Flashcards
the river exe
Cards in this deck (13)
- 1where is the river exe?- SW england, south coast of devon
- flows 82.7km north to south from Exmoor to Exmouth, though Tiverton and Exeter
- has an extensive network of tributaries - 2what are the characteristics of the river exe?- PHYSICAL, area of upper catchment=601km2, maximum eleviation of 514m in N, land flatter in S @ 26m
- GEOLOGY, estimated 84.4% of catchment underlined by impermeable rocks, mainly devonian sandstones, accounts for extensive drainage
- LAND USE, most agri grassland (67%), some woodland (15%) and arable farming, on high ground exmoor moors&peat bogs - 3water balance on the river exe..precipitation (1295)= eval +/- soil water storage (451) + runoff (844)
- rainfall= high, especially over exmoor, steep relief, much absorbed by peaty moorland soils but if saturated water flows off hills rapidly
- run off accounts for 65% water balance, quit high to other UK rivers.. reasons why:
..impermeable nature of most bedrock (no deep groundwater stores) means less percolation&baseflow
..drainage ditches on exmoor reduce amount of soil water storage
- it has been significantly affected by the construction of WIMBLEBALL RESERVOIR & peatland restoration on exmoor - 4discharge for the river exe..lower compared to other UK rivers, within devon reflects exe responds slowly to rainfall events, after flooding discharge recedes slowly
- 5what is the exmoor mires project?- aims to restore 2000ha of exmoor to boggy conditions that would naturally be present by blocking drainage ditches with peat blocks
- 6what are the benefits of the project?- more water storage in upper catchments
-improved water quality
- more carbon storage
- improved opportunities for education, leisure & resurrection
- improves grazing & water supply for animals - 7how has it helped to ensure sustainable water supply?- less money spent on filtering water as if slowed down then better quality
- water table remains high & so groundwater stores increase, good for providing water - 8how has it helped to increase the carbon storage?by putting peak blocks/moorland bales to block drainage ditches, ground is retuned to saturated conditions that help retain carbon stores within peat
- 9what is the process?- scientists have established 3 experimental stations, involving installation of dip well transects across newly blocked ditches
- an electric diameter records depth of water table, inserted into dip well & when electrodes touch water buzzer/light activated & depth taken - 10has it had an effect?- byt 2015 over 100-ha of peat moorland restored and almost 100km of ditches blocked..raising water table by 2.65m
- has reduced amount of water that drains from monitoring area by two thirds - 11what is the wimbleball reservoir, its impact, etc?- river haddee (upland tributary) was damned to create reservoir
= 150 hectares
- supplies water to exeter & parts of east devon, regulates water flow ensuring steady regime during yr, preventing troughs&peaks of discharge make flooding&drought more likely - 12how has it helped to ensure sustainable water supply?- supplies water to exeter & east devon
- regulates water flow
- controls water downstream - 13what effect do the large settlements have?e.g. Exeter, Tiverton
- increased amount of impermeable surfaces
- 2000-5000 homes in lower catchment are at risk from flooding
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- GCSE Geography (water and carbon cycles) Flashcards on the river exe, created by serena norman thomas on 25/06/2017.
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- serena norman thomas
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