case study - river exe Flashcards
describe where the river exe starts, runs through and finishes
source in exmoor hills, down through exeter to the sea at exmouth in south coast of Devon
how long does it flow for
96km
where is the gauging station and what is it called?
in the upper catchment area - Thoverton
how large is the catchment area?
601km2
what’s the land elevation like in the north compared to the south of the upper catchment?
north - high elevation
south - much flatter
what’s the majority of the rock like under the catchment area?
impermeable (mainly Devonian sandstone)
what is the majority of the land in the catchment area like?
agricultural grassland
what is the high ground in Exmoor like?
lots of peat bogs and moors
rainfall is high over Exmoor, what is most of this rain absorbed by?
peatbogs
give 2 reasons surface runoff accounts for 65% of the water balance:
-most bedrock = impermeable -> reducing percolation + baseflow
-drainage ditches on exmoor reduces soil water storage
which 2 developments have affected the water cycle of the river exe?
-restoration of peat bogs
-Wimblefall Reservoir
what are three useful benefits of the wimblefall reservoir?
-supplies water to exeter
-regulates water flow
-prevents peaks and troughs which would otherwise make flooding/drought more likely
why did the peatlands need restoring on exmoor?
-drainage ditches scarred the landscape
-increased water flow speed to river exe, reducing water quality -carries more silt
-peat dries out - decomposes releasing co2 and methane
how is the project restoring peat bogs in exmoor?
by blocking drainage ditches
what are some successes of the peatland restoration?
1- increases water content
2- helps restore carbon in the peat
3- improved water quality - slower through flow, less sediment carried into rivers
