River Exe

Question 1

Climate and Weather

Answer 1

Summer - Comfortable & Cloudy
Winter - Cold & Wet
Temps from 3-20 Degrees
Rainfall Peak Oct-Jan
Temp Peak June-August
November has avg rainfall of 82mm
April has avg rainfall of 43mm
0% humidity

Question 2

Geology and Land Use

Answer 2

93.5% of bedrock is moderate or low permeabiliy - lots of surface runoff
84.4% of ground underlaid by impermeable rock (sandstone)
57% Grassland
85% Agricultural
13% Woodland - not much interception and not much transpiration

Question 3

Water Balance Detail

Answer 3

Moors have steep gradient - large amount of overflow
Peaty moors absorb a lot of rainfall (Exmoor)
Runoff accounts for 65% of water balance
High rainfall
Drainage ditches used to mitigate flooding
By 2015 over 1000 hectares of peat moorland had been restored
Discharge - between 0.23m and 2m (90% of monitoring time) - Maintained at constant level by Wimbleball Reservoir (1979)
- Highest level at 3.64m in 1960

Question 4

Urban Settlements

Answer 4

Exeter, Exmouth and Tiverton - Risk of Flooding
11000 properties at risk
Exeter has high population density - risk

Question 5

River Regime

Answer 5

River flow at its lowest between Jul-Oct
+ Highest in Dec
High Rainfall in Winter, Less Discharge in Summer
Flashy Regime
Relief Rainfall
Time Between Peak Rainfall and Peak Discharge is Short

Question 6

Flooding

Answer 6

Large flooding takes place every century
Long periods of rainfall saturate catchment
Tide-locking tributaries has caused problems
Flooding has greatly reduced over time due to practices put in place

Question 7

Wimbleball Reservoir

Answer 7

Tributary of river exe dammed with reservoir in 1979
Ensures steady flow of regime year round and prevents peaks and troughs in discharge
120 million litres of water held within reservoir
Surface Area of 150 hectares
Supplies water to Exeter and parts of East Devon

Question 8

Human Impacts

Answer 8

Mainly positive
Moorland drainages (water goes to river instead of moorland)
Peatland restoration (exmoor mires project) - increased water content which saturates them and retains more/releases less carbon
Water in river contains less silt, which makes water treatment 20% cheaper
All decreases surface runoff and therefore less flooding

Question 9

Exmoor Mires Project

Answer 9

Aims to restore boggy conditions by blocking drainage basins
Benefits:
More water storage in upper river catchment
Improved water quality
More carbon storage