Drainage Basins Flashcards
What are the keywords for storage and inputs in a drainage basin?
INPUTS
Precipitation- Includes all the ways moisture comes out of the atmosphere e.g snow, hail, dew and frost.
STORAGE
Interception, When water lands on vegetation or roads etc before it reaches the soil, interception creates a significant water store in wooded areas, Interception storage is largely temporary as it may evaporate or fall from leaves as throughfall.
Vegetation, all the water that is taken up by plants.
Surface storage, Includes water in puddles (depression storage), ponds and lakes.
Soil storage, all the moisture in the soil
Groundwater storage, is water stored in the ground in soil and in rocks, the water table is the top surface of the zone of saturation where all of the pores in the rocks are full of water, Porous rocks that hold water are called aquifers.
Channel storage - Water stored in the river or stream.
What are the keywords for flows and outputs in a drainage basin?
FLOWS
> Infiltration, Water soaking into the soil, infiltration rates are influenced by soil type, soil structure and how saturated the soil already is.
Overland flow, Water that flows over the land when precipitation is higher than the rate of infiltration.
Throughfall, water dripping off leaves.
Stemflow, Water running down a tree trunk or stem.
Percolation, when water seeps down into the water table.
Groundwater flow, When water flows slowly through permeable rocks, when rocks such as limestone are very permeable it can be faster.
Baseflow, groundwater that flows into rivers through river beds and banks.
Interflow, Water seeping through soils.
Channel flow - When water flows through a channel such as a river.
OUTPUTS
> Evaporation - Water turning into water vapour.
> Transpiration - Evaporation From leaves after being taken up by roots.
> Evaportranspiration - Both Evaporation and Transpiration together. (Potential evaporation is the potential for water loss and actual evapotranspiration is what actually happens e.g deserts have high potential due to high temperatures but low actual due to lack of moisture in atmosphere.
> River discharge is the flow of water out of a drainage basin.
How does the Water balance work?
The water balance is worked out by calculating inputs and outputs and working out the total effect on the stores, this could lead to water surplus, water defecit and ground water depletion and recharge.
