Rivers: Human Causes of Flooding - Rural land use

Question 1

Rural land use:

Answer 1

• Forestry = Interception reduction = Channel capacity
• Farming = Loss of hedgerows = Furrows channel water
• Disappearing fields = New housing = Factory farming

Question 2

Forestry:

Answer 2

• Felling trees = Chopping them down
• Reduces interception = Roots do not absorb water
• After felling = Soil is rapidly saturated, run off occurs and discharge increases rapidly.
• Exposed soil washes into the river = Channel capacity is reduced which leads to flooding.

Question 3

Farming:

Answer 3

• Hedgerows pulled up for big field arable farming = Planting crops
• Loss of hedgerows = less interception.
• Intensive arable farming = less pastoral farming (animals)
• Arable farming leaves field fallow over winter = bare soil equals less interception
• Furrows ploughed up and down hills= water flows easily down hill

Question 4

Disappearing fields:

Answer 4

• Fields intercept rainfall = infiltration soaks up excess water
• Fields sold to property developers = new houses built
• Factory farming = huge shed and concrete yards
• Over grazing compacts soil = Surface runoff increased causing flooding
• Extend growing seasons = grow under polythene.

Question 5

Explain why a change from pastoral to arable farming increases the risk of flooding:

Answer 5

Arable farms sometimes have greenhouses to grow their crops. The water runs off the roofs of the greenhouses meaning there is no interception. Therefore, the water rapidly runs off to the river causing it to rise more quickly. Arable farming also leads to hedgerows being cut down for the tractors to have space. This also means there is no interception and the surface run off increases. This increases the groundwater flow leading to a risk of flooding. Furrows result in water easily flowing downhill causing flooding.