Physical geography: processes, budgets and risk
Shared geographical foundations
This chapter reviews shared geographical concepts and interpretation of supplied evidence. It does not establish the syllabus, administrative rules, current policy, language or difficulty of a particular examination.
Core rules and concepts
- Relief as a system: endogenic structure (uplift, subsidence, salt tectonics in the North German Basin) sets the frame; exogenic processes (glacial and periglacial sculpture, fluvial erosion, marine abrasion, aeolian transport) shape it. The North German Plain is a young glacial landscape: ground and end moraines, outwash plains (Sander), glacial valleys (Urstromtäler), and Geschiebemergel till control drainage and soil texture.
- Water balance: P = ET + R + ΔS (precipitation = evapotranspiration + runoff + storage change). Actual evapotranspiration is limited by available water; potential evapotranspiration describes demand under reference conditions and depends on radiation and atmospheric factors. A positive climatic water balance means P > PET; a negative one means a deficit that must be met from soil storage or irrigation. Sandy outwash soils have low field capacity, so deficits hit faster even where annual P is adequate.
- Soil formation factors (Jenny): climate, organisms, relief, parent material, time; plus human influence. Acidic organic inputs, leaching and suitable parent material can support podzolisation. Sandy substrates and calcareous till can produce different soil developments, but parent material alone does not uniquely determine a soil class. Gley and pseudogley record waterlogging versus perched water.
- Hazards as risk: Risk depends on hazard, exposure and vulnerability; a product is a conceptual model unless a specific quantitative convention is supplied. Physical probability alone is not an answer; you must name who or what is exposed and why vulnerability differs (building standards, warning systems, land use on floodplains).
Worked example with reasoning
Task: explain why a low-lying North Sea coastal area with rising sea level needs more than higher dikes. Reasoning chain: (1) a supplied sea-level-rise scenario changes the water-level baseline, while any change in storm statistics needs separate evidence; (2) subsidence from peat oxidation and groundwater withdrawal raises relative sea level; (3) higher external water levels can restrict gravity drainage, so taller dikes alone do not solve drainage and pumping needs; (4) therefore adaptation combines dike reinforcement, retention areas (Polder), managed realignment (de-poldering to rebuild marsh as wave attenuation), and land-use restriction in the most exposed zones. Conclusion ties risk components together rather than claiming "dikes are the solution".
Traps that cost marks
- Naming processes without the controlling variables (grain size, slope, vegetation cover, permafrost).
- Using potential evapotranspiration as if it were real water loss.
- Describing soils by colour instead of by diagnostic processes.
- Confusing hazard magnitude with disaster impact.
- Ignoring timescales: a glacial landform and a storm surge operate on completely different clocks.