Water Positive And Negative Feedback

Question 1

Example of Positive Feedback, in relation to storm events

Answer 1

1. Precipitation increases due to more storm events (winter in UK)
2. Increased overland flow, throughflow groundwater flow
3. Amount of water in river store in a drainage basin increases
4. Potentially more evaporation, so more clouds, so more precipitation so accelerates initial change

(Implications for life on Earth

• More water in rivers and groundwater, so continuous supply of water for life from aquifers and rivers
• Flooding

Implications (effects) for climate
- More clouds, so wetter)

Question 2

Example of Positive Feedback, in relation to less precipitation

Answer 2

1. Precipitation decreases - summer in UK
2. Less overland flow, throughflow groundwater flow, if rains more interception as leaves on trees
3. More transpiration, evaporation
4. Amount of water in river store in a drainage basin decreases
5. Potentially less evaporation, so less clouds, so less precipitation so accelerates initial change

(Implications for life on Earth

• Less water in rivers and groundwater, so could create drought, so less water for drinking in aquifers
• Arable crops – less rainfall, so crop failure and food supply issues. May have to grow more drought resistant varieties – UK turning to Spain!!!!

Implications for climate
- Less clouds, so drier, seasonal climate change)

Question 3

Example of Positive Feedback, in relation to impermeable surfaces

Answer 3

1. More water in urban rivers due to impermeable surfaces
2. Precipitation - more overland flow, greater water flow through drains, sewers, less natural infiltration, throughflow, percolation, groundwater flow
3. Potentially more evapotranspiration, so more clouds, so more precipitation
4. Amount of water in river store in a drainage basin increases
5. More precipitation falling to ground so accelerates initial change

(Implications for life on Earth
More water in rivers , so continuous supply of water for life for water supply
Flooding

Implications for climate
More clouds, so wetter)

Question 4

Example of Positive Feedback, in relation to ice melting

Answer 4

1. More ice melting in oceans
2. More ocean exposed, therefore absorbs radiation from sun
3. Heat of ocean melts more ice – sea ice and glaciers entering ocean. So accelerates initial change
4. Ocean heats up

( Knowledge box

1. Ice reflects radiation from sun, so less heat absorbed
2. If ice coverage is less more heat is absorbed by ocean)

(Implications for life on Earth
Sea levels rise
Flooding of low level islands, Kiribati
People forced to migrate, from Kiribati to Fuji

Implications for climate
Ocean heats up – holds less carbon?
GE and EGE increases)

Question 5

Example of Negative Feedback, in relation to River Exe

Answer 5

1. Less water in peat bogs on Exmoor due to drainage ditches dug by farmers
2. Ditches blocked by Exmoor National Park, SW water, Env Agency
3. Peat is now waterlogged so lessens effect of original change
4. Amount of water in peat bogs increases as it is trapped

(Implications for life on Earth
Peat bog restored – ecosystem supports flora and fauna
Less flooding

Implications for climate
More peat bog, so more carbon stored?
GE and EGE is lessened)

Question 6

Example of Negative Feedback in WATER AND CARBON Cycle

Answer 6

1. Phytoplankton (part of food web) populations increasing due to warmer climate
2. Clouds form due to phytoplankton processes – releases dimethylsulphide that promotes condensation and cloud formation and so more rain
3. Clouds cool Earth as block out sun
4. Less phytoplankton, so less clouds, so lessens effect of original change

(Implications for life on Earth
Less phytoplankton (food source for fish) – part of food chain

Implications for climate
Less clouds? More clouds? less rainfall over ocean, cooler?
Lessen GE and EGE)