Water And Carbon Cycles Flashcards
What is an open system?
One which can exchange energy and matter with its surroundings, inputs and outputs eg. The coastal system
What is a closed system?
One which cannot exchange matter with its surroundings, but can exchange energy eg the water cycle
What is feedback?
When inputs or outputs suddenly change and stores are forced to change to restore equilibrium
What is the role of oceans as a store and source of carbon dioxide?
-Oceans play a key role in carbon cycle
-Photosynthesis by plankton generates organic compounds of carbon dioxide
-Some of this material passes through the food chain and sinks to the ocean floor where it is decomposed into sediments, destroyed at subduction zones, where ocean crusts are subducted beneath the continental plates.
-Carbon dioxide is later released during volcanic activity
-The transfer of carbon dioxide from ocean to atmosphere involves a very long time scale
What is meant by dynamic equilibrium?
Where a system tries to reach a continuous balance
What is meant by positive feedback?
Feedback that tends to magnify a process or increase its output
Water on or close to the earths surface is called?
The hydrosphere
What % earths water is oceanic?
97%
The area of land drained by a river and its tributaries is called?
Drainage basin
What are the flows occurring in the drainage basin system?
-Groundwater flow
-Throughflow
-Overland flow
-Base flow
-Infiltration
-Percolation
-Throughfall
What is water balance within a drainage basin system?
-Water balance budget refers to the balance between inputs and outputs of water in the drainage basin system
-Water balance graph show that the system is in a state of dynamic equilibrium over the year
-Changes in inputs and outputs effect soil moisture and river discharge
The role of oceans as a carbon store/sink?
-Oceans are the largest CO2 sink on earth, more than 25% CO2 that humans release into the air is absorbed into the sea
Why is the local drainage basin an open system?
A drainage basin is an example of an open system because it is open to inputs from the outside such as precipitation and is responsible for outputs out of the system of water into the sea and evaporation of water into the atmosphere.
What is river discharge
The amount of water in a rover flowing past a particular point (cumecs)
What is the river regime
Graph showing changes in river discharge over the course of a year in response to climatic changes with the seasons eg. Precipitation, temperature, evapotranspiration
Is the hydrological cycle an open or closed system?
The global hydrological cycle is a closed system (local drainage basin=open), meaning that all the water within the cycle remains as such in one form or another- not created or destroyed.
What is dynamic equilibrium
A state or act of balance between continuing processes eg. Inputs and outputs in a system. This means that when one changes, another is simultaneously altered within a system.
Example of negative feedback loop
Increasing levels of cloud cover preventing increasing solar radiation on temperatures.
What is the lithosphere
Earths upper mantle and crust- the rigid outer part closest to the surface.
What is the biosphere?
Anything biotic which is in our world
What is the hydrosphere
Stores within bodies of water- primarily the worlds oceans
What is the cryosphere
Within ice, such as areas near the poles such as ice caps or sheets or glaciers
What is the rising limb?
Indicates the amount of discharge and the speed at which it is increasing
Very steep in response to a flash flood or in small drainage basins where the response is rapid
What is the discharge on flood hydrograph?
The volume of water flowing through rivers (cumecs) Higher in larger basins
Steep catchments have lower infiltration rates
Flat catchments have high infiltration rates so more throughflow and lower peaks
What is the lag time on flood hydrographs?
Time interval between peak rainfall and discharge. Influenced by basin shape, steepness and stream order
Characteristics of a flashy hydrograph?
Shorter lag time, steeper rising limb, higher peak discharge
Physical factors affecting flood risk
-precipitation type and intensity
-temperature and evapotranspiration
-antecedent moisture
-drainage basin size and shape
-drainage density
-porosity and impermeability of rocks and soils
-slopes
-vegetation type
-land use
How does urbanisation increase the magnitude and frequency of floods?
-creation of highly impermeable surfaces such as roads, roofs and pavements
-removal of trees means less interception
-agriculture can damage the soils, removing the top layer, make soil smears and reduce percolation and make them impermeable
Bankfull
The maximum discharge a river channel is capable of carrying without flooding
Carbon sink
A store of carbon that absorbs more carbon than it releases
Example of positive feedback in the water cycle
Rising sea levels means ice shelves become unstable as they are in more contact with warmer ocean water. This leads to increased calving (breaking up of ice shelves). This leads to an increase in melting, causing sea levels to rise further.
Example of positive feedback in the carbon cycle
Increased temperatures leads to an increase in evaporation from the oceans. This leads to more cloud cover. Clouds reflect radiation from the sun, resulting in a slight cooling of temperatures.
Example of negative feedback in the carbon cycle
Increased atmospheric CO2 leads to increased temperatures, promoting plant growth and rates of photosynthesis. This in turn removes more CO2 from the atmosphere, counteracting the rise in temperatures.
Distribution of freshwater stores
-97% in oceans (salt water), 3% earths water is freshwater, almost all of which is stored as snow and ice (70%) and groundwater (29%)
-Surface and other freshwater is only 1% of all freshwater
-Most freshwater sources can be found in the northern hemisphere, where there is greater land cover, and the mild climate means not all freshwater is locked up as snow or ice and evaporation remains low
