WATER SCARCITY

Water stress and Water scarcity occur when the demand for water exceeds the available amount during a certain period or when poor quality restricts its use.

The UN states by 2025, 1.8 billion people will be living in countries or regions with absolute water scarcity, Two-thirds of the world population could be under stress conditions

"water stress" is when annual water supplies drop below 1,700 cubic meters per person per year, according to the Falkenmark Water Stress Indicator

PHYSICAL SCARCITY When consumption exceeds 60% of the usable supply Physical access to water is limited. It is when the demand outstrips the lands ability to provide the needed water. For the most part, dry parts of the world or arid regions are most often associated with physical scarcity.

ECONOMIC SCARCITY Where a country has sufficient water resources but additional storage and transport facilities are required making it expensive When a population does not have the necessary monetary means to utilize an adequate source of water. It is about a unequal distribution of resources for many reasons, including political and ethnic conflict.

Task Decide if the following supply issues are environmentally or human induced.

SUPPLY ISSUES

Inaccessible or Out of Reach India gets 90% of its rainfall during the monsoon season and at other times rainfall over much of the country is very low. Sub-Saharan Countries rely on large and expensive water development projects.

No infrastructure The addition of water to areas where it is insufficient for adequate crop growth. – types can range from total flooding such as in paddy fields to drip irrigation where precise measurements are distributed to each plant.

Rain: About three-quarters of the annual rainfall occurs in areas containing less than one-third of the world’s population, whereas two-thirds of the world’s population live in the areas receiving only one-quarter of the world’s annual rainfall

Evapo-transpiration: The water supply depends on several factors in the water cycle including evaporation and transpiration rates. Climate scientists say that the greenhouse effect is accelerating the global water cycle. "It's like the rich get richer scenario where the wet places will get wetter and the dry places will get a lot drier because the conveyor belt is speeding up between those two places.” Source ABC Science:

Fossilized Aquifers are rocks that hold water. They provide an important store of water that regulates the hydrological cycle and maintains river flow. Their resources are being depleted.

Wetlands (land with soil that is permanently flooded) During the past centaury half of the worlds natural wetlands have dried up.

Pollution Ground water pollution has been on the increase and can happen naturally such as naturally occurring arsenic in groundwater pumped up through tube wells in Bangladesh. After realising that 85 million of the country’s 125 million population will be affected, Bangladesh has sunk millions of wells in the last 30 years in order to provide a supply of drinking water free from the bacterial contamination of surface water.

DEMAND FOR WATER Water is one of the most sensitive and unsolvable problems in the Middle East, Africa and South Asia. It is likely that disputes over scarce water resources will fuel and increase armed conflicts.

POPULATION INCREASE Population, urbanization and industrialization have increased the use of water in these sectors. As world population and industry has increased the use of water has acceleratedand this is projected to continue. By 2025 global availibility of fresh water may drop to by 25% of the 2000 figure.

Agriculture Agriculture is the largest user consuming almost two-thirds of all water drawn from rivers, lakes and ground water. Scince 1960, water use for crop irrigation has risen from 60-70%. Industry uses about 20% of available water, and the municipal sector uses 10% Exam question: Describe two pollutants which are causes of unsafe drinking water (4 marks)

LIFESTYLE

(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3) Current Water Stress

(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3) Water-Stress Effects AmountTiming - seasonality - drought - flood Quality - salinity - nutrients - temperature - toxins - pathogens - sediments

(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3) Exam question:  ‘The factors affecting patterns and trends in physical water scarcity are environmental rather than human.’ Discuss this statement.