Sustainability, Land Use and Ecological Footprints

When describing a satellite image in an exam, follow these step-by-step visual checks:

• First, check the density: Locate the tightest cluster of buildings with almost no visible ground or green space. This represents the Central Business District (CBD). You may also see long shadows, indicating high-rise vertical growth to maximize high land values.
• Then, analyze the street patterns: Look for rigid, parallel "grid-iron" street patterns. This indicates the Inner City, which contains high-density terraced housing or large apartment blocks built over old industrial sites.
• Next, look for green space and road shapes: Search for areas with curvier, winding roads and cul-de-sacs. The presence of visible private gardens (green patches) and lower building density identifies the Suburbs, designed to reduce through-traffic.
• Finally, locate the city edge: Find the Rural-Urban Fringe by looking for a mix of greenfield farmland and very low-density developments. Look for large white or metallic rectangular roofs (retail or business parks) surrounded by vast grey tarmac car parks, usually next to wide, high-speed motorways acting as buffer zones.

Calculating the Ecological Footprint

If everyone on the planet lived like the average UK resident, we would need 3.1 Earths to survive.

• An Ecological Footprint measures the biologically productive land and water required to produce the resources a population consumes and to absorb its waste (specifically carbon dioxide).
• It is measured in Global Hectares (gha), which represents a hectare of land with world-average biological productivity.
• A city enters an Ecological Deficit when its footprint exceeds the regional Biocapacity (the ability of the area to generate resources and absorb waste).

The footprint calculation involves dividing the total land area required by the population size:

$$\text{Ecological Footprint (gha per person)} = \frac{\text{Total Ecological Footprint (gha)}}{\text{Total Population}}$$

Worked Example

A city requires 4,500,000 gha of land to provide its resources and absorb its waste. The city has a population of 1,500,000 people. Calculate the ecological footprint of the city's residents.

Step 1: Identify the values.

• Total footprint = 4,500,000 gha
• Total population = 1,500,000

Step 2: Substitute into the equation.

• $\text{Ecological Footprint} = \frac{4{,}500{,}000}{1{,}500{,}000}$

Step 3: Calculate.

• $\text{Ecological Footprint} = 3.0$ gha/person

Strategies for Urban Sustainability

A city's success isn't just measured by its wealth, but by how well it balances human needs with environmental limits.

• Urban Sustainability means meeting the needs of the current population without compromising the ability of future generations to meet their own needs.
• Strategies can be large-scale, expensive Top-down Strategies (managed by governments) or smaller, community-led Bottom-up Strategies.

Cities aim to improve the Quality of Life—the general well-being of individuals—through several key strategies:

• Integrated Transport Systems: Cities link different forms of transport to reduce car dependency. London uses the Congestion Charge (£15/day) and the Ultra Low Emission Zone (ULEZ) to deter drivers, while investing £18.9 billion in Crossrail to increase capacity. In emerging cities like Lagos, a Bus Rapid Transit (BRT) system moves 200,000 people daily, bypassing heavy traffic.
• Waste Management: Freiburg in Germany recycles 88% of packaging waste and powers 28,000 homes using an energy-from-waste plant. In Lagos, Wecyclers use cargo bikes to collect waste in exchange for points (a bottom-up approach).
• Urban Greening and Housing: London aims to make 50% of its area green space by 2050. Developments like BedZED in Sutton use 50% less water and 30% less energy than the UK average, utilizing brownfield land and shared "Car Clubs" to reduce emissions.

Evaluating Sustainability and Regeneration

Rebuilding a neglected neighbourhood brings new opportunities, but it often comes at a high social cost.

• Urban Regeneration involves investing capital to revive old urban areas, such as the £9 billion Stratford 2012 Olympics project.
• Pros: Regeneration creates significant economic and environmental benefits. The Stratford project built 10,000 new homes, created 20,000 jobs, and added 10 hectares of parkland. Transport strategies like ULEZ successfully achieved 94% compliance in central London, vastly reducing airborne pollutants.
• Cons: These strategies frequently struggle with social sustainability. In Stratford, over 50% of new rents were unaffordable for original residents, leading to "green gentrification". Similarly, top-down transport fees like ULEZ place a disproportionate financial burden on low-income drivers. Additionally, waste incinerators are often viewed by local communities as eyesores or health risks.
• Concluding Judgement: Overall, while top-down environmental strategies effectively reduce emissions and waste on a large scale, they frequently fail socially by financially burdening or displacing low-income residents. Bottom-up strategies, like the Makoko Floating School (which educated 60 pupils using solar power), offer excellent social inclusion but lack the funding to make a city-wide environmental impact. A truly sustainable city must balance both approaches to protect residents' well-being.