The London Basin (Thames)

Question 1

How many separate river systems does the UK have?

Answer 1

1,500

Question 2

What percentage of rivers can be said to be in their natural state?

Answer 2

15%

Question 3

What is the catchment area of the Ock and Lambourn river basins?

Answer 3

234km2

Question 4

What is the mean flow of the Ock river basin and the mean flow of the Lambourn river basin?

Answer 4

Ock - 1.578m3/s
Lambourn - 1.758m3/s

Question 5

What is the type of aquifer situated under London?

Answer 5

Chalk syncline

Question 6

How did abstraction affect groundwater levels and what did this cause?

Answer 6

Groundwater levels fell by 88m and this resulted in a localised cone of depression.

Question 7

What was the rate of groundwater recharge by the 1990s?

Answer 7

3m/year

Question 8

What is GARDIT?

Answer 8

The General Aquifer Research, Development Investigation Team - which led the careful management of the syncline and artificial recharge to minimise the damage the groundwater recharge would have caused.

Question 9

What threat does the aquifer face in East London?

Answer 9

Saline intrusions

Question 10

How many people does the Thames support?

Answer 10

13 million

Question 11

What percentage of public water supplies comes from groundwater sources.

Answer 11

40%

Question 12

What is the Thames Gateway?

Answer 12

The largest regeneration project in Europe - to redevelop 70km stretch of the Thames basin.

Question 13

How many people will be affected in the Thames basin due to rising sea levels?

Answer 13

Environmental Agency estimates around 300,000 homes are at risk.

Question 14

What flood management scheme is being used further up the River Thames?

Answer 14

The Oxford Flood Alleviation Scheme. To protect second fastest growing economy in the country. PLANS - river dredging, improved urban drainage, lowering the flood plain, flood relief channels, flood plain restoration and land use zoning.

Question 15

What is the Thames Barrier?

Answer 15

Crosses a 520m section of the Thames. Gates are 20m high and can hold back 9 tons of water. Protects London from tidal waters which would slow down river drainage.

Question 16

What is the Oxford Flood Alleviation Scheme’s aim?

Answer 16

Creating new wetland wildlife corridor - manages river overflow and stops flooding in high land value areas. Reduces hard engineering. Projected to cost £150 million. BUT will save £1.4 billion in damages over next 100 years.