The Drainage Basin System Flashcards
What is the drainage basin?
The catchment area from which a river system gets its water. It’s an open system, with inputs and outputs of energy and stores and transfers of water
What is a watershed
Separates one drainage basin out from another. Generally follows a ridge of high land and any rain that falls within the watershed will flow into the drainage basin
What cycle is the drainage basin part of
The hydrological cycle
What is the hydrological cycle
Starts when precipitation first lands on the surface and finishes when water leaves the basin either by evapotranspiration or as the river enters the sea through runoff
Precipitation in drainage basin
Input- water enters through land and ocean precipitation
Evapotranspiration is drainage basin
Output- Total output of water from basin directly to atmosphere
Runoff in drainage basin
Output- all water that enters a river channel and eventually flows out of the drainage basin
5 Stores in the drainage basin
Interception- by vegetation
Surface water- puddles
Soil water- occupies pore spaces between soil particles
Groundwater- water in ground beneath rocks
Channel storage- water in river
4 flows/transfers in drainage basin
Stemflow- water making its way from the leaves of the trees to the ground
Infiltration- water sinks into the soil
Overland flow- if water is unable to infiltrate it may run off the surface as overland flow
Channel flow- flows lead water to nearest river
What is the water balance
In a drainage basin shows the balance between the inputs and outputs together with changes in ground storage
What is the water balance equation
Precipitation (P) = Runoff (Q) + Evapotranspiration (E) (+/- change in storage)
What is an interception store
The precipitation that falls on the vegetation surfaces (canopy) or human made cover and is temporarily stored on these surfaces.
What is stemflow
The portion of precipitation intercepted by the canopy that reaches the ground by flowing down stems, stalks or tree bole
What is throughfall
The portion of the precipitation that reaches the ground directly through gaps in the vegetation canopy and drips from leaves, twigs and stems.
When does throughfall occur
When the canopy-surface rainwater storage exceeds its storage capacity
