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IB ESS HL 2.1.22 Human Impacts on Stability Questions

Practise IB ESS HL 2.1.22 by evaluating how development and altered sediment flows can push forests and wetlands towards instability.

Syllabus
First assessment 2026
Course
ESS HL
Level
HL

Exam points

  • explain how development pressures cause forest loss through logging, farming, urban growth or pollution
  • evaluate how reduced sediment supply changes delta extent, productivity and habitat

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Study 2.1.22—Human impacts on stability conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB ESS HL 2.1.22 Human Impacts on Stability Questions question 1

[Maximum number: 2]
YearsAverage sediment flow / tons yr^{-1}
1921-196067.5
1971-198041.3
1981-199029.2

Table:Changes to sediment flow into the delta

Table: Changes to sediment flow into the delta: Sediment-flow and Danube-delta maintenance context

Table: Changes to sediment flow into the delta data
• 1921–1960 — average sediment flow: 67.5 tons yr⁻¹.
• 1971–1980 — average sediment flow: 41.3 tons yr⁻¹.
• 1981–1990 — average sediment flow: 29.2 tons yr⁻¹.

The Danube River delta is where the Danube flows into the Black Sea and includes UNESCO Biosphere Reserves and a World Natural Heritage site.
A delta is formed by continuous deposition of sediment carried by the river; sediment adds height and helps it extend into the sea.
The delta is a wetland ecosystem rich in plants, birds and fish, including over 1000 plant species, 300 bird species and endangered sturgeon.
Moldova takes nearly 20% of its water supply requirements from a branch of the Danube.

Suggest what effect this change in the sediment flow would have on the maintenance of the Danube River delta.

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