Drainage basin and definitions (+ water balance etc)


A Levels Geography (Rivers) Flashcards on Drainage basin and definitions (+ water balance etc), created by Alice Kimpton on 14/12/2015.
Alice Kimpton
Flashcards by Alice Kimpton, updated more than 1 year ago
Alice Kimpton
Created by Alice Kimpton about 8 years ago

Resource summary

Question Answer
What is a drainage basin? area surrounding the river where precipitation falling on the land flows into that river. Also called the river's catchment.
What is watershed? boundary of a drainage basin; any precipitation falling beyond the watershed enters a different drainage basin.
What is an open system? Drainage basin with inputs and outputs.
What is a closed system? A cycle with no inputs or outputs. Example: the Earth, nothing coming in or out.
Definition of...Inputs All the ways moisture comes into the atmosphere. Mainly rain, snow hail, dew and frost.
Ways in which precipitation can be stored? (5 types- 1) > Interception is when some precipitation lands on vegetation or other structures, like buildings and concrete, before it reaches soil. Interception creates significant store of water in wooded areas. This type of storage is only temporary because collected water evaporated quickly.
Ways in which precipitation can be stored? (5 types- 2) > Vegetation storage is water that's been absorbed by plants. It's contained in plants at any one time.
Ways in which precipitation can be stored? (5 types- 3) > Surface storage including water in puddles(depression storage), ponds and lakes
Ways in which precipitation can be stored? (5 types- 4) > Ground water storage is water stored in the ground., either in soil or in rocks. The water table is the top surface of the zone of saturation- the zone of soil or rock where all the pores in the soil or rock are full of water. Porous rocks that hold water are called aquifers.
Ways in which precipitation can be stored? (5 types- 5) > Channel storage is water held in a river or stream channel.
Flows and processes- there are 10! > surface runoff > throughfall > stemflow > throughflow > infiltration > percolation > ground water flow > baseflow > interflow >channel flow
Describe surface runoff (overland flow)? ...water flowing over the land. It can flow over the whole surface or in little channels. Surface runoff is common in areas with torrential rain falls on hard baked land
Describe through fall flow? ...water dripping from one leaf to another
Describe stem flow ? ...water running down a plants stem or tree trunk
Describe throughflow? ...water moving slowly downhill through the soil. It's faster through 'pipes'- things such as cracks in the soil, or animal burrows
Describe infiltation? ...water soaking into the soil. Infiltration rates are influenced by soil types, structure and how much water's already in the soil. In heavy storm water can't infiltrate fast enough, so flows over the surface
Describe percolation? ...water seeping down through soil into water table
Describe groundwater flow? ...water flowing slowly below the watertable through permeable rock. Water flows slowly through most rocks, but rocks that are highly permeable with lots of joints can have faster groundwater flows, e.g. limestone
Describe baseflow? ...groundwater flow that feeds into rivers through river banks and river beds
Describe interflow? ...water flowing downhill through permeable rock above the water table
Describe channel flow? ...water flowing in the river or stream itself. This is also called the river's discharge
Outputs- there are 4! > evaporation > transpiration > evapotranspiration > river discharge/ river flow
Describe evaporation? ...water turning into water vapour- liquid to a gas
Describe transpiration? ...evaporation from plant leaves- plants and trees take up water through their roots and transport it to their leaves where it evaporates into the atmosphere
Describe evapotranspiration? ...the process of evaporation and transpiration together
River discharge/ river flow... is just another output
What is water balance? ...shows balance between inputs and outputs for a given month. Stored in the basin.
In a water balance graph what is the main input and output? Main input is precipitation Main output is channel discharge and evapotranspiration
Describe surplus in the water balance? occurs in wet seasons as precipitation exceeds evapotranspiration. The grounds stores fill with water so there's more surface runoff and higher discharge, so river levels rise.
Describe deficit in the water balance? occurs in drier months, as precipitation is lower than evapotranspiration. Ground stores are depleted as some water is used by plants & humans, some flows into river channel, but then not replaced by more precipitation.
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