Flooding

Question 1

What is flooding?

Answer 1

Flooding is when there is a sudden increase in water in the river and the drainage system can’t handle the increase. This is when flooding occurs.

Question 2

What is storm duration?

Answer 2

Storm duration is when water seeps into the soil quite slowly and so during heavy rainfall, it quickly becomes saturated. Usually, the soil has no time to recover which means the rainwater will run off the surface of the ground and causes flooding.

Question 3

What are stationary storms?

Answer 3

Stationary storms are when a storm becomes trapped over one area and it releases all the rainwater there, a flood is likely to occur.

Question 4

What is the Effect of Field Clearance?

Answer 4

If trees and hedges are removed, they can not suck up any rain. This may lead to a flood.

Question 5

What is the Effect of Roads and Buildings?

Answer 5

Rain can not sink into pavements which may cause flooding.

Question 6

What is the Effect of Ice and Snow?

Answer 6

In upland areas, many millions of litres of water are held in ice and snow. If the temperature rises (for example, in Spring or before a volcanic eruption), the ice and snow will melt and cause flooding.

Question 7

What is the Effect of Rock Types?

Answer 7

Permeable rock allows water through, e.g. limestone, chalk. Impermeable rock does not allow water through, e.g. granite. Impermeable rocks are more likely to cause flooding.

Question 8

What causes flooding? Give 6.

Answer 8

Heavy or Prolonged Rainfall;
Infiltration (ability to soak up water) slows down;
The ground becomes very wet and soon saturated;
The water can no longer go into the ground so it spills as a puddle;
Water finds its way to a river;
The river gets too full and spills onto the land.

Question 9

What can contribute to flooding? Give 6.

Answer 9

Impermeable Rock;
Steep slopes;
Tributaries;
Built-up areas;
Loss of trees;
The flat flood plain

Question 10

List the three Climatic Reasons.

Answer 10

Heavy rainfall over a short or long period of time;
Ground saturated from previous rainfall;
Melting snow and glaciers.

Question 11

List the three Physical Reasons.

Answer 11

Narrow steep-sided valley causing surface run-off to reach the river rapidly after a storm;
Small drainage basin causing rapid surface runoff;
Impermeable rock causing rapid surface runoff.

Question 12

List the four Human reasons.

Answer 12

Urbanisation leading to increasing in tarmac and drains causing rapid surface runoff;
Deforestation in drainage basin leading to less water taken up by roots;
Siltation due to deforestation;
Diversion of river or narrowing of the channel

Question 13

List the effects of flooding.

Answer 13

Buildings washed away or damaged;
People and animals would drown;
Providing fertile soil for farming;
Drinking water contaminated;
Communications damaged;
Crops would get ruined;
Insurance claimed;
Silt deposited

Question 14

What could we do for flood control?

Answer 14

Construction of dams to control discharge;
Construction of levees and dykes to contain water;
Straightening of meanders to remove flood water quickly;
Afforestation to increase interception, transpiration and infiltration;
Sandbagging to prevent flooding of buildings