Supply and Demand for Resources TAKE NOTES
There is no substitute for water. Without water there is no food, and agriculture already consumes 70 per cent of the world’s fresh water. Every type of food production — cropping, grazing and processing — requires water. Thus, a lack of water is possibly the most limiting factor for increasing food production in future.
To feed an additional two billion people by 2050, the world will need to generate more food and use more water. The two main concerns that threaten future water security are water quantity and water quality (see figure 1). |
Why the low water though?
In theory, the world has enough water; it is just not available where we want it or when we want it, and it is not easy to move from place to place. We already use the most accessible surface water, and now we are looking for it beneath our feet. Underground aquifers hold 100 times more water than surface rivers and lakes. However, groundwater is not always used at a sustainable rate, with extraction exceeding natural recharge, or filling. This occurs in many of the world’s major food-producing places, in countries such as the United States, China and India.
Water insecurity is connected with food insecurity. Figure 2 shows the predicted number of people who will face water stress and water scarcity in the future. A more complex view is seen in figure 3, which shows an interconnection between increased demand for water and predicted climate change, population increase and greater industrialisation in the 2050s.
When water availability drops below 1.5 million litres per person per year, a country needs to start importing food, although that makes the country susceptible to changes in global prices.
Developing countries that experience water stress cannot afford to import food. They are also more vulnerable to environmental disasters. Seventy per cent of food emergencies in developing countries are brought on by drought.
Why is there a water shortage?
The main causes of the growing water shortage are outlined below.
• Food production. It is estimated that an additional
6000 cubic kilometres of fresh water will be needed for irrigation to meet future food demand. Changes in diet, especially increased meat consumption, require more water to grow the crops and pasture that feed the animals. A typical meat eater’s diet requires double the amount of water that a vegetarian diet requires.
• Growth of urban and industrial demand. Water for farming is diverted to urban populations, and productive land is converted to urban use.
• Poor farming practices. Water is wasted through inefficient irrigation methods and cultivating water-hungry crops such as rice. Poorly maintained irrigation infrastructure, such as pipes, canals and pumps, creates leakage.
Over-extraction. Improved technology and cheaper, more available energy have enabled us to pump more groundwater from deeper aquifers. This is not always done at a sustainable rate, so as water is removed, less is available to refill lakes, rivers and wetlands.
• Poor management. Governments often price water cheaply, so irrigation schemes use water unsustainably. Some countries may have available water but lack the money to develop irrigation schemes.
Questions
1a) Examine figure 2 and describe the projected changes in the number of people affected by water stress between 1990 and 2050. Use figures in your description.
b) How do these changes compare with figures for water scarcity?
2 If a country has an average of 0.5 to <1.0 million litres of water per person, per year, would they be considered to be water stressed? Why?
3 Why is agriculture both a contributor and a victim of water pollution?
EXPLAIN
4 a Refer to figure 3. Describe those places in the world that are predicted to be in high to extreme water stress in the 2050s.
b Compare your answer with a map of world average rainfall (Google search this). Are areas that are predicted to be suffering high to extreme stress by 2050 also areas of low rainfall?
c How could you explain why places like eastern Europe could face water scarcity?