Temporal Variations In River Discharge

Question 1

What are river hydrographs?

Answer 1

Line graphs that plot changes in a river’s discharge over time
Shows how ‘flashy’ a river catchment is

Question 2

What is the purpose of hydrographs?

Answer 2

Warning the public whose properties are at risk

Enable flood warnings to be issued early, reducing flood risk

Question 3

What are ‘flashy’ hydrographs?

Answer 3

Short lag time, showing that the river has rise quickly due to heavy rainfall
Lag time may be longer, resulting in ‘subdued’ hydrographs

Question 4

What are the physical factors that affect storm hydrographs?

Answer 4

Large drainage basins catch more water so have higher peak discharge
Circular drainage basins have shorter lag times and higher peak discharge
If basin is already saturated surface runoff increases
Vegetation intercepts precipitation and slows water, increasing lag time

Question 5

What are the human factors that affect storm hydrographs?

Answer 5

Drainage systems created by humans have short lag time and high peak discharge as water cannot infiltrate soil
Urbanised areas lead to increase in use of impermeable building materials, surface runoff increases, leading to short lag time and higher peak discharge

Question 6

Name five climatic conditions that influence storm hydrographs

Answer 6

Precipitation type
Precipitation duration and intensity
Precipitation amount
Temperature
Evaporation

Question 7

Name five river catchment characteristics that influence storm hydrographs

Answer 7

Size of drainage basin
Porosity and permeability of soils
Slope gradient
Land use
Rock type