Aqua Cities : Demand for a new habitation by ayushiagrawal

Dissertation On

DEMAND FOR A NEW HABITATION: AQUA CITIES For the degree of Bachelor of Architecture In

SUNDERDEEP COLLEGE OF ARCHITECTURE Ghaziabad, Uttar Pradesh

2017-18

Submitted by

AYUSHI AGRAWAL

Under the guidelines Of

AR. SUNNY THAKUR AR. TAPAN GOYAL AR. SAKSHAM GUPTA

CERTIFICATE

This is to certify that the Dissertation titled “DEMAND FOR A NEW HABITATION: AQUA CITIES” submitted by AYUSHI AGRAWAL as a part of 5 years Undergraduate Program in Architecture at SUNDERDEEP COLLEGE OF ARCHITECTURE is a record of bonafide work carried out by her under our guidance. The content included in the Dissertation has not been submitted to any other University or institution for accord of any other degree or diploma.

Ar. Sunny Thakur (Dissertation Guide)

Ar. Rakesh Sapra (Director)

Ar. Tapan Goyal (Dissertation Guide)

Ar. Saksham Gupta (Dissertation Guide)

ACKNOWLEDGEMENT

While a completed dissertation bears the single name of the student, the process that leads to its completion is always accomplished in combination with the dedicated work of other people. I wish to acknowledge my appreciation to certain people. I shall begin with God the almighty: without His will, I would have never found the right path. His mercy was with me throughout my life and ever more in this study. I thank Him for enlightening my soul with the respected love and compassion for the other humans and allowing me to enter a field where I could practice this desire. I would like to acknowledge my indebtedness and render my warmest thanks to my supervisor, Ar. Sunny Thakur who made this work possible. His friendly guidance and expert advice have been invaluable throughout all stages of the work. I would also wish to express my gratitude to Ar. Saksham Gupta and Ar. Tapan for extended discussions and valuable suggestions, who have contributed greatly to the improvement of the thesis. The person with the greatest indirect contribution to this work is my mother. I want to thank her, my father, as well as my brother and sister, for their constant encouragement.

ABSTRACT

In the past century, living in cities inside the water or beneath it, was an idea only used by film makers in Hollywood to create some interesting science fiction movies. In this century and with the challenges the world is facing, the idea became more and more appealing to architects as a solution to many of their immediate and future problems. To these architects, these cities are expected to be smart, liveable, sustainable and resilient, four concepts any city now strives to achieve. This indicates the importance of such a city and the possibilities it can offer. In addition, the concept of building a complete city in the water, an â&#x20AC;&#x153;Aqua Cityâ&#x20AC;? as the research calls it, is very inspiring and has its own aesthetical values. Thus this dissertation tries to explore the idea of an aqua city and to illustrate its relation with the four concepts and their principles.

TABLE OF CONTENTS 1. Introduction………………………………………………………………8-11 1.1 Aim……………………………………………………………………………….8 1.2 Objective………………………………………………………………………….8 1.3 Scope ……………………………………………………………………………..8 1.4 Limitation…………………………………………………………………………9 1.5 Future Problems………………………………………………………………….10 1.6 Background Study………………………………………………………………..10

2. Literature review………………………………………………………..12-25 2.1 Aqua Cities………………………………………………………………………12 2.1.1 Four main aspects to an Aqua City……………………………………….12 2.1.2 Types of Aqua City……………………………………………………….13 2.2 Design of Underwater Structures…………………………………………….......17 2.2.1 Project Type………………………………………………………............18 2.2.2 Shape and Form………………………………………………………..….18 2.2.3 Degree of Enclosure………………………………………………………19 2.2.4 Entrance Spaces and Access……………………………………………....20 2.2.5 Dependency of Structure………………………………………………….21 2.2.6 Safety…………………………………………………………………...…22 2.2.7 Selection of Site……………………………………………………...……22 2.2.8 Lighting……………………………………………………………….…..23 2.2.9 Use of Color……………………………………………………………....23 2.2.10 Construction and Assembling…………………………………………….23 2.3 Materials Used………………………………………………………………...…24 2.4 Construction Techniques…………………………………………………...……25 3. Case Study……………………………………………………………………...26-37 3.1 Ocean Spiral, Japan………………………………………………………………26 3.2 Lady Landfill Skyscraper, Southern Chile…………………………………….…33 3.3 Gyre, Ocean City………………………………………………………….……..35

4. Design Objectives…………………………………………………….....38-47 4.1 Energy from the Ocean………………………………………………………..…38 4.2 Underwater Mining……………………………………………………………....42 4.3 Monitoring Seismic Activities………………………………………………...…44 4.4 Movability………………………………………………………………………..45 4.5 Safety………………………………………………………………………….....45 4.6 Structure, Cost and Economics………………………………………………..…46 4.7 Advantages………………………………………………………………….……46 4.8 Disadvantages……………………………………………………………………47

5. Conclusion and Recommendations………………………………………..48 6. Bibliography……………………………………………………………...…49

LIST OF FIGURES Figure 1 Aqua City................................................................................................................................ 12 Figure 2 Floating Ecotopia city, Japan.................................................................................................. 13 Figure 3 Lilypad City, Dubai ................................................................................................................ 14 Figure 4 Ocean Spiral, Japan ................................................................................................................ 14 Figure 5 Floating City Project, Pacific Ocean ...................................................................................... 15 Figure 6 Lilypad City, Dubai ................................................................................................................ 15 Figure 7 Water Scraper, Malaysia......................................................................................................... 15 Figure 8 Floating Island, South Korea .................................................................................................. 16 Figure 9 Floating Ecotopia City, Japan ................................................................................................. 16 Figure 10 The Ark, China ..................................................................................................................... 16 Figure 11 Shapes according to pressure................................................................................................ 18 Figure 12 Pressure on the walls ............................................................................................................ 19 Figure 13 Entrance through horizontal tunnels ..................................................................................... 20 Figure 14 Entrance through vertical tunnels ......................................................................................... 21 Figure 15 Steel used Underwater .......................................................................................................... 24 Figure 16 Aluminium alloys ................................................................................................................. 24 Figure 17 Titanium alloys ..................................................................................................................... 24 Figure 18 Ocean Spiral ......................................................................................................................... 26 Figure 19 Base Camp-Ocean Spiral ...................................................................................................... 26 Figure 20 Green Concept Tower........................................................................................................... 26 Figure 21 Lifestyle in Ocean Spiral ...................................................................................................... 27 Figure 22 Central Tower comprising of Business Zone ....................................................................... 27 Figure 23 Infra Spiral ............................................................................................................................ 27 Figure 24 Earth Factory ........................................................................................................................ 28 Figure 25 Spherical concrete lattice shell of 500m in diameter ............................................................ 28 Figure 26 Using an internal tower to reinforce the sphereâ&#x20AC;&#x2122;s shell ........................................................ 28 Figure 27 Spherical shell with triangular acrylic plates measuring 50m on each side ......................... 28 Figure 28 360Â° panoramic views of the deep sea.................................................................................. 28 Figure 29 Construction techniques ....................................................................................................... 29 Figure 30 Submersion of completed structure ...................................................................................... 29 Figure 31 Ocean Spiral construction method ........................................................................................ 30 Figure 32 Floating seawall .................................................................................................................... 30 Figure 33 Vibration Damping equipment ............................................................................................. 30 Figure 34 Site Variations ...................................................................................................................... 30 Figure 36 Candidate sites based on sea floor topography ..................................................................... 31 Figure 35 Sites based on regional characteristics ................................................................................. 31 Figure 37 500-m diameter (city model) ................................................................................................ 31 Figure 38 200-m diameter (architectural model) ................................................................................. 32 Figure 39 Five basic elements............................................................................................................... 32 Figure 40 Gyre, Australia ..................................................................................................................... 33 Figure 41 Extended wings to afloat the structure.................................................................................. 33 Figure 42 Circulation between vortex and breakwater elements .......................................................... 34 Figure 43 Design Concept- Lady Landfill Seascraper .......................................................................... 35 Figure 44 Cross sections ....................................................................................................................... 36 Figure 46 Garbage collecting units ....................................................................................................... 37 Figure 45 Vertical Program .................................................................................................................. 37 Figure 47 Typical tidal power plant ...................................................................................................... 38 Figure 48 Tidal power generation ......................................................................................................... 38 Figure 49 Pontoons floating on sea bed ................................................................................................ 39 6

Figure 50 Oscillating Water Column .................................................................................................... 39 Figure 51 Wave power .......................................................................................................................... 40 Figure 52 Ocean Thermal Energy Diagram .......................................................................................... 40 Figure 53 Block diagram of all applications from OTECT .................................................................. 41 Figure 54 Ocean Thermal Energy Conversion...................................................................................... 41 Figure 55 Mining Deposits ................................................................................................................... 42 Figure 56 Extraction of ores from sea bed ............................................................................................ 43

1. INTRODUCTION: LTHOUGH technology was introduced into all areas of life in answer to current and future economic, social, and environmental problems. However, as a result people managed to alter the world´s climate in a way that it has become a threat to human civilization. Many coastal cities are slowly sinking into the water due to the climate change and the rise in sea level it caused. For example, the edges of Dubai´s most famous holiday resort, the artificial palm island, have already been eroded by floods. Therefore, architects, with futuristic architectural visions, tried to overcome the ongoing global warming with all its damaging consequences through new and unconventional architecture. One of these contemporary futuristic concepts invented by revolutionary architects and designers are “Aqua Cities”, an innovative and imaginative solution to the future environmental problems. It is also a new trend that aims at using the ocean/sea space, an approach that can result in the human populations’ settlement of the oceans, especially since land became more and more limited in some countries.

1.1 AIM: To study about designing, stability and functionality of Aqua cities.

1.2 OBJECTIVE: To study about the design considerations of underwater structures thereby studying its

Construction techniques



Materials used underwater for its better functionality



Shape and designing of different structures employed in working of an underwater city

1.3 SCOPE: The Aqua cities could be the building block in shaping the future of next generation. With the advanced technology and new techniques, it could be made more stable than the cities already flourished on land. Keeping in mind the imbalance created in the earth’s biosphere by humans it could be made more susceptible to climate change and natural disasters. Also only 1% of seawater has been researched and accordingly sea is home for varied resources. Aqua cities could generate a platform for underwater studies thereby encroachment of new resources for a better future.

1.4 LIMITATION: The study aims to define the architectural parameters thereby limiting it to engineering basics.

1.5 FUTURE PROBLEMS It is estimated that only one-eighth of the surface of the earth is suitable for humans to live on. And roughly three-quarters of the earth surface is covered by oceans and water. The rest of the land area (one eight) consists of deserts (14%), high mountains (27%), or other unsuitable terrain. However, there is still plenty of space left on the vast land to build cities or accommodate people for the coming centuries as we are only occupying roughly 5% of the earth surface. So why would we start to live on floating cities on the water surface? Reasons to live on water in the far future is encouraged by the following problems: - Sea level rise due to climate change (intense rainfall) - Lack of available building ground

Sea level rise due to climate change. The ice caps are melting as a result of the higher temperatures and the sea level is expected to rise. A rise of the sea level brings problems to the coast or the sea defences of a country. A rise of the sea level also means a rise in the water level of rivers. Moreover, the climate change brings more severe rainfall, which leads to higher river discharges. The flood defences in a country (especially in a country below the sea level like the Netherlands) are more heavily loaded and need to be improved to minimise the risk of flooding. Instead of fighting against these water issues, one can also adapt to it and live with it. This can be accomplished by floating houses (and to a much bigger extend, floating cities), which are flexible on rising water levels.

Lack of available building ground. The lack of available ground to build houses and facilities on is another problem the society is facing. There is a demand for more living space due to the ever-fast growing population. Some countries/cities do not have that available ground to build houses on, which is why they tend to extend to the sea with the help of land reclamations. But there are places in the world where land reclamation is less feasible. For instance, places where the water depth is too large or places where there is no or scarce sand available for land reclamation works (a well-known example is Singapore). A solution for these places where

land reclamation is less feasible or expensive is, again, to live on the water with help of floating structures. The concept of a floating city is not necessarily needed now, but it would provide more use in the future when sea level rise is really becoming a big problem. It also helps for overpopulated cities (near shores) to expand to the sea.

1.6 BACKGROUND STUDY: Until recently, only marine biologists and underwater archaeologists were the main parties interested to live underwater, since to biologists, to be there, is the only way to understand whatâ&#x20AC;&#x2122;s really happening in the oceanic environment. As for archaeologists, they could resurrect sunken ships or search for lost artefacts. However, lately some architects began to see underwater living as a solution for preserving human kind in case of an apocalyptic catastrophe, a newer version of Noah's ark. On the other hand, major oil companies were the main parties interested in developing water floating platform technology. Most of their platforms have been piercing the ocean surface while resting on the ocean floor. However, lately, the oil companies have started to use free-floating platforms, which do not need to be bottom supported; where the platform can float freely but stays in position by resisting the effects of wind and waves. However, the oil companyâ&#x20AC;&#x2122;s platforms were not the only floating systems that appeared. Table (1) will illustrate the different types of floating systems found nowadays.

Table 1 Current floating structures

Type Floating Bridges

Floating Entertainment Facilities

Nordhordland Floating Bridge, Norway

Floating Restaurant in Yokohoma, Japan

Floating Storage Facilities Floating Oil Storage Base

Kamigoto Floating Oil Storage Base, Nagasaki Prefecture, Japan

Floating Plants

Studies are already underway to use floating structures for wind farms.

Floating docks, piers, berths and container terminals

Floating Airports and Mobile Offshore Base

Floating Cities

Floating Pier at Ujina, Japan

Mega-Float in Tokyo Bay, Japan

Osaka Focus B by Japanese Society of Steel Construction

2. LITERATURE REVIEW 2.1 AQUA CITIES: As aforementioned, many different types of structures have been built in the sea as floating platforms to expand the living space or for functional uses. It started with small structures as illustrated and ended with architects designing offshore floating cities to absorb urban expansion in the years to come, which will be referred to in the research as the “Aqua City”. By 2020, it is expected to establish the first Aqua Floating

City,

with

significant

political autonomy. To the research, an “Aqua City” is the city where its residents live and work permanently on a floating or underwater structure, Figure 1 Aqua City

on offshore shallow waters or on

open-ocean in deep water. The city can be fixated in a certain place or free to move and travels like a ship or a submarine with different promising visions and constructive plans to deal with multiple scenarios. Developed from these visions, the “Aqua city” will be classified into three main types; a floating city, a submersed city and a semi- submersed city.

2.1.1 FOUR MAIN ASPECTS TO AN AQUA CITY: Sustainability followed by liveability than resiliency approaches have replaced the old belief in technology and smart approach only, with its careless consumption of energy and resources, while creating a city. Nowadays, usually the term “liveable city” includes sustainability and resiliency as well, three essential aspects while developing a city; in addition to advanced technological appropriation. This part will illustrate that an aqua city is developed putting all these four aspects in consideration. According to some architects, the temporary or permanent living on the sea can be peaceful, profitable and also luxurious. Since an aqua city uses digital technology and computer controlled systems which can produce various benefits: such as the availability of new services to citizens and commuters, and thus improving the quality of life and developing a smart city. This is considered an answer to the main aim of a liveable city,

which is improving the quality of life for the cityâ&#x20AC;&#x2122;s residents. On the other hand, sustainability is always related to the ability of the city to be maintained and to sustain itself and its resources for many coming centuries for the future generations and residents. And, sustainability of an aqua city is related to an approach that is mainly conscious about the energy, water and ecology of the city. Again, using smart technology in aqua cities can reduce energy and water consumption, hence contributing to CO2 emissions reductions. Harnessing wave action or using solar panels are great sustainable future options used in aqua cities as renewable energy techniques. As for water, enough water could be collected from condensation of precipitation or desalinization, as previously mentioned, to meet the citizens.â&#x20AC;&#x2122;

2.1.2 TYPES OF AQUA CITIES: 1. Floating Aqua City (Above Water City) 2. Semi-Submersed Aqua City (Above & Beneath Water City) 3. Submersed Aqua City (Beneath Water City)

FLOATING AQUA CITY (ABOVE WATER CITY) A Semisubmersible platform designed to house residents mainly above water surface. It is best to be placed near shore in the calm, shallow waters found within territorial seas and bays; however, it can be set in deep water on the open ocean. It can also be fixed in one place or move like a ship.

Example, Floating Ecotopia City (Green Float), Japan Floating ecotopia or green float is a series of floating islands where residents live and work in its eco skyscraper cities. They can also easily get to open space, gardens and the beach above its platform. The islands are connected together and can form a country. Figure 2 Floating Ecotopia city, Japan

SEMI-SUBMERSED AQUA CITY (ABOVE & BENEATH WATER CITY) A Semisubmersible construction designed to house residents above and beneath water surface. It is best to place it in deep water on the open ocean and to move like a ship although it can be found in calm, shallow waters found within territorial seas and be fixed in one place as well. Example, Lilypad City, Dubai Lilypad is an autonomous semisubmersible floating city, providing room for up to 50,000 citizens. It is built so its residents can live and work above and beneath sea level.

Figure 3 Lilypad City, Dubai

SUBMERSED AQUA CITY (BENEATH WATER CITY) A totally submerged construction designed to house residents mainly under water surface. However, in some types, it can have platforms above surface with some services. It is best to place it in deep water on the open ocean and to be fixed in one place although it can be movable like a submarine or ship as well. Example, Ocean Spiral, Japan Ocean Spiral dotted over the ocean that could survive

extreme

weather

events

earthquakes, which are fairly common in Japan. Micro-organisms called methanogens could be used to convert carbon dioxide captured at the surface into methane. Designed to house 2000 residents. Figure 4 Ocean Spiral, Japan

The Application of the Integrated City Principles on various Aqua Cities The Floating City Project, Pacific Ocean Project Application: Enhancing the residence quality of Life 

It is an energy-efficient and self-sufficient city.



It provides economic development to the governing authority. Figure 5 Floating City Project, Pacific Ocean

Lilypad City, Dubai

Project Application: Comprehensive land use

and

green

areas

improved

environmental quality 

Each floating city is designed to sustain

around 50,000 citizens. 

The man-made landscape in it creates a

diverse environment for its citizens. 

It is a zero-emission city.

Figure 6 Lilypad City, Dubai

Water-Scraper, Malaysia Project Application: Efficiency and reservation of resource use 

This city produces its own electricity using wind, wave and solar power.



It also produces its own food through hydroponic

techniques,

farming

and

aquaculture. 

The structure uses a set of squid-like tentacles which generate kinetic energy.

Figure 7 Water Scraper, Malaysia

Floating Island, South Korea Project Application: Satisfying social needs & supporting historical preservation and cities aesthetics 

Great excitement filled the residents living off the Han River in Seoul, South Korea for the world’s largest floating island.



With its entertainment complex, the Viva is drawing crowds and masses.



It provides its own sense of beauty.

Figure 8 Floating Island, South Korea

Floating Ecotopia City , Japan Project Application: Conducting a waste & pollution control management plan 

It manages waste through a waste control

plan. 

Energy is generated from renewable

sources, which decrease pollution. Figure 9 Floating Ecotopia City, Japan

The Ark, China Project Application: Sustainable and resilient infrastructure and systems 

bioclimatic

structure

with

independent life support system. 

Open layout to accommodate different functions over time and allows resiliency of the city.



It uses solar cell & wind turbine, while enough daylight enters through the transparent roof.

Figure 10 The Ark, China

2.2 CRITERIA FOR DESIGNING AN UNDERWATER STRUCTURE Technologies of other fields were utilized by architects to design and construct underwater projects. So far, structures that were constructed for different purposes inspired architects. Moreover, some of the realized projects were produced by engineers who were experienced in submarine and acrylic tunnel design. On the other hand, one of the main objectives of architecture is to provide human a comfortable living area by means of meeting their requirements. Namely, architecture creates spaces for people. This purpose of architecture should be valid in any medium that is say underwater. Therefore, architectural aspects for the design of underwater structures should be taken into consideration and discussed with an indication on their difference from terrestrial ones. In the design of underwater structures, it should be intended to meet a set of design goals for a liveable space. In other words, criteria for a liveable space should be defined and applied according to underwater conditions. These criteria can be listed as: 

Keeping the inside pressure equal to the surface pressure.



Establishing adequate technical systems to meet human comfort.



Meeting all the physiological requirements of occupants.



Providing convenient lighting to the space.



Offering an adequate transportation system to carry people to the structure or proposing suitable entrances according to the whole project.



Offering view to exterior to link interior space with environment.



Ensuring the safety

ARCHITECTURAL DESIGN PARAMETERS FOR UNDERWATER STRUCTURES These parameters can be defined as: 1. Project type. 2. Degree of enclosure. 3. Entrance space and access. 17

4. Dependency of structure (land-depended or autonomous). 5. Safety 6. Selection of site. 7. Lighting. 8. Use of colour. 9. Construction and assembling.

2.2.1 PROJECT TYPE According to the project type underwater structure may be linked with other terrestrial buildings or may be independent. At the first phases of design process, the decisions about the “physical and operational relations” with others parts and shore should be made and all the solutions and required systems should be designed accordingly. Mainly two alternatives can be thought: 

The underwater structure can be a part of complex located on land.



The underwater structure itself can constitute the whole project. In this case, there may be also two alternatives: o All functions can be governed by underwater structure. o There can be a structure over water level that governs other functions.



The two parts (over water and submerged), which have no relation by means of structure can be link with tunnels, travelators or elevators.

2.2.2 STRUCTURE AND STRUCTURES The

biggest

challenge

for

SHAPE

THE

UNDERWATER

underwater structure is withstanding the constant water pressure. The cylinder and sphere are verified as the most common shapes for undersea habitats. Figure 11 Shapes according to pressure

Pressure is a force divided by the area. The force of this pressure is exerted perpendicular to the surface on the object. The illustrations on the left are based on a gas pressure from inside the object, but the principles work the same with water pressure from the outside. Gas pressure is easier to work with because one can assume the gas exerts equal pressure to all sides, while water exerts more pressure on the bottom of the object than on the top, because the pressure is depended on the height of the water column above the object. Forces acting on the outside of the object will cause compression stresses in the material and forces acting on the inside will cause tensile stresses. The wall tension is dependent on the pressure and the radius of the sphere. With an equal pressure the wall tension will increase Figure 12 Pressure on the walls

when the radius is increased.

2.2.3 DEGREE OF ENCLOSURE The space must have a barrier that separates interior and exterior. Barriers can be combined to form an enclosure. Openings, such as windows, doors or view ports, define a link between two separate spaces through barriers. Properties of an opening determine the qualities of space, for instance light, view and degree of enclosure. In the case of underwater structures, the amount of enclosure should be decreased. Certainly, providing maximum transparency and view is a more appropriate approach for the nature of underwater design. Moreover, it can be stated that one of the main objectives of underwater designing should be establishing relations with underwater. â&#x20AC;&#x153;Architecture always depends on things that are already there.â&#x20AC;? Namely, as the problems, the potentials and peculiarities of the environment should be recognized and besides utilized. The submerged structures are able to provide distinctive experiences for people, such as observation of underwater world and integration with the environment. This can be achieved by means of view ports and transparent shell elements. Such openings in structure offer view from the interior space to the exterior in order to establish visual relationships with surrounding. It can be suggested that transparent materials, which have enough strength to resist hydrostatic

pressure, can be preferred to enclose interior space in underwater structures to achieve maximum view and relation with environment.

2.2.4 ENTRANCE SPACE AND ACCESS The way of access to underwater structures and design of entrances places should be considered at the conceptual design phase. Humans can directly reach the entrance space which is under water by â&#x20AC;&#x153;scuba divingâ&#x20AC;?. However desirability of this approach can be questioned, due to the fact that it will not be preferred by visitors. Various alternatives of access can be achieved according to the location of entrance space. Entrance space can be provided on land or over water. First, entrance space can be designed on land. It can be constructed as an individual building or provided in other building of complex. After that the access to the underwater structure will be through horizontal, vertical or inclined tunnels according to the level and locations of the structures. Steps, escalators, ramps or moving platforms can be provided in tunnels . Certainly a second entrance area can be provided under water

Figure 13 Entrance through horizontal tunnels

Secondly, entrance space can be designed over the water level. People can reach this space by motorboats or via a land bridge. Afterwards, the access to the underwater structure can be through vertical tunnels.

Figure 14 Entrance through vertical tunnels

These tunnels can also be used to transport air, power and water from land to the submerged structure. The tunnels can be divided into two parts- technical equipmentâ&#x20AC;&#x2122;s and pipes can be located one section while people move in the other part.

2.2.5 DEPENDENCY

STRUCTURE

(LAND-DEPENDED

AUTONOMOUS) The living conditions in underwater structures should be designed to be similar to those on land. Against environmental conditions architecture suggests systems for human comfort. The following ones should be considered and designed with engineers: First of all, to survive a breathable atmosphere should be achieved. Therefore air supply system (oxygen supplement and removal of carbon dioxide) is essential. Electrical system is vital to survive underwater since all other systems depend on it. The system supplies power for lighting, heating, operation of electrical equipments and appliances. Therefore, uninterrupted electric power should be provided to underwater structures. Mechanical systems are required to provide comfort-zone conditions for occupants. These systems include the heating, cooling, ventilating, and air-conditioning equipments used to control the comfort factors such as air temperature, relative humidity of the air and air motion. These systems may show differences in underwater structures because of the special requirements of an enclosed atmosphere. Water supply is needed for occupancy, climate control, and fire protection. For human consumption and sanitation a potable water supply is essential. System for waste management is another issue that should be provided for collection and removal of waste water and organic waste. The disposal of perishable and non-perishable hard waste from kitchens and rooms should also be taken into consideration. 21

LAND-DEPENDED The structure can be land-depended and typically would have normal air supplied from the surface through a pressure resistant pipe. Likewise, power and water are provided to the structure from the land. Energy, water and air can be distributed in underwater structures via tunnel. If the underwater structure is a part of a complex, the resources of the complex can be shared by the submerged part. In addition, an independent technical unit can be constructed on land, which is linked to city network. Afterward, all necessary equipments for mechanical and electrical systems can be transported from land to submerged structures. Electric power can be transported by “submarine power cables” from land. Similarly, wastes can be transmitted to the land for necessary applications. Electricity can be provided from land through tunnels. However energy storage namely “electric generators” should be positioned under water in emergency conditions. Similar to electric power, although water can be supplied from land storage should be thought in order to deal with the breakdown of the supply system. AUTONOMOUS DEPENDENT Alternatively, the structure can be completely autonomous with its own diesel generators, water makers, satellite communication, sewage treatment plant and other equipment to form a complete, self-contained system anchored off-shore.

2.2.6 SAFETY There might be a crack in the submerged structure caused by an unpredictable event or other problems. Therefore the safety of occupants is vital that must be though and provided in underwater design. Emergency exits and entrance for divers to interfere should be designed. Safety places, as shelter in terrestrial buildings, can be proposed in underwater structures. Small submarines may be placed in critical areas to transfer the people inside the structure to land. For damages which are able to repair on the sea bed the pressure-resistant door, as in the habitats, will be locked automatically.

2.2.7 SELECTION OF SITE In the word the underwater structures are located in special sea beds which contain special underwater flora such as coral reefs and various sea creatures to display them as a scene. Therefore, after decision was made to design an underwater structure required study should be performed through the region where project will be constructed. On the other hand it can be stated that, for beginning the challenge of achieving structures under water may be more significant that the quality of site. From this perspective, initially underwater structures can be constructed as a part of existing buildings without respect to characteristic of sea bed, for example a hotel complex on island or near the sea.

2.2.8 LIGHTING Light is a fundamental element in architecture which serves two primary objectives: illuminating a task and creating a mood. The lighting system should provide sufficient illumination for the performance of visual tasks, such as dining, reading and watching. The sun is a rich source of natural light for the illumination of forms and spaces in architecture. Besides, this daylight has psychological benefits as well as practical utility. However, underwater spaces may not utilize day light as terrestrial ones. Therefore, lighting system should be appropriate to fulfil the requirements of natural light as well. In fact, interior light should be meeting the requirements of comfortable living so that all activities can be carried out like on land without any obstruction.

2.2.9 USE OF COLOR Generally color can be used to emphasize the character of the space or change it. In underwater design color can be utilized to handle the disadvantage of the environment on perception of space quality. Warm colors can be preferred to balance and deal with the cold blue color of the water. The underwater restaurant, red sea star, can be demonstrated as an example for this approach. To balance the bluish aquatic light, a range of color from yellow to orange and red were chosen.

2.2.10 CONSTRUCTION AND ASSEMBLING Architects should be aware of the limitations and potential of the environment. Besides, adequate knowledge about construction and assembling is required. The most appropriate techniques should be utilized. For instance, the structure can be constructed in sections that can 23

be easily transported later assembled on the site and finally submerged. Unrealistic design and requests will cause loss of time and cost. Therefore, architects should contact with the persons experienced in the construction of this type of structure in order to make efficient and appropriate design according to this new environment.

2.3 MATERIALS USED: Steel can be easily welded, bolted and riveted. Welding creates a continuous connection between two steel components. This gives steel great flexibility when it comes to combining different elements to create a certain shape. Welding can also happen under water, but the best quality is achieved in a factory, where the elements are preconstructed. Bolts are often used to connect steel to

Figure 15 Steel used Underwater

other materials, such as wood, but can also be a sustainable choice to allow the structure to be dissembled. Concrete is a mixture of water, cement and an aggregate. This aggregate can be almost any type of sand, gravel, slag or natural stone. Concrete has a high compressive strength, but needs to be combined with steel for a high tensile strength. Concrete can take almost any shape if it is poured into such a mould and left to harden. Aluminium alloys are preferred as a construction material because of their availability, low cost and being easy to fabricate. The main disadvantage of this material is being vulnerable to corrosion when used in mixed structures Figure 16 Aluminium alloys

because of their chemical properties.

Titanium alloys have a better strength/weight ratio than aluminium alloys and are ideal to be used. On the other hand titanium alloys are 5.5 times more expensive than aluminium alloys and it is an important disadvantage for this material. Steel and acrylic plastic are preferred for surfaces.

Figure 17 Titanium alloys

Transparency could be achieved by acrylic plastic which had an extensive use in deep submersible and aquarium applications. 24

Properties of materials used: The materials used in underwater applications primarily should both be capable of withstanding “stress cycles” due to the external pressure and resist to corrosive effects of seawater. 

Good resistance to corrosion



High strength/weight ratio (the wall thickness should not be too large in order not to sink.)



Good sound absorption qualities



Material costs



Fabrication properties (easiness of manufacturing.)



Durability (operating life span of the material.)

To date, steel, aluminium, or titanium are used conventionally in the construction of pressure vessel and “each material has advantages and disadvantages with respect to such factors as corrosion resistance, fatigue, fracture resistance, ductility, and yield strength.

2.4 CONSTRUCTION TECHNIQUES: The caissons and cofferdams are the techniques used for the construction of underwater structures.

Caisson: A caisson is a water-tight box like structure or a chamber, made of wood, steel, or concrete, usually sunk by excavating within it, for the purpose of gaining access to the bed of a stream and placing the foundations at a prescribed depth and which subsequently forms part of the foundation itself. Caissons are adopted when the depth of water is great and the foundations are to be laid under water. Caissons are generally built on the shore and launched into the river floated to the site and sunk at the proper position.

Cofferdams: In an engineering structure, such as a bridge pier, has to be built in an area covered with water, e.g. in the middle of a river, the area where the work has to be done is surrounded by a cofferdam. A cofferdam is well made of earth materials, of steel or timber sheet piling, or a combination of various materials. Under actual working conditions, it is impossible to build a impervious cofferdam and as such there is always some seepage though the cofferdam, and the water has to be pumped out of the working area. Cofferdams are used to protect a working area against a large influx of subsurface water. 25

3. CASE STUDY: 

Ocean Spiral, Japan



Gyre, Australia



Lady Landfill Seascraper, Southern Chile

3.1.

OCEAN SPIRAL

Ocean Spiral dotted over the ocean that could survive extreme weather events like earthquakes, which are fairly common in Japan. Micro-organisms called methanogens could be used to convert carbon dioxide captured at the surface into methane. Estimated cost of the project is approximately $25 billion and, if construction begins soon the first

Figure 18 Ocean Spiral

could be completed by 2030. Each globe would be 1600 ft. in diameter and would have on board hotels, residential area and commercial spaces.

THE OCEAN SPIRAL BASE CAMP Blue Garden is a sphere measuring 500m in diameter that floats in the deep sea like a spaceship.

Figure 19 Base Camp-Ocean Spiral

Figure 20 Green Concept Tower

This city is even safer and more comfortable than the land-based ones. 

A comfortable city with minimal temperature changes



A safe city unaffected by typhoons or earthquakes



A healthy city with higher concentrations of oxygen than on the ground.

A NEW LIFESTYLE In the Casual Zone facing the deep sea, people can experience and enjoy the deep sea, while learning about and discussing its unique qualities. Examples:    

Deep sea sightseeing tours Hands-on education on the deep sea Deep sea high-concentration oxygen therapy Comfortable and safe places to live and work Figure 21 Lifestyle in Ocean Spiral

NEW BUSINESS MODELS The Business Zone of the central tower incubates business models for new deep sea industries. Examples:    

Deep sea resource industries Deep sea energy industries Deep sea tourism industries Advanced deep sea research facilities Figure 22 Central Tower comprising of Business Zone

INFRA SPIRAL Integrating the functions required because of the deep sea  Electricity: Power generation based on ocean thermal energy conversion  Food: Aquaculture using deep sea water  Fresh water: Desalination using water pressure  Transportation: Port (supply base) for deep sea submersible probes  Information: Deep sea monitoring facility Figure 23 Infra Spiral

EARTH FACTORY: Developing tomorrow’s advanced deep sea industries based on today’s up-to-date deep sea research. CO2: Storage and reuse of industrial carbon dioxide emissions Resources: Development and cultivation of deep sea resources Figure 24 Earth Factory

TECHNOLOGY Structural Design: Building a Submerged City of Concrete, 500m in Diameter 

Strength Using a spherical shape to withstand water pressure 

Concrete

High-

strength resin concrete 

Reinforcement bars

Figure 25 Spherical concrete lattice shell of 500m in diameter

Rustproof resin bars 

Environmental considerations Use of materials

recycled from PET beverage containers in the resin concrete Figure 26 Using an internal tower to reinforce the sphere’s shell

Exterior Wall Design: Tackling the Challenge of Building a Transparent Sphere with 360° Panoramic Views of the Deep Sea

Figure 27 Spherical shell with triangular acrylic plates measuring 50m on each side

Figure 28 360° panoramic views of the deep sea



Strength Realized using triangular acrylic plates measuring 50m each a side



Strength Reinforced using semi-transparent FRP ribs



Cleaning Using microbubbles and other means to prevent the adhesion of marine life



Joints Sealing against water, absorbing displacement etc.,

Indoor Environment Design: Challenge to Achieve the Comfortable Environment Making the Best use of the Conditions of the Deep Sea. 1. Natural convection Using temperature differential between the sea water and air to ensure the natural convection with comfortable and cool air 2. Dehumidification Using the cooling source of deep sea water to ensure comfortable dehumidified air conditioning 3. Air conditioning Reusing chilled water after dehumidification to ensure comfortable radiant air conditioning 4. Thermal insulation A comfortable environment due to the insulation effects of acrylic plates (3m thick). Construction Plans: Challenge to Achieve Fully Automated Maritime Construction of the Sphere. Early adoption of future technologies 3D printing construction method (Pouring resin concrete,

resin

bars).

Integrating

proven

technologies. Automated vertical diversion of large-scale concrete forms Jump-up method Balanced

cantilever

Dywidag

method.

Construction methods specific to maritime

Figure 29 Construction techniques

Figure 30 Submersion of completed structure

Figure 31 Ocean Spiral construction method

construction. All construction work undertaken at the sea surface (Submersion of completed structure) Operation and Maintenance Plans: Fail-safe Features and Maintenance. Control of vertical movement: Super ballast balls filled with sand. Wave control: Floating seawall. Control of everyday vibrations: Vibration-damping equipment

Figure 32 Floating seawall

Figure 33 Vibration Damping equipment

VARIATION Compatible with various sites and scales Site Variations: The OCEAN SPIRAL Network, Connecting the Worldâ&#x20AC;&#x2122;s Seas

Figure 34 Site Variations

Candidate sites based on regional characteristics 30

Coastal seas: Stimulating economy on remote islands in exclusive economic zones

Figure 36 Sites based on regional characteristics

Figure 35 Candidate sites based on sea floor topography

Seas of island nations: Countering rising sea levels in Pacific island nations Seas in desert regions: Comfortable deep sea living in the seas of the Middle East and Africa. Scale Variations:

Figure 37 500-m diameter (city model)

Figure 38 200-m diameter (architectural model)

In addition to the city-scaled 500-m diameter model, a more practical architectural-scale 200m diameter model is prepared. SOLUTION Earth regeneration by potentials of the deep sea

Figure 39 Five basic elements

3.2 CASE STUDY 2: GYRE, AUSTRALIA The Gyre is an inverted underwater skyscraper, from depth of 400 m. It would be as tall as 1,312 ft. and would be about the same height as the Empire State Building in New York. The 212,000 square meters structure consists of layering of concentric rings of different sizes, ranging from 30,000 square meters down to 600 square meters. It will harness wind, wave and solar energy. Gyre is meant to be a research station and an off shore resort, replete with gardens, shops and restaurants. Its shape is what is touted to make it a sturdy structure that can

Figure 40 Gyre, Australia

withstand ocean winds. Four arms extend from the centre spire (1.25 kilometres in diameter). They keep the structure afloat and create a harbour large enough to accommodate huge ships. Gyre’s power source is renewable energy, with zero emissions. It has vertical wind turbines on top of the radial arms. Semi-transparent solar windows glaze the entire structure. Solar panels also shade pedestrian walkways on top. Underwater turbines generate power from water currents when anchored. Rainwater gets collected in the central vortex into storage tanks at the spire’s bottom. It has been designed by Victoria BC based firm Zigloo. For a gigantic concept such as this, one only wonders about waste management if it gets functional. Gyre creates a new class of Ecotourism by bringing scientists and vacationers together to understand what is the least known in our environment, the ocean. As much as a skyscraper is an economical method of reducing humankind’s footprint on land, Gyre goes a step further by Figure 41 Extended wings to afloat the structure

juxtaposing that footprint to the ocean 33

and is perhaps its greenest feature. Its unique design permits the simultaneous application of wind, solar, and tidal energy generation technologies thereby making it truly ‘off-grid’. In addition to using vertical axis wind turbines, electrical energy is also collected by solar means. Two applications of solar glazing are used: the first, a semi-transparent solar window is used facing the open-air, inner vortex; the second, a glass with a printed array of solar cells spaced to create partial shading, is used as a solar pergola or roof material. Furthermore,

Figure 42 Circulation between vortex and breakwater elements

underwater nacelle’s function both as tidal generators when the structure is anchored and as thrusters for propulsion when Gyre is under way. The structure manages undersea pressures and stresses by its shape. Rainwater is harvested in the inner vortex and gravity fed to the water purification system at the base of the Gyre. Mechanical systems and emergency freshwater storage basins are in the deepest portion of the structure. The first two levels of the Gyre’s vortex are dedicated to circulation, community gatherings, restaurants and commerce. Intermediate levels accommodate long-term residents, oceanic experts, hotel guests and crew quarters totalling as many as 2000 people. The deepest levels are dedicated to a scientific observatory for oceanographic research and an Interpretive Centre for public discovery of the depths of the ocean.

3.3 CASE STUDY 3: LADY LANDFILL SEASCRAPER The Great Pacific Garbage Patch is a pile of plastic floating in the northern part of the Pacific Ocean. The San Francisco Chronicle claims that the patch now weighs more than 3.5 million tons, 80% of which is plastic waste that reaches more than thirty meters in depth. This area of the Pacific Ocean is a relatively calm region that causes the accumulation of floating

Figure 43 Design Concept- Lady Landfill Seascraper

garbage in big piles. Its removal will cost billions of dollars and no country claims responsibility.

This proposal consists of a series of underwater scrapers, floating islands that will be used to remove and recycle the garbage patch. These are self-sustained structures organized by function hierarchy with four communication cores that connect three main programs â&#x20AC;&#x201C; collectors at the bottom, recycling plant in the middle levels, and housing and recreational levels atop.

Figure 44 Cross sections

Considering that the size of the floating garbage island is constantly varying, the structural organization of the skyscraper should reflect these variations. The main hole in the structure would adjust the mass of the underwater skyscraper while keeping the volume constant. Fluctuations in the amount of trash in the landfill (located in the lower part of the structure) would be adjusted by adding or releasing water, so that the weight to volume ratio is appropriate for floatation.

Figure 46 Vertical Program

Because most of the molecules found in the garbage have high energy, the waste will be heated in the recycling chamber and converted into a gas that will be stored in massive battery like structures.

Figure 45 Garbage collecting units

4. DESIGN OBJECTIVE 4.1 ENERGY FROM THE OCEAN The Earth's oceans could one day provide enough energy to power homes and businesses. Technologies have been developed to harness energy from tides, waves, temperature gradients, ocean currents, ocean winds, and salinity gradients. The three most developed technologies derive energy from tides, waves, and Ocean Thermal Energy Conversion (OTEC) and are described below, Energy from Tides Tidal power is not a new concept, and has been used since the eleventh century in Great Britain and France to turn water wheels. Presently, power is generated from tides in a manner similar to hydroelectric power plants. A barrage (dam) is built across an estuary. Gates and turbines installed at regular intervals along the barrage are opened when there is

significant

difference

water

elevation on either side of the barrage. Water flows through the turbines and Figure 48 Tidal power generation

electricity is produced. This method can

Figure 47 Typical tidal power plant

be used for water flowing both into and out of the estuary. Although tidal power generation can offer some advantages, including reducing greenhouse gas emissions by not using fossil fuels, there are some significant environmental disadvantages. The construction of a tidal barrage in an estuary will change the tidal level in the basin. This change will have a marked effect on the turbidity (cloudiness) of the water and sedimentation within the basin, which in turn affects navigation and recreation. An altered tidal level will also have an effect on the local marine food chain. However, because very few tidal barrages have been built, little is understood about the full impact of tidal power systems on the local environment and it is evident that its effects greatly depend on the local geography and marine ecosystem. Energy from Waves Wave energy generation devices fall into two general classifications: fixed and floating. Fixed generating devices, which are mounted either to the seabed or shore, have some significant advantages over floating systems, particularly in the area of maintenance. However, the number of suitable sites available for fixed devices is limited. The Oscillating Water Column, a fixed device

built

shore,

generates

Figure 49 Pontoons floating on sea bed

electricity in a two-step process. As a wave enters and leaves the column, the water in the column rises and falls, which in turn forces air back and forth through a turbine at the top of the column. This is a very simple device, but it is difficult to build and anchor so that it is able to withstand the roughest sea conditions and yet generate a reasonable amount of power from small waves. Much research is occurring Figure 50 Oscillating Water Column

internationally

develop

oscillating water columns that require less

stringent siting conditions, including the OSPREY, and floating columns, such as the Japanese Mighty Whale. Floating-wave energy devices generate electricity through the harmonic motion of the floating part of the device, and are extremely efficient. In these systems, electricity is generated through the rise and fall of the waves. Examples of fixed devices include the Salter Duck, Clam, and Archimedes wave swing.

Figure 51 Wave power

Energy from Temperature

Figure 52 Ocean Thermal Energy Diagram

Ocean Thermal Energy Conversion (OTEC) utilizes the temperature difference between the warm surface sea water and cold deep ocean water to generate electricity. As long as a sufficient temperature difference (20째C or 68째F) exists between the warm upper layer of water and the cold deep water, net power can be generated. There are three types of OTEC processes: closed-cycle, open-cycle, and hybrid-cycle. In the closed-cycle system, heat transferred from the warm surface sea water causes a "working fluid" (such as ammonia, which boils at a temperature of about 25째C, or 78째F, at atmospheric pressure) to turn to vapor. The expanding vapor drives a turbine attached to a generator that produces electricity. The working fluid passes through a condenser and turns back into a liquid that is then recycled through the system. Figure 53 Block diagram of all applications from OTECT

Open-cycle OTEC uses the warm surface water itself as the working fluid.

The water vaporizes in a near vacuum at surface water temperatures. The expanding water vapor drives a turbine attached to a generator and produces electricity. The water vapor, which has lost its salt and is almost pure fresh water, is condensed back into a liquid by exposure to cold temperatures from deep-ocean water. If the condenser keeps the vapor from direct contact with sea water, the condensed water can be used for

Figure 54 Ocean Thermal Energy Conversion

drinking water, irrigation or aquaculture. A direct contact condenser produces more electricity, but the vapor is mixed with cold sea water and the discharge water is salty and is returned to the ocean. The process is repeated with a continuous supply of warm surface sea water. Hybrid

systems use parts of both open-cycle and closed-cycle systems to optimize production of electricity and fresh water. Aside from the generation of electricity, it has been proposed that OTEC plants assist oceanbased industries, such as aquaculture, refrigeration and air conditioning, desalinated water crop irrigation and consumption, as well as mineral extraction through the use of the fresh and chilled water by-products.

4.2 UNDERWATER MINING Interest has been growing over the last 10â&#x20AC;&#x201C;15 years in exploitation of mineral resources in the deep sea. These are extensive or highly concentrated deposits typically found offshore at depths over 200 m. There are 4 main types of resource that are of current commercial potential. Mining operations. There is not yet any commercial mining activity in the deep sea, and

Figure 55 Mining Deposits

specific operations for each resource type are not definite. The sorts of equipment and methods will differ between the mineral deposits, and also between mining companies. Phosphorite and manganese nodules are likely to be dredged off the seafloor, whereas SMS and cobalt crust extraction involve more rock-cutting technology. In general there are three key components to deep-sea mining operations, irrespective of the mineral. Seafloor operations: Extracting the minerals from the seafloor will involve dredging or cutting the resource. This is where large mining machines will move around on the seafloor. Midwater transport: Dredged or cut material is transported from the seafloor to the surface. This can be as a slurry in riser pipes, or closed bucket-type conveyor systems. 42

Surface processing: The mined material will be sorted and dewatered on the surface vessel. For all types of seabed mining, the filtered wastes and seawater will be returned to the water column-somewhere between the surface and the seafloor.

Figure 56 Extraction of ores from sea bed

MINING IMPACTS There is a wide range of potential environmental impacts from any mining operation. Some of the main ones include: Surface Increased vessel activities and potential pollution and collisions (includes risks associated with extreme weather events). Changes in primary production through shading by, or nutrient levels in, discharges (if near-surface discharges occur in photic zone). Effects on behaviour of surface marine mammals, fish and birds through changes in water composition or clarity, and lighting/ noise from vessel activity.

Water column Sediment plume through water column. Depending on discharge depth potential oxygen depletion - nutrient and trace metal enrichment - change in ocean pH. Effects on deep-diving marine mammals and fish behaviour, from the plume and noise â&#x20AC;˘ Bioaccumulation of toxic metals though the food chain to higher predators. Toxic effects in early life stages (embryos, larvae, juveniles). Plankton/mesopelagic fish mortality and behavioural avoidance of contaminants (e.g., high turbidity, chemically enriched plumes) Seafloor Benthic organism mortality from direct physical impact of mining gear Smothering/burying of animals by deposited sediment. Change in seafloor sediment characteristics post mining (e.g., removal of large particulate material suitable for sessile species and settling of larvae and colonisation). Clogging of suspension feederâ&#x20AC;&#x2122;s feeding structures. Toxic effects with metal release (and other contaminants), and accumulation through the food chain The nature and extent of such impacts are uncertain and need to be evaluated on a case by case basis for each mineral resource type and local conditions where mining is planned.

4.3 MONITORING SEISMIC ACTIVITIES Active volcanism has long been known on the ocean floor: apart from providing the mechanism for sea-floor spreading and the formation of new oceanic crust, it is involved in the subduction process near oceanic trenches, and also at mid-plate locations where, given sufficient activity, it can result in the formation of substantial seamounts or even island chains. Quantitative estimates of this latter form of volcanism have recently been revised upwards following such investigations as BATIZA'S (1982) and the statistical work of JORDAN et al. (1983). However, these estimates have been based entirely on studies of the product of volcanic episodes, namely the morphology of seamounts, as opposed to the direct observation of ongoing volcanic eruptions, as is the case for subaerial volcanoes. As a result, very little is known regarding the present level of volcanic activity in vast areas of the oceanic basins, such as most of the Pacific Ocean.

4.4 MOVABILITY Movability is an essential aspect to aqua city. It is required so the city can move away from a sudden disaster or travel over the seas for any other reasons. The self-propelled option is not cost effective, if the city moved only once in ten years or less, also the disassembly option is not viable since it would take too much time to disassemble. The best feasible options, until now, are moving the floating district by semi-submersible ships or towing the floating district away. Both ways can be used to move large and small structures.

4.5 SAFETY: Securing the safety of the city and its citizens is a major aspect that can have an enormous influence on the design decisions. Safety measures are divided into two parts; first the ability of the cityâ&#x20AC;&#x2122;s structure to survive severe sea conditions in both a protected bay and/or on the high seas. Secondly, the survival of its citizens at ordinary conditions or at times of a disaster. Thus, the safety measures in an aqua city must consider avoiding extreme consequences such as property damage, fatalities or environmental damage. Property damage may occur as a result of a small structural damage, as for fatalities it can occur due to major structural failures such as capsizing, sinking, global structural failure or drift-off. These disasters are mainly a result of environmental hazards such as large waves, storms, or hurricanes. Therefore, it is important for the city to be able to move fast enough to avoid the disaster, with a study of the wind and climate. Another important safety requirement, related to personnel safety, is conducting evacuation and rescue plans. An effective safety plan must provide a safe place for citizens to survive on board before safe escape can take place, in addition to a broad risk analysis approach with multiple possible accident scenarios. It is equally important to the safety of the citizens to provide a reliable stable structure for the city and a living environment where citizens can live and enjoy their life safely. This could mean assuring that underwater residence is running smoothly through observing life support systems, air composition levels, temperature and humidity from above at the surface, and pressures.

4.6 COSTS, STRUCTURE & ECONOMICS According to some people, aqua city technology is not expensive and can be afforded by most countries of the world. However, to the majority, the costs of engineering some designs, that can withstand the ocean's elements; wind, waves and corrosive seawater and at the same time remain comfortable enough to live on permanently in sea, are high Until now, there are two types of huge floating structures (VLFSs) that are being used; the semisubmersible-type and the pontoon-type. The semi-submersible type is raised above the water surface using ballast structural elements or column tubes, in addition to using breakwaters which makes it suitable to deploy in high seas and open-ocean with its large waves. However, according to Delta Sync, the costs of a breakwater are very expensive. Floating oil drilling platforms are great examples of semi-submersible-type. On the other hand, pontoon-type lies on the water surface like a huge plate floating on sea. Pontoon-type floating systems are suitable for use in only calm, shallow waters near the shoreline, which makes it less expensive to engineer compared with structures engineered for the open ocean. Moreover, some architects consider it best to create the city using small structures that could be added or taken away to develop a living space for as many citizens as needed. This can help in the resiliency of the city especially to accommodate the growing population. However, constructing the city in this way using small structures provides less stability in harsh waters, and requires extra engineering requirements for moorings and connections. On the other hand, larger platforms are certainly more stable, but more expensive due to the need to brace it by a taller costly internal structure.

4.7 ADVANTAGES: An Aqua City has many advantages. As urban development grows in land-scarce countries or countries with long coastlines, resorting to aqua city to decrease the existing load on heavilyused land is the best solution, since it creates additional spaces for new cities to ease the overpopulation. Furthermore, living in water is a reasonable solution to the dilemma of environmental collapse since to some experts, it will be less expensive and easier to accomplish than building in space. Aqua city also provides a testing ground for new water, energy and floating technology solutions.It provides freshwater produced using condensation of precipitation or desalinization and energy developed from sunlight by using solar panels and from wind by using wind turbines. In addition, its design can allow it the flexibility to move around the world as submarines or ships or position itself offshore as a fixed structure, 46

providing movability, dynamic geography, water experience and sea keeping. The city that will be constructed offshore or in bays will be easier for its citizens to travel to and from the existing land-city and acquire goods and services when needed. Moreover, fresh seafood is easy to deliver from the bottom of the ocean. However, most of the aqua cities are self-sufficient and can also use the Blue Revolution technology which allows for remediating the environment and high technology food production ways. Finally, one of the main advantages of an aqua city is being a smart, sustainable, liveable and resilient city.

4.8 DISADVANTAGES: One of Aqua City greatest challenges is transnational law since it can support populations large enough to create a new state in itself. In addition, crucial needs such as emergency evacuation systems and environmental controls, used for air supply and humidity, use technological advances that will need high maintenance and observation to avoid their failure. Also cooking underwater, although possible, will be prevented because of the smell it produces, since fumes are felt stronger in static air, unless special technology is found to contradict its effect. Other factors that present challenges are mooring, wave breaking, comfort and costs of the city, which depend greatly on the sea depth, the large waves, tides, winds and storms. The city must also be guarded against disasters especially hurricanes, since if not protected well it can lead to total loss of the city. In addition, a submersed city will face another challenges such as scalding volcanic fluids, ravaging storms and bone-crushing pressures. Thus, it is most likely to build no deeper than 1,000ft (300m), since the pressures at such depths will require building very thick walls in addition to excessive periods of decompression for citizens who needs to return to the surface. However, currently, people who stay in laboratories under the water did not experience any ill effects from staying below the surface for around 60 days. It is believed that living up to six months would be feasible. Finally, one of the main disadvantages of an aqua city is the high costs of some of its visions.

5. CONCLUSION & RECOMMENDATIONS : The dissertation tries to provide a visionary, innovative and revolutionary answer to the expected rise in sea level due to global warming that led to the sinking of the cities in the sea and the scarce in lands to accommodate the growing populations in some countries. In hope that it will cause a debate that leads to a deeper awareness and professional interest in aqua cities between academics and architects, apart from science fiction writers and utopian dreamers. Hence, if the cities should truly be flooded by oceans, people will survive in aqua cities, a city that can travel on all oceans from the equator to the polar-regions in high seas, or stand still on calm offshore water. Unlike what many architects think, an aqua city has many more advantages than its disadvantages. In addition, by using various case studies, an aqua city proved that it can sustain a better way of living by being a sustainable, liveable and resilient city through being a smart one; the four main aspects required achieving while developing any successful city. Certainly there are many fields in which architects have to work upon stating, natural lighting, ventilation etc., that governs the functionality of underwater structures. Additional important aspects that were discussed in relation to an aqua city to prove its applicability are; costs, structure, economics, movability, materials and safety. Finally, although an aqua city might seem now, in some way, ahead of its time, demonstrating a vision of the future that is thought by some likely to be impossible, it can be very applicable and much needed at the near future.

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