river Exe

Question 1

background

Answer 1

Devon
area of 601km, 87.5km long
underlain by over 84% impermeable sandstone
runoff accounts for 65% of water balance

Question 2

background on the Wimbleball reservoir

Answer 2

built in 1979 along the tributary, River Haddeo
forms a reservoir with a net storage of 21,320 megalitres and surface area of 150 hectares
> creation of a new store of water
provides water for Tiverton and nearby Exeter

Question 3

Impacts of the wimbleball reservoir?

Answer 3

● peak discharge lowered, regulates and controls discharge throughout the year,
● helps meet water demand providing security
● reduces likelihood of flooding

Question 4

effects of drainage ditches…. stats pls

Answer 4

POSITIVES
creates less saturated, more fertile farmland, began after WWII to make farming more productive.
The peat also used as fuel and as fertiliser
NEGATIVES
this causes the mires to dry out, reducing water table/depleting the groundwater stores and increasing runoff/ discharge of Exe, affecting the water supply
depletion of soil water stores, peat is more easily erodable and increases overland flow as less percolation occurs
oxidation of exposed peat bogs, releasing large quantities of carbon into the atmosphere (STORE TO SINK)
physically scarred the landscape and reduced biodiversity of the area

Question 5

aim of the Exmoor Mires project

Answer 5

restore the peat bogs to their natural condition
by blocing 2000a of peat moorland with peat bales
by 2015, 1000 ha restored, raising water table by 2.65cm
shows that the impacts of drainage ditch is reversible

Question 6

what impact has the work done by the project had?

Answer 6

• floods less likely, reduced soil erosion and the amount of silt entering the rivers
• minimising flood damage as less likekly that the capacity of the river is exceeded
• water naturally filtered through the vegetated peat instead of leaching straight to the river

Question 7

what is a benefit of reduced amount of silt entering rivers

Answer 7

water is 20% less expensive to treat

water quality is improved as a result of the restored peat

Question 8

land use of exmoor mires

Answer 8

67% agricultural
15% woodland
13% moor and peat bogs

Question 9

how do physical factors affect the drainage basin?

Answer 9

● RELIEF Steep slopes increase the speed water gets to the river
● GEOGLOGY impermeable rocks reduce infiltration, increasing runoff and therefore the speed the water reaches the river
● AREA Small area means water has less distance to travel to get to the river so runoff is faster

Question 10

Name 3 ways in which Human activity has affected the drainage basin

Answer 10

● building of reservoir
● drainage of the mires
● Resoration of peat bogs