Lecture 5: Land use, pressure and degradation: can cities solve the problem

Question 1

Options for small subsistence farmers

Answer 1

1. Remain in rural area
   Try to stop degradation and raise yields (hard, but possible – cf. Part 2)
   Find extra income: e.g. artisanal mining (cf. lectures Anouk Borst)
2. International Migration
   High cost, high risk
   Lose social capital (family, culture, homeland)
   Often no skills for destination country
   New country may be hostile
3. Rural-rural migration
   May lower land pressure temporarily
   Often just moves the problem
   Can bring same issues as international migration
4. Rural-urban migration
   Move to capital or major cities
   Pulled by jobs in secondary/tertiary sector, better lifestyle

Question 2

Rural-urban migration

Answer 2

A major process
* Most global population growth = urban
* Mainly due to rural-urban migration (not fertility)
* Cities in Global South growing rapidly
* Trend will continue for decades

Who migrates? (Uganda study)
* Kampala + secondary cities grew via rural-urban migration
* Survey: 1015 rural households in Ankola region
* Reasons to migrate: no land, no work, education, start business
* Poorest farmers (low education, few options) often stay

Question 3

Urbanisation and development

Answer 3

Does urbanisation reduce poverty?
Countries with higher urbanisation = wealthier
Possible reasons: denser activity, shorter trade, use of human capital, shared infrastructure, labour division
But: correlation ≠ causation
Urbanisation as development driver: hard to prove empirically

Does it reduce land pressure?
Sometimes, yes
Global North examples:
→ Drôme valley (SE France): forest came back
→ Indiana, USA: reforestation from 1920 to 1980

Question 4

The forest transition

Answer 4

What is it?
A shift in population–forest relation: from deforestation to reforestation
Causes:
Rural-urban migration + shift to secondary/tertiary sectors
Escape Malthusian trap
Agricultural intensification
Mountain protection
Less wood used (alt. fuels)
More imports (wood, food – cf. Part 0, 2)

In the Global South?
Still mostly deforestation
But trend slowly reversing in some areas
Uganda evidence
Out-migration →
↑ forest plantations, cropland, urban area
↓ wetlands, rangelands, natural forests
Method

Estimate out-migration likelihood per area (based on local conditions)
Compare with land cover changes (Ankola region)
Out-migration correlates better with changes than population density

Why?
Wood is valuable; plantations = income (cf. Part 2: more people → more trees)
Remittances allow land investment
Migration encourages this trend

Conclusion
The speed of forest transition is critical for Global South and beyond

Question 5

Challenges of urbanisation: potential drawbacks of out-migration

Answer 5

Not all forests equal: plantations ≠ biodiversity-rich natural forests
Out-migration = loss of rural human capital
→ Better-off families migrate and invest in e.g. plantations
Incentive: high-revenue, low-labour farming
→ May compete with food production

Question 6

Challenges of urbanisation: Increased pressure on the land

Answer 6

Urbanisation = wealth increase + changing diets (cf. Part 2)
Cities expand into fertile land
Replacement land is less productive
→ Need 2–6× more land to compensate
Urbanisation → indirect land conversion to cropland

Question 7

Challenges of urbanisation: Increased pressure on natural resources

Answer 7

Urban growth = more demand for sand (for cement, concrete, glass)
→ River sand preferred (angularity, location)
Sand = most mined global resource
Local sand mining = rural income source
But: risk of shortages, conflict, river ecosystem damage

Question 8

Challenges of urbanisation: Exploding cities

Answer 8

Unequal city growth
In Global North: 2nd city ≈ ½ size of 1st, 3rd ≈ ⅓, etc. (Christaller’s theory)
In Global South: capital cities grow fastest
→ E.g. Kampala: outpaces secondary cities
In many SSA countries: ≥25% population in largest city

Urban Heat Island (UHI)
Cities = warmer than surroundings
Combined with climate change → more heat stress
1991–2021: 9 of 50 deadliest disasters = heatwaves
→ Only 1 in Global South → Why?

Kinshasa case
+7 million (2000–2020), ~1000/day
Urban area expanded via self-built housing
→ Leads to traffic issues, poverty, poor living conditions
2018: 53% of SSA urban population lived in slums
→ Lacking water, sanitation, space, or durable housing

Question 9

Challenges of urbanisation: (Natural) disasters

Answer 9

Increased risk
High-density, poorly built cities = high disaster risk
Climate change may worsen this
Funu landslide (Bukavu)
Urbanisation altered slope hydrology
→ Changed infiltration and water flow
→ Accelerated landslide movement

Question 10

Case study: urban gullies

Answer 10

What are they?
Runoff forms deep erosion channels in soil
Caused by: erodible soil, steep slopes, intense rain, poor vegetation
Urbanisation adds: hard surfaces, poor drainage, road runoff → more gullies
Examples
Kolwezi (March 2023), Kikwit (2013–2019), Kinshasa (Nov. 2019)
Once formed, gullies keep growing
Destroy infrastructure and displace people

In DR Congo
≥26 cities affected
Kinshasa: >860 gullies
Total: ~3000 mapped; >500 ha
140,000 people displaced in 19 years
Rate increasing
Hidden costs
Lower property values
High stress
Locals try to stabilise gullies, often fail
Risks will grow with population and climate change (cf. Part 1)
Possible solutions

Urban planning: map and avoid risk zones
Urban infrastructure: drainage, canalisation (e.g. Kinshasa)
Broader-scale solution

Alternative migration option:
→ Move to secondary city

Shorter distance → keep social ties
Help develop rural surroundings
Slows down capital city expansion