drainage basins

Question 1

what are drainage basins

Answer 1

they are a local and open hydrological cycle:
1. a rivers drainage basin is the area surrounding the river where the rain falling on the land flows into that river. this area is also known as the rivers catchment.

2. the boundary of a drainage basin is the watershed. any precipitation falling beyond the watershed enters a different drainage basin.
3. drainage basins are open systems with inputs and outputs.
4. water comes into the system as precipitation leaves via evaportation, transpiration, and river discharge.

Question 2

what are the inputs of a drainage basin

Answer 2

precipitation includes all the ways moisture comes out of the atmosphere. precipitation is mainly rain, but also includes other types like snow, hail, dew and frost

Question 3

what are the stores of a drainage basin

Answer 3

1. interception - when some precipitation lands of vegetation or other structures, like buildings and concrete or tarmac surfaces, before it reaches the soil. the interception creates a significant store of water in wooded areas. interception storage is only temporary because the collected water may evaporate quickly or fall through leaves as throughfall
2. vegetation storage- water that have been taken up by plants, its all the water contained in plants at any one time
3. surface storage- water in puddles (depression storage), ponds and lakes
4. soil storage- moisture in soil
5. groundwater storage- water stored in the ground, either in the soil or in the rocks. the water table is the top surface of the zone of saturation, which is 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
6. channel storage- the water held in a river or stream channel

Question 4

what are flows in the drainage basin

Answer 4

1. infiltration- water soaking into the soil, the rate of infiltration is influenced by soil type, soil structure and how much water is already in the soil.
2. overland flow- this is also known as runoff. where water flows over the land, it can flow over the whole surface or just in channels, it occurs because rain is falling on the ground faster than infiltration can occur.
3. throughfall- water dripping from one leaf to another
4. stemflow- water running down a plant stem or a tree trunk
5. throughflow- water moving slowly downhill through the soil, it occurs faster through ‘pipes’ which are likes cracks in soil
6. groundwater flow- water flowing slowly between the water table through permeable rock, with rocks that are highly permeable with lots of joints there can be a faster groundwater flow
7. baseflow- groundwater flow that feeds into rivers through river banks and river beds
8. interflow- water flowing downhill through permeable rock above the water table
9. channel flow- water flowing in the river or stream itself, called the river discharge

Question 5

what are outputs to the drainage basin

Answer 5

1. evaporation- water turning into water vapour
2. transpiration- evaporation within leaves, plants and trees take up water through roots and transport it to their leaves where it evaporates into the atmosphere
3. evapotranspiration- process of evaporation and transpiration together
4. river discharge

Question 6

what is water balance

Answer 6

it shows the balance between inputs and outputs. the water balance affects how much water is stored in the basin. the general water balance in the UK has seasonal patterns:
1. in wet seasons, precipitation exceeds evapotranspiration, this creates a water surplus. the ground stores fill with water so theres more surface runoff and higher discharge so river levels rise.

2. in drier seasons, precipitation is lower than evapotranspiration. ground stores are depleted as some water is used and some flows into the river channel, but isnt replaced by precipitation
3. by the end of a dry season there is a deficit of water in the ground, the ground stores are recharged in the next wet season