Case study of how a river is affected by processes in the water cycle Flashcards
Where is the River Exe?
Source in exmoor, mouth is exmouth
What is the maximum elevation of the river exe?
514m
What is the lowest elevation of the river exe?
26m
How much of the river is underlain by impermeable rocks?
84.4%
What type of land use dominates the area of the river exe?
Grassland
How much does grassland account for in the river exe?
67%
What is the water balance equation?
P = O + E +/- soil water storage
How much does runoff account for in the river exe’s water balance?
65%
Why does the river exe have such a high runoff rate?
Impermeable nature of bedrock reduces percolation
Drainage ditches on Exmoor reduce the amount of soil water storage
The water cycle and water balance have been significantly affected by two recent developments, which ones?
Construction of Wimbleball Reservoir
Restoration of peatland on Exmoor
What river was dammed to create Wimbleball Reservoir?
River Haddeo
What does the reservoir do?
Supply water to Exeter and parts of East Devon
Regulates water flow ensuring a steady flow regime
Prevents the peas and troughs of water discharge that make flooding or drought more likely
Why have drainage ditches been dog in the peat bogs of Exmoor?
To make it suitable for farming
What is the problem with the drainage ditches?
Increased the speed of water flow to the Exe, which reduces water quality as more slit is carried downstream
Ugly scars have been left
Peat has dried out - decomposition has occurred releasing carbon
What project has worked to restore the peat bogs?
The Exmoor Mires project
How have The Exmoor Mires project worked to restore the peat bogs?
Blocked drainage ditches with peat blocks or moorland bales
Why have the Exmoor Mires project blocked drainage ditches with peat blocks or moorland bales?
To increase water content and return the ground to the saturated boggy conditions
Why is it important the drainage ditches return to boggy conditions?
Help retain carbon stored within the peat
How many hectares does TEMP aim to restore?
2000
What will the benefits be to restoring 2000ha of Exmoor to boggy conditions?
More water storage in upper catchments Improved water quality More carbon storage Improved opportunities Improved grazing and water supply for animals
Why is water storage in upper catchments a benefit of TEMP?
Water transfer is slowed, increasing storage capacity and ensuring a steady supply of water throughout the year
Why is improved water quality a benefit of TEMP?
Slower through flow means that less sediment is carried into rivers. Water is cleaner less expensive to treat and good for wildlife
Why is more carbon storage a benefit of TEMP?
Peat is essentially carbon and water, and therefore an important carbon store. Dry peat, however releases carbon dioxide through oxidation. By encouraging the re-wetting of peat and active peat growth, CO2 is naturally absorbed from the atmosphere and stored
Why is improved opportunities a benefit of TEMP?
It will advocate opportunities for education, leisure and recreation. Peatland habitats are very biodiverse, with many species of plants, birds, butterflies and insects
Why is improved grading and water supply for animals a benefit of TEMP?
Animals benefit form having year round drinking water, as well as improved grazing during the drier parts of the year
By 2010, how much peat moorland was restored?
1000ha
How many ditches have been blocked?
100km
By how much has the blocking of 100km of ditches raised the water table by?
2.65cm
How was the changes in the water table measured?
Using dip wells
How do dip wells work?
They are inserted into the ground and when they make contact with water, a buzzer or light is activated and a depth measurements can be taken
