4.2 Water Supply and Water Scarcity

Figure 4.2.1 Water Supply of a selection of countries [see reference 7]

Figure 4.2.1 sourced from The ImpEE Project, The Cambridge-MIT institute. The ImpEE wesbite is designed as an educational resource. It may be reproduced, modified and used freely for educational purposes
http://www-g.eng.cam.ac.uk/impee/?section=topics&topic=water&page=slideshow

In many countries, only a very small proportion of available water is actually extracted for use. The total resource that is available to a country or a region is usually termed the ‘supply’. The amount that we extract for use is termed the ‘withdrawal’.

Figure 4.2.2 Water Scarcity – Annual Renewable freshwater availability for a selection of countries, with limits shown different levels of water scarcity [See references 8,9,10]

Figure 4.2.2 sourced from The ImpEE Project, The Cambridge-MIT institute. The ImpEE wesbite is designed as an educational resource. It may be reproduced, modified and used freely for educational purposes
http://www-g.eng.cam.ac.uk/impee/?section=topics&topic=water&page=slideshow
 

The figure above shows the availability of fresh water for a selection of countries. Highlighted on the graph are levels of regular, chronic and absolute water scarcity. The table below outlines the figures for these levels. 18 countries are in the absolute scarcity category, and a further 4 have chronic water scarcity status.

Table 4.2.1 Water stress and scarcity categories [see reference 11]

Annual renewable fresh Water
Cubic metres per capita per year	Cubic metres per capita per day	Level of water stress
>1,700 /	4.65	Occasional or local water stress
1,000 – 1,700	2.74 - 4.65	Regular water stress
500 – 1,000	1.36 - 2.74	Chronic water scarcity (lack of water begins to hamper economic development and human health and well-being)
<500	1.36	Absolute water scarcity

Table 4.2.1 sourced from The ImpEE Project, The Cambridge-MIT institute. The ImpEE wesbite is designed as an educational resource. It may be reproduced, modified and used freely for educational purposes
http://www-g.eng.cam.ac.uk/impee/?section=topics&topic=water&page=slideshow

By widely-used water stress definitions, the UK is currently subject to occasional or local water stress. This is evident from our infrequent experiences of hosepipe bans and

pleas for water conservation from water companies. As climate changes and precipitation patterns alter, the occurrence of water stress is predicted to become more widespread. This, combined with population increases in many places, will result in more extensive water shortages relative to demand. As with all country data this is aggregated average information. Within these countries, particular regions may be relatively more water-rich or water-poor. For example, the South East of England is considerably more water-stressed than Northern Scotland.

Definitions

It is important to get a feel for what this actually means. Absolute scarcity in these terms (500m³/person/year) is less than 1.5 cubic meters of water per person per day. This seems like a lot, but usually we are only thinking about the domestic portion of water use rather than the per capita water availability necessary to maintain a functioning economy. Lack of water availability can inhibit industrial and economic development.

For general human health requirements, volumes required are as follow:

• Normal Recommended 50 litres per person per day
• Minimum Recommended 30 litres per person per day (5 litres for cooking and drinking, 25 litres for hygiene)
• Emergency Sphere guidelines 15 litres per person per day [see reference 12]

Some of the most water scarce countries are small island nations such as Malta (50m³/capita/year) and the Maldives (105m³/capita/year), Singapore (144m³/capita/year), and those of the Middle East region: Kuwait (10), UAE (66), Libya (108), Saudi Arabia (109), Bahrain (149), Qatar (164), Jordan (174), Yemen (220), Israel (339). High demand for industrial purposes and meeting domestic needs of increasing populations lead to over-use of water in some of these places.