Water and Carbon Cycle
,Location: Southwest England.. The Exmoor Factors affecting floods/river discharge
- River Exe flows through Exmouth and Tiverton and it is 35 miles
Catchment Wimbleball Reservoir regulates river flow and stores water in
long periods of high rainfall, reducing the risk of flooding and
River regime: controlling the river discharge.
- Typical seasonal patterns. More rainfall in winter – more flow/river Elevation: How far above sea level
discharge than in summer.
- Maximum elevation of 516m
- Large variation in river flow, lots of high and low points.
- Average elevation 171m. (50% of area is above 171m above
- Rapid fluctuations of river flow. – Flashy river regime.
sea level.
- High drainage density – lots of tributaries flowing into the
- As upland areas receive more rainfall (relief) the high elevation
area.
and steep slopes promote precipitation, especially in the Middle
and Upper course.
Human factors affecting flooding and runoff:
- Promotion of runoff/overland flow as water can’t infiltrate the
- The Exmoor catchment contains lots of bogs and peat. Plants
soil due to gravity/steep slope pulling it down.
such as Stagnam moss which holds up to 20 times their
weight in water.
- They perform a huge role in the drainage basin by slowing down
Hydrogeology: Permeability of rocks MOST
the transfer of water. As the water is a long-term store in the bog, it IMPORTANT
is forced underground where it percolates the rock and - Geology and permeability of runoff/river regime rocks in this
groundwater flow occurs it can take years for the water to reach catchment. 65% of water balance is runoff
the rivers. - 93.5% low/moderate permeable rocks. Only 2.5% is permeable.
- However, farmers using this land for cattle and sheep - This leads to less percolation (less long-term storage in rocks so
farming dig ditches, which create channels for the water to water gets to the river faster increasing discharge.)
travel along the surface and flow very fast down directly into the - As rocks aren’t permeable, the soil saturates very fast. When
river. it’s fully saturated water can't be absorbed so it’s runoff.
- This causes large unnatural variations in river discharge
especially after rainfall. Causing a flashy river regime and a Annual rainfall:
high risk of floods. - Upper catchment – 2,300mm rainfall (relief rain)
- This also causes the bogs to dry up and die, removing their - Average in catchment 1,300mm (can change every year)
function. Land usage/cover:
- Only 13% woodland. (less evapotrans. Less interception –
Exmoor mires project: 2000-hectare restoration more runoff)
- A £2 Million project to restore the bogs. This is done by blocking
, When has the River Exe Flooded? What are the predicted impacts of climate change
December 2012: Heavy rainfall led to the River on the Water and Carbon Cycle/Stores in the River
Exe bursting its banks, causing widespread flooding Exe?
in areas like Exeter. This was because November Water Cycle: UNCERTAINTY
was the wettest recorded. Increased Flooding: Climate change is expected to intensify
the water cycle, leading to more frequent and severe flooding
What were the Human and Physical events.in 2100 over 11,000 houses are at threat of flooding
causes? due to sea level rise.
Physical Causes Droughts: Altered precipitation patterns result in prolonged
Heavy Rainfall: Both events were characterized by dry spells, affecting water availability. Heavier less frequent
prolonged and intense precipitation, leading to rapid rain.
river swelling. November 2021 was the wettest ever
recorded. Carbon Cycle:
Soil Saturation: Prior wet conditions reduced the Wetlands and Peatlands: Drought conditions can dry out
soil's capacity to absorb additional rainfall, peatlands, leading to the release of stored carbon into the
increasing surface runoff. atmosphere.
Topography: The steep valleys in the River Exe Vegetation Changes: Shifts in climate can alter vegetation
catchment area facilitate quick runoff into the river. types, influencing carbon sequestration rates in the region.
Human Causes Explain the links between the Water and Carbon
Urbanisation: Expansion of impermeable surfaces Cycle in the River Exe Drainage Basin
in urban areas like Exeter reduces natural Soil Moisture and Carbon Storage: Adequate soil moisture
infiltration, enhancing runoff. supports plant growth, enhancing carbon sequestration.
Land Use Changes: Agricultural practices and Conversely, droughts can reduce vegetation cover, decreasing
deforestation can diminish the land's ability to carbon uptake.
retain water, contributing to faster runoff. Peatlands: In the River Exe basin, peatlands act as significant
Impacts: Over 327 properties across Devon carbon reservoirs. Flooding can lead to erosion and carbon loss,
,Location: Southwest England.. The Exmoor Factors affecting floods/river discharge
- River Exe flows through Exmouth and Tiverton and it is 35 miles
Catchment Wimbleball Reservoir regulates river flow and stores water in
long periods of high rainfall, reducing the risk of flooding and
River regime: controlling the river discharge.
- Typical seasonal patterns. More rainfall in winter – more flow/river Elevation: How far above sea level
discharge than in summer.
- Maximum elevation of 516m
- Large variation in river flow, lots of high and low points.
- Average elevation 171m. (50% of area is above 171m above
- Rapid fluctuations of river flow. – Flashy river regime.
sea level.
- High drainage density – lots of tributaries flowing into the
- As upland areas receive more rainfall (relief) the high elevation
area.
and steep slopes promote precipitation, especially in the Middle
and Upper course.
Human factors affecting flooding and runoff:
- Promotion of runoff/overland flow as water can’t infiltrate the
- The Exmoor catchment contains lots of bogs and peat. Plants
soil due to gravity/steep slope pulling it down.
such as Stagnam moss which holds up to 20 times their
weight in water.
- They perform a huge role in the drainage basin by slowing down
Hydrogeology: Permeability of rocks MOST
the transfer of water. As the water is a long-term store in the bog, it IMPORTANT
is forced underground where it percolates the rock and - Geology and permeability of runoff/river regime rocks in this
groundwater flow occurs it can take years for the water to reach catchment. 65% of water balance is runoff
the rivers. - 93.5% low/moderate permeable rocks. Only 2.5% is permeable.
- However, farmers using this land for cattle and sheep - This leads to less percolation (less long-term storage in rocks so
farming dig ditches, which create channels for the water to water gets to the river faster increasing discharge.)
travel along the surface and flow very fast down directly into the - As rocks aren’t permeable, the soil saturates very fast. When
river. it’s fully saturated water can't be absorbed so it’s runoff.
- This causes large unnatural variations in river discharge
especially after rainfall. Causing a flashy river regime and a Annual rainfall:
high risk of floods. - Upper catchment – 2,300mm rainfall (relief rain)
- This also causes the bogs to dry up and die, removing their - Average in catchment 1,300mm (can change every year)
function. Land usage/cover:
- Only 13% woodland. (less evapotrans. Less interception –
Exmoor mires project: 2000-hectare restoration more runoff)
- A £2 Million project to restore the bogs. This is done by blocking
, When has the River Exe Flooded? What are the predicted impacts of climate change
December 2012: Heavy rainfall led to the River on the Water and Carbon Cycle/Stores in the River
Exe bursting its banks, causing widespread flooding Exe?
in areas like Exeter. This was because November Water Cycle: UNCERTAINTY
was the wettest recorded. Increased Flooding: Climate change is expected to intensify
the water cycle, leading to more frequent and severe flooding
What were the Human and Physical events.in 2100 over 11,000 houses are at threat of flooding
causes? due to sea level rise.
Physical Causes Droughts: Altered precipitation patterns result in prolonged
Heavy Rainfall: Both events were characterized by dry spells, affecting water availability. Heavier less frequent
prolonged and intense precipitation, leading to rapid rain.
river swelling. November 2021 was the wettest ever
recorded. Carbon Cycle:
Soil Saturation: Prior wet conditions reduced the Wetlands and Peatlands: Drought conditions can dry out
soil's capacity to absorb additional rainfall, peatlands, leading to the release of stored carbon into the
increasing surface runoff. atmosphere.
Topography: The steep valleys in the River Exe Vegetation Changes: Shifts in climate can alter vegetation
catchment area facilitate quick runoff into the river. types, influencing carbon sequestration rates in the region.
Human Causes Explain the links between the Water and Carbon
Urbanisation: Expansion of impermeable surfaces Cycle in the River Exe Drainage Basin
in urban areas like Exeter reduces natural Soil Moisture and Carbon Storage: Adequate soil moisture
infiltration, enhancing runoff. supports plant growth, enhancing carbon sequestration.
Land Use Changes: Agricultural practices and Conversely, droughts can reduce vegetation cover, decreasing
deforestation can diminish the land's ability to carbon uptake.
retain water, contributing to faster runoff. Peatlands: In the River Exe basin, peatlands act as significant
Impacts: Over 327 properties across Devon carbon reservoirs. Flooding can lead to erosion and carbon loss,
