river environments - factors affecting river discharge

Question 1

rock and soil type

Answer 1

• permeable rocks (such as sandy soils) absorb water easily, so surface run-off is rare
• impermeable rocks and soil (such as clay soils) are more closely packed - rainwater cannot infiltrate so more water reaches the river more quickly

Question 2

land use/vegetation cover

Answer 2

• in rural areas, rainwater reaches the river faster as channels are created due to ploughing, this increases discharge
• in urban areas, roads (concrete) are impermeable, therefore water can’t be absorbed, it runs into drains and then spills into lakes

Question 3

amount of rainfall

Answer 3

• rainfall that has previously fallen will be absorbed and the ground becomes saturated. rain that falls afterwards will not be absorbed and will just flow as the surface run -off
• heavy, continual rainfall means more water will flow into the river

Question 4

relief

Answer 4

• steep slopes mean rainwater can run down the slope faster and is less likely to infiltrate

Question 5

weather conditions

Answer 5

• hot weather increases surface run-off as the ground becomes dry and cannot absorb water