Architecture and Planning

Urban floods: Drowning of Indian megacities

In recent years, Indian cities start facing urban flood during monsoon season. Every year from July to august many parts of the Indian region face the flood and other impacts from it. In the western region state of Gujarat and Maharashtra, eastern states like Bihar, West Bengal, Odisha, Assam and eastern part of Uttar Pradesh and in southern states like Karnataka and Kerala have faced the floods. Bihar is the most vulnerable state in all of them. In the year 2017, Rajasthan followed by West Bengal, and Bihar are amongst top three states affects in terms of land areas while Bihar is a topmost state in terms of population affected i.e. approximately 17.2 million followed by west Bengal having 8.7 million (https://data.gov.in/resources/stateut-wise-damages-caused-floods-across-country-data-available-central-water-commission).There is a significant increase in urban flooding in India. Urban flooding is different from Natural flooding.

The major cause of urban flooding is the increase in population and unplanned urbanization. Construction activities in low lying area and interference in catchment areas and floodplains change the course of natural drainage routes is a major concern. Urban flooding is typically characterized by

1. Increase in flood peaks by 2-8 times;

2. Increase in flood volumes by up to 6 times;

3. Decrease in time required to reach flood peak;

4. Excessive economic losses (in the form of damage to property and loss of productivity)

Cities	Flooding Years
Ahmedabad	2001
Bangalore	2005, 2009, and 2013
Chennai	2004 and 2015
Delhi	2002, 2003, 2009, 2010, 2013, 2016
Guwahati	2010 and 2011
Hyderabad	2000, 2001,2002, 2006 and 2008
Jamshedpur	2008
Kolkata	2007 and 2013
Mumbai	2005, 2007, and 2015
Srinagar	1992, 2014 and 2015
Surat	2006 and 2013

Source: https://smartnet.niua.org/sites/default/files/resources/FS%203_Urban%20Flooding.pdf

For the intensity of rainfall of 12-20 mm, stormwater drainage systems were previously designed. When higher intensity rain has been received, these capacities have failed very quickly. Furthermore, because of inadequate maintenance systems very often do not work at the designed capacities. Accommodations started to flourish into urban communities by rivers and bodies of water. This resulted in an increase in water flow proportional to watershed urbanization. To accommodate the greater flows of stormwater, the natural drains should ideally have been broadened. As a result, the capacity of natural drains was diminished, and flooding occurred. Improper management and dumping of construction waste to drains of solid waste, including domestic, commercial, and industrial waste, also significantly contributes to the reduction in capacity. Better operations and maintenance measures are absolutely crucial.

Floodwater surrounds the premises of Aluva Siva Temple, Kochi

The Chennai International Airport runway was also built directly over the river Adyar. Most of the airport was built on the riverine floodplains, which resulted in massive flooding during the Chennai floods in 2015. Similarly, developments such as the Amaravati Capital City Project of Andhra Pradesh had proposed that large areas be developed on the Krishna River floodplains.

Urban flood Impacts:

1. Traffic jams

2. Damage to public and private property

3. Mixing of solid waste in floodwaters causing further choking of drains

4. Vector and waterborne disease

5. In coastal cities, increased inundation of low lying areas during high tide reduced capacity of drains to discharge stormwater

6. Disruption of power supply and telecommunication

7. Mixing of fecal matter in the flood water due to open defecation

Responsibilities and Challenges

The reality is that our big cities were built with hardly any regard for the natural topography and there is seriously a lack of integrative initiative. Also, with regulations on rainwater harvesting, sustainable urban drainage systems, etc., in regulatory systems such as the Environmental Impact Assessment (EIA), Notification 2006 or almost every state's building bylaws, adoption at the end of the user and local law enforcement remains a problem. Cities such as Mumbai suffer from a substandard urban infrastructure issue, as they have organically expanded its boundaries over the years. In recent years, Gurugram has seen an exponential growth of both the urban population and the infrastructure. Throughout the year's water bodies and wetlands have declined as a consequence of inadequate planning, unchecked development, and mismanagement of natural resources. From 644 in 1956, the number of bodies of water fell to 123 in 2018. Green coverage is just 9%, which would preferably have been at least 33%.

Measures to tackle urban flooding:

· National Disaster Management (NDMA) Guidelines: In 2010, NDMA had issued guidelines on Urban Flood Management in India -to create a National Hydro-meteorological Network for providing early warning, use of Doppler Weather Radars to be expanded to cover all urban areas in the country, an inventory of the existing stormwater drainage system to be prepared, economic loss, etc.

· Rainwater harvesting and other check measures: on-channel storage of rainwater in storm drains, artificial recharge trenches, retention basins, deepening of ponds and lakes etc.

· Sustainable usage of land: Low-lying areas in cities have to be reserved for parks and other low-impact human activities, restrict encroachments in natural drainage areas; clearance of river beds, proper implementation of Coastal Regulation Zone rules. Planting drought resistant and flood-resistant sturdy trees in vulnerable areas also help.

· Utilizing international best practices: Implementing ‘Mobile Walls’ like in Germany, and ‘sponge’ cities in line with cities in China which involves replacing concrete pavements with porous pavements to ensure better filtration.

CONCLUSION

Lack of planning vision and expansion of cities to accumulate population moving towards them without proper infrastructure has induced the demand for sewage and stormwater management strategy in urban areas. Unorganized development on flood plains and natural wetlands leading to flash fools during monsoon season in India every year. Lack of integrated flood control strategy and lackadaisical attitude of local governing bodies have contributed to the urban flood. Policymakers, planners must learn from the growing case of slood in Indian cities and must prepare various plans at different levels to successfully mitigate and reduce the impact of floods for everyone.

COURTYARD IN INDIAN CONTEXT

BRIEF HISTORY

The origin of the Indian courtyard houses can be traced back to the Indus Valley civilisation. In the course of a moment, climate and society have always affected houses of distinct types. In hot areas, buildings with inner courtyards are regarded as the most suitable. The design of the Courtyard had emerged in Egypt, Iran and China as far back as 3000 BC. The first courtyard homes seemed likely to have come from India around 6500-6000 BC according to historical proof. If we evaluate different cultures carefully, we can understand that courtyard structures are components of Chinese, Japanese and Spanish societies. The change from public to personal courts was made by influencing diverse cultures. The introduction of the Islamic Rulers (14th century) to northern India introduced the main question of dealing with an open room in the country. The British arrival resulted in a significant shift in architectural styles and the courtyard idea (18th century).

REFLECTION FROM SOCIETY

In India, courtyards were not just a type of architecture. They seemed to have been a way of life. Courtyards represented the time's culture and regulated the house's personality and mood. Courtyards had a formal or influential impact on the house's configuration. They assisted individuals to adapt to the summer highs and the Indian subcontinent's cold temperatures.

Modern-day courtyard house
Copyright@ Richard Barnes

Courtyards have various titles such as Kerala's nalukettu (the main courtyard encircled by chambers), Rajasthan's haveli, Gujarat's Wada houses, Ahmedabad's poles, Goa's traditional houses, etc. The design of Kerala's traditional (tharavadu) buildings was easy and intended to accommodate a big number of individuals living in a common household scheme. Each design has arrangements for adequate sunshine and great ventilation has occurred in some well-designed nalukettus. The temperature would be pleasant throughout the year keeping cool in summer and warmer in the winter. The traditional tharavadu's architecture accommodated many individuals residing under one roof and enjoying the homestead's widely shared comforts. The courtyards in Kerala's traditional households put the sacred thulasithara (an elevated platform for tulsi) apart as a prominent location.

Traditional Courtyard Home

There are many courtyards in Central India's houses. The first courtyard is called the baithak (the place of standing). Another is close to the women's area called the inner courtyard. These courtyards have beautiful façades and wealthy design element variants. What is intriguing is that these courtyards not only describe the ideal spatial organization of those moments but also behave as centers for ceremonies, weddings, celebrations, and cultural gatherings. This demonstrates that the courtyard homes develop from the idea of constructing a house around a big room.

RELEVANCE

Despite the successful use of courtyard design over the centuries the notion now seems to disappear as compact construction drawings take priority. The impact of Western society, shifts in lifestyle, and the contemporary equipment accessible on the market have rendered it possible for individuals to offer their houses a contemporary look, often disturbing the environment. Because of economic reasons, the architecture of the old days cannot be reproduced now. Every inch of land is now expensive, so we can't construct enormous buildings with courtyards. Indeed, many hotels, households, farms, etc. are now closely recreating courtyards. More and more planners are now searching at methods to bring courtyards that can play a vital part in the rural and regional growth of today's housing.

A courtyard in a house in inhabited regions can provide a family with a break from the daily bustle and a secure location for kids to play. Architects are experimenting with courtyards with room at a price as a manner to provide living room for tiny groups of people. A courtyard encircled by at least ten buildings would provide a park-like room for those households who would also take pleasure in owning the room. Nevertheless, in the sense of development where ecological problems are of paramount significance, courtyards can still be regarded as a significant component of the architecture that acts both as a social space and as something that decreases the building's carbon footprint.

After the invasion of both Mughal and British there is a dramatic change in the design of houses as factors of land availability, reduced plot sizes, affordability, and development of gated communities have replaced the way home design used to be earlier. The courtyard is trying to make a comeback in theme among the upper crust, though sometimes with artificial grass. New features have been added such as hanging gardens, green walls, and cascading bodies of water to make it more appealing to its residents. Modern architects play a major role in this regeneration, where multi-level courtyards across the magnificent mansions are becoming not only a trend but an emblem of profundity and a design driver as the courtyard significantly enhances the Livability and spaces can be arranged around everything, with a dramatic play of light and shadow.

Sketch view of a Traditional courtyard
Creator@Ar.SuhridPal

Benefits :

Sufficient open spaces for light and ventilation
Maintains a pleasant interior atmosphere throughout the year.
Energy-efficient as it reduces the dependency on ACs and other light requirements.
Provides spaces for cultural gathering and events.
Best suited for larger families.

Limitations :

Requires a large land area.
Challenges affordability.
Construction costs can be higher.

1. Thermal Performance

Courtyard form, proportions, scale, emphasis, building materials, landscape elements, and opening design that opens on to any of it, the inner spaces that surround it, and the housing cluster surrounding it merge to form the thermal capacity of the courtyard home.

2. Shape of Building

Geometry and orientation of the courtyard affect the thermal efficiency of the house. Courtyard orientation (or thermal efficiency) is regulated by Annual and seasonal Thermal variation, Solar orientation.

3. Aspect Ratio

Aspect Ratio (AR) is defined as “the degree of openness to the sky”. Therefore, the greater the aspect ratio, the more exposed the courtyard is to the sky. This factor is considered for the daylight and is calculated as.

Aspect ratio = area of the courtyard floor/(average height of the surrounding walls)^2

If the courtyard is wide and shallow (high aspect ratio), it performs as the sun collector. On the other hand, the narrow and deep courtyard (low aspect ratio) performs as a sun protector, in which orientation has a weak effect on the house.

4. Surface Area to Volume Ratio

Surface Area to Volume Ratio is an indication of the rate at which the building heats up during the day and cools down at night. This ratio is obtained by dividing the total surface of the building including facades and roofs by their volume.

Surface Area to Volume Ratio= Total Surface Area of Building/Volume of Building

In the summer, a higher proportion results in greater heat gain and in winter heat loss. A high ratio also provides a significant raise in the ventilation potential and daylight, which could counter the enormous surface area drawback.

5. Solar Access and Shading

The solar performance of the courtyard depends upon solar access and shading achieved in the courtyard. A shady courtyard in winter may turn up to an open courtyard in summer due to a change in the altitude angle of the sun.

6. The Solar Shadow Index

The Solar Shadow Index (SSI) is a factor that deals with winter sun exposure. The greater the solar shadow index, the deeper the wall formed by the courtyard, and thus the less winter sun reaches the floor or the south wall.

Solar Shadow Index = (South wall height)/(North-South floor width)

7. Natural Ventilation

The ventilation and air movement through the courtyard is determined by prevailing wind direction, average wind velocity, and position and size of fenestrations.

In this enclosed space, air circulation depends mainly on the ratios of the walls and window placement in the rooms in the proximity. The appropriate ratio of the courtyard building offers a cool airflow inside the house it helps in create Comfortable living and sleeping conditions during the day throughout the night. Courtyard temperature, daylight, and air can be monitored in the rooms surrounding it movement. Orientation, profundity, and height are all In order to maintain the same values.

The airflow and natural lighting can be achieved in two ways which affect the thermal comfort of the residents.

Temperature-generated pressure differences (stack effect)

Based on the fact that hot air rises and exits through the top opening, and cool air replaces it. Stack effect phenomena are caused by the pressure difference between the outer air and the air inside structure induced through temperature variation.

Wind-generated pressure differences (cross ventilation)

where air travels from the openings across space. During the day, the courtyard heats up quickly, which enhances the stack effect due to high air temperature differences. However, this happens when the outside temperature is cooler than inside.

8. Thermal Mass

Thermal mass is a concept in building design that describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect. When outside temperatures are fluctuating throughout the day, a large thermal mass of a house can serve to "flatten out" the daily temperature fluctuations. Thermal admittance: Thermal admittance quantifies a material's ability to absorb and release heat from space as the indoor temperature changes through a period of time. Admittance values can be a useful tool in assessing heat flows into and out of thermal storage. Admittance is measured in W/(m2K). So that

h = NQ / A x NT

Where: h = heat transfer coefficient, W/(m2K)

NQ = heat input or heat lost, W

A = heat transfer surface, m2

NT = difference in temperature between the solid surface and the

adjacent air space.

Higher admittance values indicate higher thermal mass.

Architecture and Planning

Urban floods: Drowning of Indian megacities

Cities

Flooding Years

COURTYARD IN INDIAN CONTEXT

1. Thermal Performance

2. Shape of Building

Aspect Ratio (AR) is defined as “the degree of openness to the sky”. Therefore, the greater the aspect ratio, the more exposed the courtyard is to the sky. This factor is considered for the daylight and is calculated as.

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