Hello Geographers! Understanding Urban Stress

Welcome to the section focused on the challenges cities face beyond the major topics of climate and waste. Cities are dynamic, but their rapid growth often creates unintended environmental side effects.
This chapter, Other contemporary urban environmental issues, examines four key localized problems: air pollution, water pollution, poor urban drainage, and dereliction.
Understanding these issues, and how they are managed, is crucial for appreciating the goal of creating sustainable cities.

1. Atmospheric Pollution: The Air We Breathe

Urban air pollution is the release of harmful substances into the atmosphere, often concentrating pollutants due to dense populations and heavy traffic/industry.

Key Sources in Contrasting Urban Areas

The source and type of pollution differ significantly between developed countries (HICs) and developing countries (LICs/EICs):

  • HICs (e.g., Western Europe, North America): Focus tends to be on secondary pollutants (pollutants formed when primary pollutants react chemically). The main culprit is vehicle exhaust (NOx, VOCs) leading to photochemical smog (often seen in sunny cities like Los Angeles). Industrial emissions are generally much lower due to strict laws.
  • LICs/EICs (e.g., Rapidly Growing Asian or African cities): Pollution is often far more visible and hazardous, dominated by primary pollutants.
    • Unregulated or older, polluting industries.
    • Use of low-quality fuels (e.g., high-sulfur coal, wood, or diesel) for heating and cooking.
    • High density of older, poorly maintained vehicles.
    • Result: High levels of particulate matter (PM), which is highly dangerous to health.
Impacts on Human Health and Environment

Air pollution directly impacts human health (respiratory diseases like asthma) and damages the urban environment (acid rain can damage buildings and vegetation).

Strategies to Manage Atmospheric Pollution

Cities use a mix of technology, policy, and planning:

  • Policy Controls: Implementing emission standards for vehicles and industries. A major tool in HICs is creating Low Emission Zones (LEZs) or Ultra Low Emission Zones (ULEZs) (e.g., London), where older, polluting vehicles must pay a charge.
  • Transport Strategies: Investing heavily in public transport, cycling infrastructure, and walking areas to reduce private car usage.
  • Renewable Energy: Switching electricity generation from coal/oil to solar/wind, especially in fast-developing economies.

Key Takeaway: Pollution management involves regulating industry and, crucially, changing how urban populations move around and heat their homes.

2. Water Pollution: Keeping Our Rivers Clean

Water pollution occurs when contaminants (chemical, biological, or physical) are introduced into water bodies (rivers, lakes, groundwater) within the urban environment, making them unsafe or harming ecosystems.

Main Sources of Urban Water Contamination
  • Sewage Effluent: In many LICs, a lack of adequate infrastructure means raw or poorly treated sewage flows directly into urban rivers. Even in HICs, old systems can overflow during heavy rain (combined sewer overflows).
  • Industrial Discharge: Factories releasing chemical waste (effluent) into drainage systems or directly into rivers.
  • Surface Runoff: Rainwater flowing over roads and paved areas picks up pollutants like oil, vehicle rubber, heavy metals, and litter, transporting them rapidly into water bodies.
  • Diffuse Pollution: Pollution that comes from a widespread area rather than a single pipe, such as fertilizers and pesticides from urban parks or gardens.
Impacts and Management

Contaminated water can spread diseases (e.g., cholera) and cause eutrophication—excess nutrients (like nitrates from sewage) causing huge algal blooms that deplete oxygen, killing fish and other aquatic life.

Management Strategies:

  1. Wastewater Treatment: Building and upgrading modern sewage treatment plants (STPs) to remove biological and chemical contaminants before discharge. (e.g., Investment in major projects like the Thames Tideway Tunnel in London to prevent sewage overflows).
  2. Regulation and Enforcement: Setting strict water quality standards (e.g., for industrial effluent) and imposing heavy fines for non-compliance.
  3. Education and Community Action: Campaigns to prevent household chemicals and fats from being poured down drains.

Quick Tip: Water pollution is often worse in cities built near natural water sources that were historically used as disposal channels.

3. Urban Drainage and Flooding Issues

Urban drainage refers to the system (both natural and built) used to remove water (precipitation and wastewater) from cities. Inadequate drainage leads to surface water flooding.

The Problem: Too Much Impermeable Surface

Urban development replaces natural soils and vegetation with concrete, tarmac, and roofs. These are impermeable surfaces.

Analogy: Imagine your city is a giant bathtub. Before urbanisation, the water would soak into the soil (the drain). Now, with all the concrete, the drain is plugged. Where does the water go? Overflow!

  • Increased Runoff: Water cannot infiltrate the ground, so it runs quickly over the surface, overwhelming drains and rivers.
  • Shortened Lag Time: The time between peak rainfall and peak river discharge is dramatically reduced, leading to flash flooding.
  • Drainage Capacity: Historic drainage systems were not designed to handle the increased volume and speed of modern urban runoff, exacerbated by climate change leading to more intense storms.
Strategies to Manage Urban Drainage (The SuDS Solution)

The modern solution is Sustainable Urban Drainage Systems (SuDS). These aim to mimic natural processes by managing runoff locally:

  • Permeable Paving: Pavements and car parks that allow water to soak through into a sub-base layer, reducing surface runoff.
  • Green Roofs: Roofs covered in vegetation that intercept rainfall, slow the flow, and promote evaporation.
  • Attenuation Ponds: Small ponds or basins that temporarily store floodwater, releasing it slowly back into the drainage system once the peak flood risk has passed.
  • Wetlands/Swales: Channels lined with vegetation that filter pollutants and slow down water flow.

Key Takeaway: SuDS are a 'soft engineering' approach that manages water quantity and improves water quality simultaneously, promoting sustainability.

4. Dereliction: Wasted Urban Space

Dereliction refers to land that has been abandoned and is no longer being used. This often includes former industrial sites, old railway land, or neglected housing areas.

Causes of Dereliction
  1. Deindustrialisation: In HICs (especially since the mid-20th century), the closure of heavy industries (e.g., steel, shipbuilding, textiles) left huge areas of empty, contaminated factory land (brownfield sites).
  2. Urban Decline and Out-migration: As jobs leave the inner city (decentralisation), populations follow, leading to abandoned shops and houses, especially in older urban core areas.
  3. Lack of Investment: High costs associated with cleaning up contaminated brownfield land often deter developers, making them choose easier, cheaper greenfield sites instead.
Consequences of Dereliction
  • Environmental Damage: Derelict sites can become dumps, allowing pollutants to leach into soil and groundwater. They are often overgrown and unsightly.
  • Social and Economic Impacts: They become eyesores, lower surrounding property values, and can attract anti-social behaviour or crime, contributing to a feeling of decline in the community.
  • Wasted Resource: This land is needed for housing or employment, yet remains unused.
Strategies to Manage Dereliction

The goal is Urban Regeneration—bringing the land back into productive use:

  • Land Remediation: This is the crucial first step for brownfield sites. It involves cleaning up the toxic chemicals and contaminants (like heavy metals or oil residues) left by previous industries. This is expensive but essential.
  • Incentives: Governments offer financial incentives (like tax breaks) to developers who build on brownfield sites rather than greenfield sites.
  • Urban Development Corporations (UDCs): Government bodies tasked specifically with taking over, cleaning up, and marketing derelict land for redevelopment (e.g., the UDC responsible for London Docklands regeneration).

Quick Review: The Four Issues and Their Solutions

| Issue | Primary Challenge | Example of Strategy |

| Atmospheric Pollution | Vehicle emissions, primary pollutants (LICs/EICs) | Ultra Low Emission Zones (ULEZs) |

| Water Pollution | Untreated sewage, industrial effluent | Building Sewage Treatment Plants (STPs) |

| Urban Drainage | Impermeable surfaces, high runoff risk | Sustainable Urban Drainage Systems (SuDS) |

| Dereliction | Abandoned, often contaminated brownfield land | Land Remediation and Regeneration |

Don't worry if this seems tricky at first! Remember that all these issues are interconnected: better land use (avoiding dereliction) reduces runoff and therefore reduces water pollution.