Water Cycle

• Hydrological cycle

  It is the circulation of water around the earth. It is a closed system so the amount of global water is finite and constant
• Why is the hydrological cycle a closed system

  No water enters or exits
• Closed system


  Input, output and transfer of energy but not matter or mass

  Eg hydrological cycle
• Open system

  Inputs and outputs of both energy and matter eg drainage basin system
• Solar energy

  A main driving factor in the hydrological cycle. Energy from the sun, heating water and causing evaporation/transpiration
• Gravitational potential energy

  Ways in which water accelerate under gravity, this transporting it to rivers and eventually to the sea
• Water budget

  The annual balance between inputs and outputs into a drainage basin
• 4 main stores of water

  Hydrosphere

  Atmosphere

  Cryopshere

  Biosphere
• Inputs into drainage basins

  Precipitation

  Channel precipitation
• Flows/fluxes/processes of a drainage basin

  Stemflow

  Through flow

  Overland flow

  Infiltration

  Through flow

  Percolation

  Groundwater flow

  Ablation
• Stores in a drainage basin

  Vegetation

  Surface water

  Rivers and lakes

  Soil moisture

  Ground water

  Channels storage
• Outputs from the drainage basin

  Evaporation

  Transpiration

  Evapotranspiration

  Sublimation

  Run off
• Evaporation

  The process by which liquid water is transformed into water vapour which is a gas
• Sublimation

  When ice sheets, glacier and snow fields transform water from a solid to a gas
• Transpiration

  The process by which water is lost from a plant through the stomata in its leaves
• Evapotranspiration

  The total amount of moisture removed by evaporation and transpiration from a vegetated land surface
• Condensation


  The process where water vapour cool to form water
• Ablation

  The melting of ice, mainly during the summer months, and usually at the snout end of the glacier
• Precipitation

  Rainfall
• Interception

  When water is prevented from reaching the surface by vegetation such as trees
• Overland flow

  When the outcome of rainfall intensity on a slope is greater than the rate at which the water can infiltrate into the soil. A thin layer of water forms on the surface and it begins to move downslope under gravity
• Throughflow

  The transfer of water from the soil storage zone to the channel at a much slower rate than overland flow
• Infiltration

  The passage of water into the soil. Takes place at a higher rate at the start of a storm but as the soil becomes saturated the rate falls
• Percolation

  The downward Vertical movement within the soil. The water then enters the groundwater store
• Groundwater

  Water that collects underground in the pore spaces in the soil and rock
• Groundwater flow

  Water in the groundwater store is transferred into through the rock and into the bed of the river
• Channel storage

  All the water which enters a river and flows out of the drainage basin
• Physical factors affecting the flows of a drainage basin

  Vegetation

  Soil

  Geology

  Climate
• Physical factors affecting the inputs of the drainage basin

  Climate

  Weather

  Relief
• Orographic rain

  When air is forced to rise over a barrier such as a mountain, it cools and condensation takes place causing rain
• How does relief affect the inputs in a drainage basin

  Areas of high relief lead to orographic rainfall. When this takes place the leeward slope receives very little rain, which is known as the shadow effect
• Convectional rainfall

  When the land becomes hot, the air above it becomes warmer, expands and rises. As it rises, the air cools and its ability to hold water vapour in it decreases. Condensation occurs and clouds develop. If the air continues to rise rain will fall
• Cylonic rainfall

  This happens when warm ait, which is lighter and less dense, is forced to rise over cold denser air. As it rises the air cools and its ability to hold water decrease. Condensation occurs and clouds and rain form
• How does climate and weather affect the drainage basin

  Can lead to different types of rainfall such as cyclonic and conventional.

  Convectional rainfall is common in tropical rainforest and the UK
• 3 types of rainfall

  Cyclonic

  Orographic

  Convectional
• How does climate affect drainage basin

  Has a role in influencing the type and amount of precipitation. Also has an impact of Vegetation type
• What impact does soil have on the drainage basin

  Determines the amount of infiltration and throughflow.

  Indirectly, affects the type of vegetation
• How does geology impact the drainage basin

  Has an impact on subsurface processes such as percolation and groundwater flow.

  Indirectly, it can alter soil formation
• Impact relief have on the drainage basin

  Can impact amount of precipitation

  Slopes can affect the amount of runoff
• How does Vegetation impact the drainage basin

  Affects the amount of interception, infiltration and occurrence of overland flow, as well as transpiration rates