Freshwater - Drainage basin hydrology + geomorphology Flashcards
What is the global hydrological cycle?
A closed system - the Earth’s water never changes in quanitity, but constantly changes location and form as it moves through the cycle.
What is a drainage basin?
The area of land from which a river recieves water (area of land drained by a river and its tributaries) -> its catchment area.
What is the name of the higher land that separates river basins?
the watershed (basin boundary).
What is the largest drainage basin in the world?
The Amazon Basin - 7.5 million km^2 (The size of Europe)
What is North America’s largest drainage basin?
The Mississippi Basin (spans almost 50% of the US).
Why is any drainage basin system an open system within the closed system of the global hydrological cycle?
- Water can cross the boundaries of a drainage basin
- The amount of water in a drainage basin varies over time
What are 4 important things a drainage system has?
- Inputs = additions of water
- Stores = storage of water
- Flows (transfers/processes) = movements of water
- Outputs = losses of water
Flow diagram of drainage system
What are factors that affect the store + transfer of water in a drainage basin?
- Climate - temperature
- Soil type
- Geology
- Climate- rainfall
- Relief
- Land use
Why and how does ‘Climate - temperature’ - affect the store + transfer of water in a drainage basin?
- Climate - Temperature –> >Evapotranspiration increases with temperature
>Ice - water locked in ice becomes a store not a flow. Maybe a flow later.
>Frozen ground - prevents infiltration (transfer to groundwater)
>Snow-capped peaks hold water back until thaw (delayed flow)
Why and how does ‘Soil type’ affect the store + transfer of water in a drainage basin?
- Permeability
- Clay/sand
- Impermeable soils prevent infiltration + cause surface saturation
Why and how does ‘Geology’ affect the store + transfer of water in a drainage basin?
- Permeability of the surface
- Granite/sandstone
- Impermeable rocks prevent infiltration + cause surface saturation
Why and how does ‘Climate - rainfall’ - affect the store + transfer of water in a drainage basin?
- Intensity + duration –> impact on ground saturation
Why and how does ‘Relief’ affect the store + transfer of water in a drainage basin?
- Steeper gradients reduce infiltration + increases surface runoff
Why and how does ‘Land use’ affect the store + transfer of water in a drainage basin?
- Permeability –> urban vs rural land surfaces will reduce infiltration (if impermeable)
> Man-made drainage can be used to transfer water
> Forested slopes intercept more precipitation, increased levels of evapotranspiration + reduce surface runoff
> Urban surfaces are impermeable and increase rapid surface runoff (cement), evaporation and interception
