5. River Hazards & Opportunities

What are the main causes of river flooding?

Rivers flood when water reaches bankfull discharge and overspills onto floodplain

• Heavy, torrential rain → overland flow → flooding

• Prolonged steady rain → saturated ground → overland flow → flooding

• Other natural causes landslides, snow/ice melt, storm surges

How can humans increase the risk of river flooding?

• Urbanisation → more impermeable surfaces

• Deforestation → less interception, more runoff

• Bridges/dams → alter river flow

• Agriculture → soil compaction, reduced infiltration

• Human-induced climate change → more extreme rainfall

What are the hazards of river flooding and erosion?

1. Health risks: waterborne diseases (cholera), mosquito breeding

2. Deaths/injuries in populated floodplains

3. Damage to bridges & transport routes

4. Bank erosion: loss of farmland, housing, transport

5. Destruction of crops, higher insurance, lower house prices

What opportunities do rivers provide?

1. Fertile silt → good for crops

2. Source of food

3. Flat floodplains → easier construction/transport

4. Irrigation of farmland

5. Leisure & tourism

6. Hydroelectricity generation

7. Transport of goods & people