Last lesson you watched the Pays de Gex fill up: 309 hectares of farmland, forest and natural land built on between 2011 and 2021, as people moved out from Geneva into what used to be villages. Most of that growth happened one house and one building permit at a time. Nobody sat down and drew it.
This lesson asks what happens when somebody does. First you will look at what a growing city does to the land, rivers and water around it. Then you will meet the people whose job is to decide how land and buildings are used, and follow three of their decisions: turning an industrial district in the middle of Geneva into a new neighbourhood, greening a desert city on the Gulf, and growing meadows on the roofs of Basel.
<aside> <img src="/icons/leaf_green.svg" alt="/icons/leaf_green.svg" width="40px" />
8.2.7 The expansion of urban and suburban systems results in changes to the environment.
Include loss of agricultural land, forests or other natural ecosystems, changes to water quality, river flows and air pollution.
</aside>
In French: switch on subtitles in the settings and auto-translate them into English if you need to. [16 February 2023]
Land. Every hectare a city spreads over was something else first. In the Pays de Gex, the 309 hectares built on between 2011 and 2021 were farmland, forest and natural land [Source]. Fields that grew food and woods that held soil and wildlife became roads, car parks and houses.
Sealed ground and river flows. About two-thirds of the ground in the City of Geneva is now sealed: covered by roofs, asphalt and concrete that water cannot soak through [Source]. On open ground, much of the rain from a storm infiltrates the soil and reaches streams slowly, through the ground. On sealed ground it becomes surface run-off: it races off roofs and roads into drains and straight into the nearest stream. The same storm now arrives in the river faster and all at once, so the peak flow is higher and floods are more likely. Less water soaks in to refill the groundwater below. The canton of Geneva reports that the peak flows of its small urban and suburban streams are tending to rise [Source].
Water quality. Runoff from roads and roofs carries oil, rubber from tyres, metals and salt into streams, a diffuse source of pollution you met with Geneva Airport in Topic 4. More people also means more wastewater to treat.
The River Aire. The Aire flows from France into the canton and joins the Rhône on the edge of the city. In the early 1900s it was straightened to make the land around it easier to farm: its meanders were removed, its banks concreted and its bed fixed by a series of weirs. The straight channel sped floodwater up and concentrated it, threatening the built-up area downstream, and the water quality fell so far that fishing and swimming were banned from the 1980s [Source] [Source]. Since 2002 the canton has given more than 4.5 km of the river a new, natural bed, work that won the Council of Europe's Landscape Award in 2019. Planning can damage a river; it can also repair one.
Air. A bigger city also burns more fuel for traffic and heating, which changes the air its people breathe. You will study urban air pollution in its own lesson, population.3.1.
Task 1.1
<aside> <img src="/icons/leaf_green.svg" alt="/icons/leaf_green.svg" width="40px" />
8.2.8 Urban planning helps decide on the best way to use land and buildings.
Urban planning aims to meet the physical, domestic, environmental, commercial, industrial, financial and health needs of all stakeholders in the community.
</aside>
In French: switch on subtitles in the settings and auto-translate them into English if you need to. [1 May 2025]
Urban planning is deciding how land and buildings should be used: where homes, workplaces, roads, parks and services go, how dense they are, and who pays. Planners have to balance the needs of every stakeholder, and the IB guide names seven kinds:
Praille-Acacias-Vernets (PAV) is about 230 hectares of railway freight yards, warehouses, workshops, garages and an army barracks on the south side of the City of Geneva, beside the River Arve. In June 2011 the cantonal parliament voted to turn this working industrial zone into a dense new district of homes, workplaces and parks [Source]. The plan now aims for [Source]:
The Fondation PAV, a public foundation, holds about 60% of the building rights. The companies already working on the site have to be found new premises before their land can be rebuilt.
Task 2.1 Complete the table for PAV. The first row is done for you.
| Need | A stakeholder who has it | How PAV meets it, or what it costs them |
|---|---|---|
| Physical | People who will commute in and out | 20 km of cycle paths; new streets replace freight yards |
| Domestic | ||
| Environmental | ||
| Commercial | ||
| Industrial | ||
| Financial | ||
| Health |
Task 2.2 Explain one conflict between the needs of two different stakeholders at PAV.
<aside> <img src="/icons/leaf_green.svg" alt="/icons/leaf_green.svg" width="40px" />
8.2.9 Modern urban planning may involve considering the sustainability of the urban system.
Consider factors including quality and affordable housing, integrated public transport systems, green spaces, security, education and employment, use of renewable resources, reuse and recycling of waste, energy efficiency, involvement of the community, green buildings. Include one example of sustainable urban planning, such as the Cerdà plan in Barcelona (1860), the Hausmann plan for Paris (1850s), Brasilia (1960), the controversial Forest City in Malaysia, reduction or removal of car use (Copenhagen), EV charging stations (San Francisco), water conservation (Dubai green space irrigated with grey water).
Application of skills: Investigate maps that show the urban development of a city over time.
</aside>