Physical Crib Sheets : (Adair Verey)
Hydrology and Fluvial Geomorphology
1.1 The drainage basin system
Inputs : Precipitation
• Caused by one or more of the following processes :
• Uplift in a low pressure system (cyclonic or frontal precipitation)
• Uplift over a hill or mountain range (orographic precipitation)
• Uplift over a warm land or sea surface (=convectional precipitation)
• Air rises and expands, causing expansion cooling
• As air cools it reaches dew point temperature and condensation begins on condensation nuclei
Outputs : Evaporation, evapotranspiration and river discharge
- Evapotranspiration : Water exiting the system through either evaporation from surfaces or transpiration from
plants.
• Type of plants : More vegetation = greater evapotranspiration
- However more vegetation = ground shade and humidity store so counteracts
• Amount fo surface storage
• Season
• Humidity : PE decreases
• Sunshine : PE increases
• Wind Velocity : PE increases
• Temperature : Rate of PE increase
Note :
Evaporation = water changing from the liquid to vapour state
Transpiration = loss of vapour from plants through stomata
Potential Evapotranspiration = Maximum amount of water which could be evaporation under given conditions with
unlimited supply.
Soil Water Balance :
•Soil Moisture Loss : When ET>ppn soil begins to dry out in
summer : Rainfall is lowest and Et is highest
•Soil Moisture deficit : Occurs when there isn’t enough water to
supply the potential Evapotranspiration. Irrigation used to make
up the deficit
•Soil Moisture Recharge : In Autumn and Winter rainfall
increases, plant growth slows and temperature decreases so
ppn>ET
- River Runoff (Or ‘Runoff’) : The amount of water leaving the drainage basin system via the mouth of the river
• Size and length of the river
• Climate of the region
• Storms
• Urbanisation
• Water extraction
Hydrology and Fluvial Geomorphology
1.1 The drainage basin system
Inputs : Precipitation
• Caused by one or more of the following processes :
• Uplift in a low pressure system (cyclonic or frontal precipitation)
• Uplift over a hill or mountain range (orographic precipitation)
• Uplift over a warm land or sea surface (=convectional precipitation)
• Air rises and expands, causing expansion cooling
• As air cools it reaches dew point temperature and condensation begins on condensation nuclei
Outputs : Evaporation, evapotranspiration and river discharge
- Evapotranspiration : Water exiting the system through either evaporation from surfaces or transpiration from
plants.
• Type of plants : More vegetation = greater evapotranspiration
- However more vegetation = ground shade and humidity store so counteracts
• Amount fo surface storage
• Season
• Humidity : PE decreases
• Sunshine : PE increases
• Wind Velocity : PE increases
• Temperature : Rate of PE increase
Note :
Evaporation = water changing from the liquid to vapour state
Transpiration = loss of vapour from plants through stomata
Potential Evapotranspiration = Maximum amount of water which could be evaporation under given conditions with
unlimited supply.
Soil Water Balance :
•Soil Moisture Loss : When ET>ppn soil begins to dry out in
summer : Rainfall is lowest and Et is highest
•Soil Moisture deficit : Occurs when there isn’t enough water to
supply the potential Evapotranspiration. Irrigation used to make
up the deficit
•Soil Moisture Recharge : In Autumn and Winter rainfall
increases, plant growth slows and temperature decreases so
ppn>ET
- River Runoff (Or ‘Runoff’) : The amount of water leaving the drainage basin system via the mouth of the river
• Size and length of the river
• Climate of the region
• Storms
• Urbanisation
• Water extraction
