water cycle and carbon cycle

• Positive feedback amplifies the impacts of the original event
• Precipitation includes rain, snow, and hail
• Types of Rainfall

  • Convectional
  • Relief
  • Frontal
• Open systems receive inputs and transfer outputs of energy or matter with other systems
• Each system contains flows/transfers, inputs, outputs, and stores/components
• Streamflow includes all water that enters a drainage basin and leaves through the atmosphere or streams
• On a local scale, the carbon and water cycles are both open systems, but on a global scale, they are closed systems
• Infiltration

  The process of water moving from above ground into the soil. The infiltration capacity refers to how quickly infiltration occurs. Grass crops and tree roots create passages for water to flow through from the surface into the soil, increasing the infiltration capacity. If precipitation falls at a greater rate than the infiltration capacity, overland flow will occur
• Dynamic equilibrium in a system is when inputs equal outputs despite changing conditions
• Components of Systems

  • Inputs
  • Outputs
  • Stores
  • Flows
  • Boundaries
• Water Cycle at Local Scale

  Water may be lost as an output through evapotranspiration and runoff, but more water may be gained as an input through precipitation. As the inputs and outputs are not balanced, it is an open system
• Closed systems are when energy inputs equal outputs
• Negative feedback nullifies the impacts of the original event, leading to dynamic equilibrium
• Evapotranspiration is compromised of evaporation and transpiration
• If precipitation falls at a greater rate than the infiltration capacity

  Overland flow will occur - Moderate/Fast
• Throughflow

  Water moves through the soil and into streams or rivers
• Groundwater Flow

  Water moves through the rocks
• Sandy soils drain quickly because they have

  Lower field capacity, larger pore spaces, and natural channels from animals such as worms
• The water table is used by researchers to assess drought conditions, health of wetland systems, success of forest restoration programmes, etc.
• Stemflow


  Flow of water intercepted by plants or trees, down a stem, leaf, branch, or other part of a plant - Fast
• The water balance of an area changes dependent on physical factors, especially during seasonal variations of temperature and precipitation
• Percolation rate is dependent on

  Fractures that may be present in the rock and the permeability of the rock - Slow
• Surface Runoff (Overland flow)


  Water flows above the ground as sheetflow or in rills - Fast
• Water table


  The upper level at which the pore spaces and fractures in the ground become saturated
• Tree roots create passages for water to flow through from the surface into the soil

  Increases the infiltration capacity
• Clay soils have

  High field capacity and smaller pore spaces, resulting in a slower flow rate
• Streamflow


  Water that moves through established channels - Fast
• The water balance is important to explain droughts or floods
• Some sports fields have sandy soils


  To reduce the chance of waterlogged pitches, but this may also increase the flood risk elsewhere - Moderate/Fast
• Speed of flow in Throughflow is dependent on

  Type of soil
• Percolation


  Water moves from the ground or soil into porous rock or rock fractures
• Groundwater flow is usually slow but variable in


  Jointed rocks such as limestone in Karst environments
• The water balance uses the formula: Precipitation = Total Runoff + Evapotranspiration +/- (change in) Storage
• Interception


  Water intercepted by plants on their branches and leaves before reaching the ground - Short-term
• Changes to the water cycle are impacted on a local scale by deforestation and storm events
• Factors impacting le on a local scale

  • Deforestation - There is less interception by trees so surface runoff increases. The soil is no longer held together by roots, so soil water storage decreases. There are fewer plants so transpiration decreases
  • Storm Events - Large amounts of rainfall quickly saturate the ground to its field capacity. No more water can infiltrate the soil, increasing the surface runoff. Storm events are therefore less effective at recharging water stores than prolonged rainfall
  • In 24 hours if 20mm of rain fell evenly this would infiltrate the soil and percolate into the groundwater stores as well, with low surface runoff. In 1 hour if 20mm of rain fell, there would be less water infiltrating the soil and percolating into the rocks, reducing the replenishment of groundwater stores, but increasing runoff
  • Seasonal Changes: Spring - More vegetation growth so more interception by vegetation. Summer - Likely to be less rain in summer. Ground may be harder and therefore more impermeable encouraging surface runoff. Autumn - Less vegetation growth so less interception. Seasonally more rainfall. Winter - Frozen ground may be impermeable and encourage runoff. Snow discourages runoff and takes time to melt, slowing down the processes that occur within the water cycle
• The water budget is dependent on type, depth and permeability of the soil and bedrock
• The soil water budget shows the annual balance between inputs and outputs in the water cycle and their impact on soil water storage/availability
• Seasonal Variation of the Soil Water Budget: Autumn - In Autumn, there is a greater input from precipitation than there is an output from evapotranspiration as deciduous trees lose their leaves
• The water budget is never the same due to varying conditions year on year and the process is affected by how much rainfall/dry weather there is the previous year