River Catchment - Mersey

Question 1

Inputs into catchment

Answer 1

Rain
Channel flow from upstream
Surface runoff
Throughflow

Question 2

Outputs out of catchment

Answer 2

Evaporation

Channel flow down stream

Question 3

How many miles ?

Answer 3

70 miles from source

Question 4

Cities it flows through

Answer 4

Manchester
Sale
Liverpool

Question 5

What it 1.45 miles south east of Mersey

Answer 5

Flixton girls school

Question 6

Stores of water in catchment

Answer 6

Reservoirs

Ridgegate

Question 7

What rivers is the upper Mersey catchment made of?

Answer 7

Mersey
Tane
Goyt

Question 8

Where is rural land located

Answer 8

Uplands to the east

Question 9

Where is urbanised land located ?

Answer 9

Lower catchment to west

Question 10

Bedrock in the catchment

Answer 10

The most permeable rock was in the west but now it has been urbanised.

Rural areas in east there is permeable rock eg peat that water can infiltrate onto this allows for steady drainage of water back into river

Question 11

Rainfall in the area

Answer 11

Rainfall above average of 926mm

Highest rainfall in east where rural higher than is - indicates relief rainfall
water flows quickly as surface run off down steep slopes - less through flow

Rainfall increased from 1941-1990

Question 12

To the west

Answer 12

Initially was the most permeable rock meaning infiltration / percolation / interception could occur but not heavily urbanised meaning rain flows as overland flow/ surface runoff quickly into channel - flashy HG

Question 13

To the east

Answer 13

Permeable land
Mountains / heath / pest
Lots of infiltration/ interception / percolation
Less overland flow meaning water steadily flows into channel - subdued HG

Question 14

What has increased flow in the river ?

Answer 14

Channelising the river, quick velocity as water course is straight

Question 15

Why is the area flooding?

Answer 15

Heavy rain.

Urbanised areas - more surface runoff less infiltration.

Question 16

Example of flooding

Answer 16

Upper merysey 1965

Breached its banks causing widespread damage to livestock

Question 17

Why do we need to manage the area?

Answer 17

Heavily populated about 70% of the upper catchment is populated

Flooding is known to occur in urban areas as a result of short intense storms when capacity of drainage system is exceeded and water forced to flow across ground

Question 18

Normal level of the Mersey at Ashton weir in average weather

Answer 18

0.31m and 0.37m

Question 19

Highest ever level at Ashton weir recorded

Answer 19

3.64m on 6th nov2000

Question 20

Name a location with over 500 properties at risk

Answer 20

Didsbury

Question 21

Engineering schemes in upper Mersey

Answer 21

£22 million pound invested in last 10 years on flood alleviation schemes.

Over 67km raised flood defence

Storage in places like sale - reduce peak flow of 35%

Question 22

Activities reducing probability of flooding

Answer 22

Maintaining / improving flood defences / structures

Working with local authorities - land use management as golf courses can be built on flood plain not houses

Question 23

Activities reducing consequence of flooding

Answer 23

Flood risk mapping

Warning services

Promoting awareness

Question 24

Name 3 factors which will impact flooding in future

Answer 24

Climate change
Change in land use
Rural land management

Question 25

How is climate change going to impact flooding in future

Answer 25

Frequent/ intense storms

Wetter winters

Question 26

Future scenarios in upper catchment

Answer 26

20% increase in peak flow

By 2100 the number of properties at risk of fluvial flooding will be increased by around 11% to 300 properties

In some areas the number of properties at risk in 1% AEP could increase up to 77% higher

Question 27

Physical impacts affecting drainage basin

Answer 27

Permeable surfaces.

Vegetation.

Steep slopes.

Rock type.

Question 28

Human factors affecting river discharge

Answer 28

Urbanisation

Engineering