Demand for water is effected by many external factors such as technological development,

political, institutional and financial conditions, and

climate change.





Global population is projected to reach 9.3 billion in 2050

UNDESA ). Population growth leads to increased

water demand, reflecting growing needs for drinking

water, health and sanitation, as well as for energy, food

and other goods and services that require water for

their production and delivery.





Urban areas of the world,

particularly those in developing countries, are expected

to absorb all this population growth, at the same time

drawing in some of the rural population. This intense

urbanization will increase demand for water supply,

sanitation services and electricity for domestic purposes





Water of acceptable quality and in adequate quantity is

needed to meet food production demands. At the same

time, food production and supply have a negative impact

on the sustainability and quality of water resources.





Agriculture is the biggest water user, with irrigation

accounting for 70% of global water withdrawals

. With increasing demand for food, competition for

water is rising. Specialized crops and livestock products

often require more water (and in most cases more energy)

to produce and lead to higher levels of water pollution.





In

the pursuit of food security, technological advancements

in the agricultural sector could have significant impacts,

both positive and negative, on water demand, supply and

quality.









Climate change impacts the hydrological cycle and

consequently impacts water resources. It is an additional

stressor through its effects on other external pressures

and thus acts as an amplifier of the already intense

competition for water resources.





For example, higher

temperatures and an increase in the rate of evaporation

may affect water supplies directly and potentially

increase the water demand for agriculture and energy.





Significant levels of uncertainty exist with respect to

climate change projections, and these uncertainties

increase greatly when focusing on local scales.





Water

resources management is in a difficult transition phase,

trying to accommodate large uncertainties associated

with climate change while struggling to implement

a difficult set of principles and institutional changes.





Consumer demand and increasing standards of living are driving

increased demand for water, most notably by middle income households in developing and emerging economies through their greater demand for food, energy and other goods, the production

of which can require significant quantities of water ( IEA ).

According to the OECD , in the absence of new policies

(i.e. the Baseline Scenario), freshwater availability will be

increasingly strained through 2050, with 2.3 billion more

people than today (in total more than 40% of the global

population) projected to be living in areas subjected to

severe water stress, especially in North and South Africa

and South and Central Asia.





Global water demand in terms

of water withdrawals is projected to increase by some 55%

due to growing demands from manufacturing (400%),

thermal electricity generation (140%) and domestic use





While data on precipitation – which can be measured with

relative ease – are generally available for most countries,

river runoff and groundwater levels are generally much

more difficult and costly to monitor.





As a result, trends

regarding changes in the overall availability of freshwater

supplies are difficult to determine in all but a few places in

the world. However, it is clear that several countries face

varying degrees of water scarcity, stress or vulnerability.





In the absence of flow regulation by artificial storage

infrastructure, the availability of surface water varies from

place to place across days, seasons, years and decades as

a function of climate variability.





Climate change means

past hydrological trends are no longer indicative of future

water availability. According to the most recent climate

projections from the Intergovernmental Panel on Climate

Change ( IPCC ), dry regions are to a large extent

expected to get drier and wet regions are expected to

get wetter, and overall variability will increase.





There is

mounting evidence that this is indeed happening as a

result of an intensification of the water cycle

and it is affecting local regional water supplies,

including those available for energy production.





There is clear evidence that groundwater supplies are

diminishing, with an estimated 20% of the world’s aquifers

being over exploited, some massively so

.





Globally, the rate of groundwater abstraction

is increasing by 1% to 2% per year ( WWAP , 2012),

adding to water stress in several areas and

compromising the availability of groundwater to serve as

a buffer against local supply shortages.





Water quality is also a key determinant of water

availability, although potable water is not required

for all purposes. Polluted (or saline) water cannot be

used for several crucial purposes such as drinking and

hygiene.





However, for other purposes such as agriculture

and certain industries, use of slightly polluted water

or partially treated waste water can be considered. This

provides an opportunity to use reclaimed waste water and

storm water, reducing the cost and energy consumption

associated with water treatment.





Although there have been some local successes in

improving water quality (mainly in developed countries),

there are no data to suggest an overall improvement in

water quality at the global scale. Deterioration of wetlands

worldwide further contributes to reduced potential in

ecosystems’ capacity to purify water.





It is estimated that

more than 80% of used water worldwide – and up to 90%

in developing countries – is neither collected nor treated

WWAP , 2012), threatening human and environmental 2012), threatening human and environmental

health.





Source: United Nations



