River discharge and flooding

Question 1

River discharge

Answer 1

Is the volume of water that flows in a river per second.

Question 2

Hydrographs

Answer 2

Show how the discharge at a certain point in a river changes over time in relation to rainfall.

Question 3

Peak discharge

Answer 3

The highest discharge in the period of time you are looking at.

Question 4

Lag time

Answer 4

The delay between peak rainfall and peak discharge.

Question 5

Rising limb

Answer 5

The increase in river discharge as rainwater flows into the river.

Question 6

Falling limb

Answer 6

The decrease in river discharge as the river returns to its normal level.

Question 7

Floods due physical factors

Answer 7

Prolonged rainfall-long period of rainfall causes the soil to become saturated
Heavy rainfall-the water arrives too rapidly for infiltration
Geology(rock type)-clay soils and rocks are impermeable
Relief- in steep-side valley, the water will reach the river channel faster

Question 8

Floods due human factors

Answer 8

Buildings and roads are made of impermeable materials. This increases the runoff of rainwater
Deforestation-trees intercept rainwater on their leaves, take up some water from the ground and store it. By cutting down the trees, the volume of water which reaches the channel increases.