9
Table 2: The decision making matrix for the 3 most important factors.

From the decision matrix, we have chosen the 3 most important factors by voting. They are, safety, environmental impact and time. We choose safety as it is an important factors in building a structure. If it is not safe, the structure may cause harm to people using the structure. Next is the environmental impact. We are building a platform which is to overcome floods. We are trying to create something which is able to impact the environment, so it is also very important. Lastly we choose time over aesthetics, because we felt that time is more important even though they have the same normalised values. If the structure can be done quickly, people will be able to start using it faster.
After the votes, we have choose structure 1 as our best structure. It has the highest normalised values out of the 3 of them.