factors affecting river discharge Flashcards
What factors influence the discharge of a river?
The weather (e.g. rainfall, temperature, and previous weather conditions), other physical factors (e.g. relief and rock type), and by human land use
How does the amount and type of rainfall affect a river’s discharge?
A lot of rain falling causes high river levels, while less rainfall results in lower river levels. High amounts of rain saturate the soil and underlying rock. In the case of drizzle, there is time for water to infiltrate the soil and underlying rock, freeing up space for more rain
How does temperature affect a river’s discharge?
This affects the loss of water from the drainage basin and therefore the level of discharge. When temperatures are higher, there is greater loss via evaporation and transpiration, so river levels go down
How do previous weather conditions affect a river’s discharge?
If it has been dry, it will take longer for the water to reach the river and the amount will be less than if there had been a number of wet days
How does relief affect a river’s discharge?
Steep slopes encourage fast run-off as the water spills rapidly downwards due to gravity
How does the rock type affect a river’s discharge?
This determines how much water infiltrates and how much stays on the surface. Areas with impermeable rocks, such as granite, have more surface rivers than permeable rocks such as chalk
What are examples of human land use that affect the discharge of a river?
Deforestation and urbanization
How does deforestation affect a river’s discharge?
If trees are removed, water reaches the surface faster and the trees do not extract water from the ground
How does urbanization affect a river’s discharge?
Expanding towns creates an impermeable surface. This is made even worse by building drains to take the water away from buildings quickly – and equally quickly into rivers
