Water Security

Question 1

Define water security

Answer 1

Obtaining and managing sufficient water of a high enough quality ton meet current and likely future needs, without compromising activities and/or the environment

Question 2

Give the 3 aspects of water security

Answer 2

Social - clean/healthy to drink

Economy - Affordable + sufficient for industrial activities

Environmental - Must not contaminate natural systems

Question 3

…/10 households worldwide lack water security

Answer 3

3/10

Question 4

What percentage of water is in the oceans

Answer 4

97. 5%

2. 5% = freshwater

Question 5

What percentage of freshwater is easily accessible

Answer 5

1%

Question 6

What is the largest source of accessible freshwater

Answer 6

Lakes - 52%

Question 7

Give 7 sources of water

Answer 7

River abstraction

Reservoir

Borehole

Pumping from aquifers

Glacial meltwater

Desalination

Recycled

Question 8

Describe River abstraction

Answer 8

Oldest way humans have obtained water

Thames water (serving London + southeast) obtains 70% of its water from rivers

Question 9

Describe Reservoirs as a water source

Answer 9

Storage lakes (Man-made/natural) that hold quantities of river flow such that it is subject to less short term fluctuations than a river level

Question 10

Describe boreholes

Answer 10

Traditional walls are sunk through permeable surface layers to penetrate the water table contained in rock structures with water-holding capacity

Thames water = 30% water this way

Question 11

Describe pumping from aquifers

Answer 11

An aquifer is a confined layer of saturated rock, usually deeper than the water table, and capped top and bottom by impermeable rock

When it is bored into, the substantial pressure forces the water to rise

Question 12

Describe glacial meltwater

Answer 12

60% Iran’s freshwater comes from melting glaciers

Climate change poses serious issues for the medium term sustainability of this water source

The meltwater form glaciers in the Himalayas supplements several great rivers, such as the Ganges and Indus

Question 13

Describe desalination

Answer 13

The evaporation of seawater to distil freshwater requires substantial energy input and produces salt as a by product

Modern plants use reverse osmosis

Israel gets 40% freshwater form desalination

Question 14

Describe recycled water as a water source

Answer 14

As demand for freshwater intensifies, it is increasingly being recycled

In the valley of Mexico, approximately 90% of irrigation is resumed water form Mexico City

Question 15

Define water surplus

Answer 15

Having more water than is needed

E.g - Wales - net exporter of water to England

Question 16

Define water stress

Answer 16

Water supply periodically compromised

Occurs when there is less than 1700m³ litres available per person per year

May arise due to growing population demand, reduced water supply, or contamination of water supply

Question 17

Define water scarcity

Answer 17

Insuffiecnt water to meet all human demands

Occurs when their is less than 1000m³ litres available per person per year

20% world’s population experience this and are forced to use water of poorer quality/use less

Question 18

Define water crises

Answer 18

People don’t have access to potable water of sufficient quality or quantity to meet basic needs

Consequences =

• Human health deteriorates due to using contaminated sources
• Disease spreads due to unsatisfactory sanitary conditions
• Social disruptions as many hours each day dedicated to obtaining water

Question 19

Where is the world’s most water stressed area

Answer 19

Middle East

Averages 1200m³ water per person/year

Question 20

Describe Singapore water situation

Answer 20

High potential for water stress as demand exceeds natural supply

However, does not mean hat there is water scarcity as Singapore is an exceptional water manager

• Technology
• International agreements
• Management
• Rainfall capture systems
• Desalination plants

Question 21

Give some physical factors that influence water supply

Answer 21

• Climate determines the global distribution fo water supply by means of annual and seasonal distribution of precipitation
• Precipitation varies globally, not only in terms of amounts, but also seal ditrabuton, availability and reliability

Question 22

How does climate affect water supply

Answer 22

Precipitation is the paramount factor influencing water supply at a global scale. The average amount is around 860mm / year but this can vary greatly

Temperatures also influence rates of evaporation. High temperatures and intense sunshine can evaporate considerable amounts from the surface of water bodies, e.g. Lakes and river

Question 23

How does geology affect water supply

Answer 23

Geology controls the distribution of aquifers that provide groundwater storage

Some rocks (e.g. Chalk) are permeable and can provide groundwater supplies.
Impermeable lithology is more likely to generate surface flow in the form of streams and rivers.

Aquifers usually form in sedimentary basins, subject to variable layers of permeable and impermeable rock

Question 24

How does drainage and relief affect water supply

Answer 24

River systems and surface water (drainage) are a function of climate, relief, vegetation and geology

Gentle relief allows more time for water to infiltrate and contribute to groundwater. It is also more likely to lead to natural lakes. Steep relief generates faster flows.

Natural vegetation can also influence drainage: by intercepting rainfall, impeding surface flows or absorbing water via root systems.

Question 25

Give an example of climate affecting water supply

Answer 25

The record high for average annual rainfall is at Mt Waialeale in Hawaii at 114,000 mm whereas the record lowest is in the Atacama desert in Chile, where no rain fell for 14 years

Question 26

Give an example of geology affecting water supply

Answer 26

Greater London draws on water from the chalk aquifer beneath it. This is recharged by rainfall falling on the North Downs and Chiltern Hills.

Question 27

Give an example of drainage and relief affecting water supply

Answer 27

The Amazon has an average discharge of 175,000 m3/sec from its catchment area of 6,915,000 km2. It generates its own microclimate through massive evapotranspiration that seeds more precipitation on route.