The bullet points below show the main points needed to answer a question similar to that shown. The example of the Mississippi area has been used.
Question:
“People who live near rivers may suffer from river flooding. Explain the causes of this river flooding and how people have tried to prevent flooding of this area happening again.”
Answer:
Causes:
- Very large drainage basin – many tributaries flowing into main Mississippi River at similar area
- Ground was heavily saturated due to previous heavy rain so there was more of overland flow
- Deforestation – more water in rivers due to increased overland flow – more sediment build up – higher risk of flooding
- Many people lived in the “Lower Course” that is meant to flood – this accounts for high fatalities
What has been done to overcome these problems:
- Dams have been built to hold back water during times of flooding for it to be released when the water level goes down
- Spillways – these overflow channels greatly reduce flooding
- The planting of trees by the Tennessee Valley Authority reduced surface run off
- The river was straightened in some areas so that excess rain fall in the river is discharged as quickly as possible