Water - Drainage Basins Flashcards
What is overland flow?
Water which flows horizontally across land surfaces when rainfall has exceedeed the infiltration capacity of the soil and all surface stores are full.
What is percolation?
Downward movement of water within the rock under the soil durface.
What is run-off?
All the water that enters a river channel and eventually flows out of the drainage basin.
What is stemflow?
The portion of precipitation which is intercepted by the canopy, reaching the ground by running down stems or stalks.
What is the term saturated used to describe?
Any water store which has reached its maximum capacity.
What is throughfall?
Precipitation which reaches the ground directly through gaps in the canopy and drips from leaves, twigs and stems.
When does throughfall occur?
When canopy-surface rainwater storage exceeds its capacity.
What is throughflow?
The movement of water down-slope through subsoil under the influence of gravity.
When is throughflow most effective?
When underlying permeable rock prevents further downward movement.
What is transpiration?
The loss of water from vegetation through stomata on their surfaces.
What is the water balance?
The balance between inputs and outputs in a drainage basin.
How is a drainage basin formatted through systems?
In a cascading system, a series of open systems where the output of one is the input to the next.
What is a drainage basin?
The area that supplies a river with its supply of water.
What is the input to drainage basins?
Precipitation.
What percentage of rainfall does needle-leaf trees capture?
22%.
What percentage of rainfall does broad-leaf deciduous forests capture?
19%.
What percentage of rainfall does some rainforests intercept as much as?
58%.
