RIVER EXE Flashcards
how long is the river exe
82.7km long
where is the river located
south-coast of Devon
where is the source of the river
hills of Exmoor
what towns/cities does the river flow through
Tiverton and Exeter, to the sea at Exmouth
features of the river
it has an extensive network of tributaries and a high drainage density
what is the size of the upper catchment
601km2
what is the maximum elevation
514m is in the north
what is the topography like in the south
the land is much flatter in the south – the lowest elevation = 26m
what’s the geology like here
84.4% of the catchment is underlain by impermeable rocks – predominantly Devonian sandstones, accounting for the extensive drainage network
how much of the land is being used for agricultural grassland?
67%
how much of the land is woodland
15%
where does arable farming take place
high grounds of exmoor
what % of land do moors, peatbogs and arable farming account for
3
when was the wimbleball reservoir built
1979
what two rivers were dammed by this reservoir
the River Haddeo, and upland tributary of the River Exe
what is the total surface area covered by the reservoir
150 hectares – approximately 150 football pitches
where does the reservoir supply water to
exeter and all parts of east devon
what does the reservoir do
regulates water flow, ensuring steady flow regime during the year
prevents peaks and troughs of water discharge that make flooding or droughts more likely
why is there a need for the exmoor peatland restoration project
drainage ditches dug in peat bogs of Exmoor = farming
= increased the speed of water flow to the Exe, which reduces water quality as more silt is carried downstream
peat = dug as a fuel
peat dries = decomposition = releasing carbon from its store = CO2 and methane
what does the exmoor mire project do
works to restore the peat bogs by blocking the drainage ditches with peat blocks or moorland bales.
= increases water content and returns the ground to the saturated, boggy conditions that would naturally occur in this moorland = conditions help to retain C stored within peat
exmoor mires project
aims to restore 20,000ha of Exmoor to the boggy conditions that would naturally be present by blocking drainage ditches with peat blocks and moorland bales.
benefits of the project
more water storage catchments – water transfer is slowed, increasing storage capacity and ensuring a steady supply of water throughout the year.
improved water quality – slower through flow means that less sediment is carried into the rivers. Water is cleaner, less expensive to treat and good for wildlife such as salmon.
more carbon storage – peat is essentially carbon and water and therefore an important carbon store. Dry peat releases carbon dioxide through oxidation. By encouraging the rewetting of peat and active peat growth, carbon dioxide is naturally absorbed from the atmosphere and stored.
Improved opportunities for education, leisure and recreation. Peatland habitats are very biodiverse, with many species of plants, birds, butterflies and insects.
Improved grazing and water supply for animals – animals benefit from having year round drinking water as well as improved grazing during the drier parts of the year.
what happened in 2015
1000+ ha of peat moorland had been restored and nearly 100km of ditches blocked, raising the water table by 2.65cm
his has reduced the amount of water that drains by 2/3 in this area.
what % of the land use is woodland/grassland
82%
what type of rock is the catchment mainly underlain with
impermeable rock
what drains the peat lands
extensive network of ditches
where is wimble ball built
on an upland tributary of the river exe
