Urban Areas (DP IB Environmental Systems & Societies (ESS))

Understanding Urban Areas

What is an urban area?

• An urban area is a built-up environment with:

  • A high population density

  • A large concentration of buildings and man-made infrastructure

• Urban areas serve as centres for residential, cultural, economic, trade and social activities

• Cities, towns and suburbs are examples of urban areas

• Urban areas contrast with rural areas

  • Rural areas have:

    • Lower population densities

    • More dispersed settlements, often focused on agriculture and natural landscapes

  • For example, London, UK, is a large urban area with dense population, infrastructure and cultural hubs whereas the Lake District in the UK is a rural area with scattered villages and a focus on agriculture and tourism

Urban ecosystems

• Urban ecosystems are unique environments found within cities and towns

  • They occur where human activities interact with natural elements like plants, animals and climate

• These ecosystems have both biotic components (living organisms like plants, animals and humans) and abiotic components (non-living parts like soil, water, air and urban infrastructure).

Types of urban ecosystems

• Residential gardens:

  • Gardens found in residential areas are important urban ecosystems, providing habitats for plants, birds, insects and small mammals

  • These areas also help to improve air quality and reduce the effects of urban heat islands

• Industrial sites:

  • Industrial areas include factories, warehouses and other business operations

  • These areas may cause pollution, but some are now being redeveloped with green spaces to improve the environment

• Inner-city derelict land:

  • Abandoned or derelict land in cities can become important for wildlife and urban regeneration projects

  • These areas often develop biodiversity as nature reclaims the land

• Green areas and open spaces:

  • Urban parks and green spaces are essential ecosystems, offering habitats for animals, improving air quality and providing recreational space for people

• Traffic corridors:

  • Areas alongside roads and railways form their own ecosystems, with hardy plants and animals that can survive in polluted or disturbed environments

  • Urban planners can design green corridors along these routes to help connect different wildlife habitats within cities

• Cemeteries:

  • Cemeteries are often quiet, green spaces within urban areas that support a wide range of plant and animal life

  • They can act as biodiversity hotspots, with trees, grass and other vegetation supporting birds, insects and small mammals

• Waste disposal areas:

  • Landfills and waste treatment plants are part of urban ecosystems

  • Although they can cause pollution, they are also home to certain species of birds, insects and bacteria that thrive in waste environments

• Forests, fields and water bodies:

  • Some urban areas contain patches of forests, fields, lakes or rivers, which provide crucial habitats for wildlife and help with urban temperature regulation

Components of urban ecosystems

• Biotic components:

  • Plants (trees, shrubs, grass) found in parks, gardens and along streets

  • Animals such as birds, insects and mammals

  • Humans, whose activities like construction, gardening and commuting shape the ecosystem

  • Microorganisms, including bacteria and fungi that break down waste and enrich soil

• Abiotic components:

  • Soil: essential for plant growth in urban parks and gardens

  • Water: found in rivers, lakes and urban infrastructure like water supply systems

  • Air: clean air is important for health but urban areas often face challenges with air pollution

  • Climate: urban areas often create a microclimate, with higher temperatures due to buildings and infrastructure

  • Urban infrastructure: buildings, roads, bridges and other structures are integral to urban ecosystems, affecting how people and nature interact

Urban Systems

• An urban system is a network of interconnected elements that work together to support life in a city or town

• Urban systems involve:

  • Buildings

  • Transport

  • Power and energy supply

  • Water supply

  • Sewage systems

  • Plants and animals

  • Humans

Components of urban systems

Buildings and infrastructure

• Buildings form the core of an urban system, providing residential, commercial and industrial spaces

• Infrastructure such as roads, bridges and utilities (electricity, water and waste) connects and supports the functioning of the urban area

Transport

• Urban areas rely on transport systems like roads, railways and buses to move people and goods

• Efficient transport systems are essential to reduce traffic congestion and air pollution

  • For example, London’s Underground is a major part of the city's urban transport system, helping to reduce road traffic

Power and energy

• Urban systems require energy to power homes, businesses and industries

  • This energy can come from fossil fuels, nuclear power or renewable sources

  • Ensuring a reliable and sustainable energy supply is vital for cities to function properly

Water and sewage

• Water supply systems provide clean water for drinking, washing and other daily needs

• Sewage systems remove and treat wastewater to prevent pollution and maintain hygiene

Microclimate

• Cities create their own microclimates

  • They often become warmer than surrounding rural areas (urban heat island effect)

  • This is due to the high concentration of human activities and infrastructure

• Urban planners consider green spaces and certain building designs and materials to manage urban microclimates

Humans, plants and animals

• Urban systems support human populations, as well as urban wildlife and plants in parks, gardens and green areas

  • These living (biotic) components of urban ecosystems provide recreational spaces and contribute to air quality and biodiversity

Other factors in urban systems

Urban waste and pollution

• Cities generate large amounts of waste and pollution, including solid waste, air pollution and water contamination

  • Managing waste and reducing pollution is critical to maintaining urban efficiency and public health

Urban efficiency

• Urban efficiency refers to how well a city uses its resources, including energy, water and transport systems

  • More efficient urban systems can reduce waste, cut down pollution and improve quality of life for residents

Urban sustainability

• Sustainability is about ensuring that urban systems can meet the needs of the present without harming future generations

  • Sustainable cities focus on reducing their environmental impact by using renewable energy, reducing waste and promoting green spaces

• Urban systems can operate with different types of resource management

  • They might follow either a linear or circular metabolism approach, which affects sustainability and waste management in cities

  • Linear metabolism cities:

    • These are cities that follow a 'take, use, dispose' approach

    • Resources (like energy and water) are used once and then discarded as waste

    • This leads to high levels of consumption and pollution

  • Circular metabolism cities:

    • These are cities that focus on recycling, reusing, and reducing waste

    • This approach aims to minimise resource use by creating a closed-loop system where outputs (like waste) are reused as inputs (e.g. recycling materials or generating energy from waste)

Urban resilience

• Resilience refers to a city's ability to recover from challenges like natural disasters, climate change or economic crises

  • Resilient urban systems have strong infrastructure, emergency services and disaster preparedness plans

  • For example, after Hurricane Katrina (2005), the city of New Orleans, USA, improved its flood defences and urban infrastructure to increase resilience against future disasters

Urban system flow diagram

• An urban system can be represented using a systems flow diagram by showing how resources (inputs) move through the city, are used, and generate outputs like waste and pollution

1. Inputs: the resources a city needs to function

   • Examples: energy (electricity, fuel), water, food, goods (materials for buildings and infrastructure), and labour (human workforce)

2. Processes: how the city uses these inputs in its daily operations

   • Examples: buildings, transport systems, services (healthcare, education), and infrastructure (roads, power plants, water supply)

3. Outputs: the results of urban processes, often in the form of waste

   • Examples: solid domestic waste (rubbish, recycling), pollution (air and water), and sewage

4. Feedback: information or actions that help the system improve in efficiency, sustainability, and resilience

   • Examples: urban planning decisions (like building more green spaces), implementing renewable energy, and waste management initiatives

Awaiting image: Urban system flow diagram

Image caption: Cities of different types, as well as other urban systems such as towns or industrial sites, can be represented using system flow diagrams