Water and Carbon Flashcards
Explain the concept of dynamic equilibrium in the water cycle (4)
- when the inputs and outputs in a system are balanced and the stores stay the same.
- Rivers are constantly changing over time to reach a balance with the processes that determine their form. As the flows of energy and materials passing through the river change over time, so to does the river towards this equilibrium
Explain the concept of Negative feedback in the water cycle (4)
- when a system acts by lessening the effect of the original change and ultimately reversing it.
- as the surface temperature of the Earth increases there are increased levels of evaporation from the oceans. This increased evaporation results in more clouds forming in the lower atmosphere
- These clouds refect some solar radiation back into space, slightly decreasing the surface temperature
Outline the amount of water stored in the Earth’s different spheres (4)
96.5% - Hydrosphere
1.7% - Cryosphere
1.7% - Lithosphere
0.001% - Atmosphere
Outline the share water in fresh water stores (4)
- 3% of all water is fresh water
- 79% of fresh water stored in ice caps and glaciers
- 20% of fresh water stored as ground water
- 1% of fresh water is easily accessible surface water
Explain the role of condensation in the water cycle (4)
- It is the process by which water vapour changes to liquid water
- It is a flow from the atmosphere to the hydrosphere
- Condensation takes place when the temperature of air is reduced to dew point but is volume remains constant.
- It also occurs when the volume of air increases but there is no addition of heat (adiabatic cooling). This happens when air rises and expands in the lower pressure of the upper atmospehre.
Explain factors driving Cryospheric change (4)
- They are the processes that affect the total mass of ice at any scale.
- Glacial periods mean there is far more water stored glaciers, and sea levels were 120m lower than present
- Permafrost is formed when air temperatures are so low that they freeze any soil and groundwater present
- Global warming is seeing the melting of polar ice caps
Outline the concept of a drainage basin (4)
- An area of land drained by a river and its tributaries. It includes water found on the surface, in the soil and in near-surface geology
- It is an open system as water is inputted as precipitation and outputted through channel flow and evapotranspiration
- Some water is stored in interception, surface and channel storage, soil and groundwater stores
- Drainage basins are separated from each other by highland called a water shed
Outline the process of Evaporation in the water cycle (4)
- The processes by which liquid water changes to a gas. This requires energy, which is provided by the sun and is aided by wind.
- Results in the increase in storage in the atmosphere and a loss of water from the hydrosphere and biosphere
- Increasing due to climate change and global warming
Outline the role of evapotranspiration in the water cycle (4)
- The total output of water from the drainage basin directly back into the atmosphere
- Transpiration is the loss of water from vegetation through pores on their surfaces
- Evaporation will be from surface storage like puddles
- This counts as an ouput from the open system
Outline the role of Groundwater flow in the water cycle (4)
- the slow movement of water through underlying rocks
- is the slowest flow in the drainage basin
- movement of water from groundwater storage to channel flow
Outline the role of infiltration in the water cycle (4)
- The downward movement of water from the surface into soil
- The rate of this movement is known as the infiltration rate
- Soil porosity if the most important determing infiltration rate
- Infiltration rate declines rapidly during the early part of a rainstorm event
Explain the role of Interception in the water cycle (4)
- the precipitation that falls on the vegetation surfaces or human-made cover and is temporarily stored on these surfaces.
- Acts a store between flows
- The size of the store can be decreased due to evaporation
- The density of vegetation cover determines the amount of interception storage
Explain the role of overland flow in the water cycle (4)
- The tendency of water to flow horizontally across land when rainfall has exceeded the infiltration capacity of the soil and all surface stores are full to overflowing.
- It can flow as sheetflow (large difuse flow of water) or rills (small channels)
- The rate of overland flow is determined by the impermeability of the soil
Outline the role of percolation in the water cycle (4)
- The downward movement of water within the rock under the soil surface.
- Rates vary depending on the nature of the rock
- It is the flow between the stores of soil and groundwater storage
Outline the role of stemflow (4)
- The portion of precipitation intercepted by canopy that reaches the ground by flowing down stems, stalks or tree boles
- It is the flow connecting the stores of interception and soil storage
- In very heavy storms it can flow straight down the trunks of trees.
Outline the role of throughfall in the water cycle (4)
- precipitation that reaches the ground directly through gaps in the vegetation canopy and drips through gaps in the vegetation canopy
- it connects the stores of interception to another until it eventually hits the ground
- it is dependent on the amount of vegetation, where there is no vegetation it is simply precipitation
Explain the role of throughflow in the water cycle (4)
- the movement of water down slope through the subsoil under the influence of gravity
- it eventually reaches the nearest channel
- The more vegetated an area, the faster the rate of throughflow becuase it is aided by root channels in the soil
Explain the role of transpiration (4)
- the loss of water from vegetation
- it is difficult to separate evaporation from transpiration so the total amount outputted from the drinage basin is refferred to as evapotranspiration.
- transpiration depends on the amount of vegetation, humidity, temperature, wind and light.
Assess factors leading to a soil moisture deficit (6)
- Temperature. If temperature is warmer, evapotranspiration will increase, meaning more water leaves the soil, leading to the deficit. VS temperature is not as important in some parts of the world where temperatures vary little
- Precipitation. Precipitation is the input into the system. With low precipitation then the deficit will occur.
Outline features of the flood hydrograph (4)
- Peak rainfall - the maximum amount of rainfall
- Peak discharge - the maximum amount of water held in the channel
- Lag time the time taken between peak rainfall and peak discharge
- Rising limb the increase in discharge to peak discharge
- Falling limb shows the return of discharge to normal/base flow on a hydrograph
Explain the characteristics of a flashy flood hydrograph (4)
- Short lag time as there has been a short amount of time between peak rainfall and peak discharge
- High peak discharge the river has liekly gone over its its bankfull due to a significant amount of throughflow
- Steep rising limb as there has been a significant amount of throughflow quickly
Explain how drainage basin shape impacts the flood hydrograph (4)
- Drainage basins that are more circular in shape lead to more flashy hydrographs than those with are long and thin
- This means that there is a steeper rising limb
- This is because each point in the drainage basin is roughly equidistant from the measuring point on a river
Explain how steep sided basins affect the flood hydrograph (4)
- Steep sided basins tend to have flashier hydrographs than gently sloped river basins
- This is becuase water flows more quickly on the steep slopes, whether as throughflow or overland flow, so gets to the river more quickly
- This will lead to a steeper rising limb
Explain how drainage density affects the flood hydrograph (4)
- High drainage density means the basin has a lot of surfacr streams acting as tributaries to the main river
- If there is high drainage density thenthere will be a flashy hydrograph
- All water will arrive at the measuring station at the same time
- This will increase the rising limb and the peak discharge
Explain how saturated soil impacts the flood hydrograph (4)
- If the drainage basin is already saturated by antecedent rainfall then overland flow increases because infiltration capacity has been reaches
- Since overland flow is the fastest of the transfers the lag time is reduced.
- Peak discharge will be higher meaning the hydrograph will be flashy