Globale og regionale perspektiver for tilgjengelighet,

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Globale og regionale perspektiver for
tilgjengelighet, behov og utnytting av
vannressurser eller Global and regional
perspectives on availability, demand and
exploitation of water resources
Professor Ånund Killingtveit Institutt for
vassbygging Fakultet for bygg- og
miljøteknikk NTNU
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• Main topics in the presentation
• Water - the global perspective
• Available water resources
• Trends in water consumption
• Regional perspectives on water scarcity
• About sustainable water use
• The need for Water Balance Policy
• Three examples of non-sustainable water use
• Summary and conclusions

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World water resources water in stock
A number of attempts have been made to assess the
global water balance, here the figures published
by World Resources Institute (WRI, 1988) are used
The Global perspective
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Flows of the global water cycle (km3/yr) (data
from Shiklomanov (1992) WRI (1998))
The Global perspective
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Flows of the global water cycle (km3/yr) (data
from Shiklomanov (1992) WRI (1998))
The Global perspective
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Useful flows of the global water cycle
(km3/yr) (data from Shiklomanov (1992) WRI
(1998))
The Global perspective
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The uneven distribution the main problem

• The average water availability figures gives a
  misleading picture
• Water is determined by global and regional
  precipitation distribution
• and therefore the water resources vary widely
• Spatially (from rainforests to deserts)
• Temporally (seasonally and between years)

The Global perspective
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Global runoff distribution, specific runoff
The Global perspective
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Global runoff distribution, total volume
The Global perspective
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Global runoff distribution, pr. capita
The Global perspective
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Water use main categories

• Agriculture (Irrigation)
• Reservoirs (Evaporation losses)
• Municipal water supply (drinking water)
• Industry (Process water)
• Resipient of waste (wastewater, thermal
  pollution)
• Energy (Hydropower, cooling water)
• Aquaculture (Fish farming)
• Environmental value (Wetlands, rivers, lakes)

The Global perspective
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Global water use characteristics
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Global water use characteristics cont.
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Global water consumption - total volume
The Global perspective
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Global water consumption - of runoff
The Global perspective
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How much fresh water is available in a
country/region (for example in Egypt)?

• Precipitation
• River inflow
• Regional water import
• Groundwater inflow
• Evaporation
• River outflow
• - Regional water export
• - Groundwater outflow
• Total available m3/year

The total available volume of water is usually
limited and determined by climate and geology.
Some of it may be put to use but rarely utilized
100, with advanced technology and management ?
40-50 NB Groundwater can be a source of water
but it must be included in the balance!
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How much water can we actually use?

• Water use is usually limited by two main
  problems as seen from the user point of view
• The water is not where we want to use it
  (spatial variation)
• The water is not there when we need it (temporal
  variation)
• The spatial problem occurs when major
  consumption sites, for example large cities, are
  located in dry areas, while most of the rainfall
  occurs in unhibited mountainous areas
• The temporal problem occur because rainfall and
  runoff tend to have large seasonal variations
  with long dry seasons and short High flow (flood)
  seasons, while consumption is fairly constant. In
  addition long term variation occur, for example
  of El Nino type or on longer timescales (Sahel,
  Lake Malawi, Zambezi etc)

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Example 1 Spatial variability ?
The water is not where we want to use it
(spatial variation) In Pangani river (below)
precipitation is mainly occurring on the slopes
of Mt Kilimanjaro, Mt Meru, Pare Mountains and
the Ushambara. Here precipitation exceeds 2000
mm/yr, while in most of the catchment the area is
dry (lt 500 mm/yr)
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Example 2 Seasonal variability ?
The water is not there when we want to use it
(temporal variation). In Pangani river (below)
precipitation is mainly occurring during 3-4
months (Feb-May). If water is not stored most of
the runoff occur in the same periode, as seen
from graphs below.
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Solutions to seasonal/long term variability ?
The water is not there when we want to use it
(temporal variation). The solution to this
problem is to build dams. Dams are expensive,
often with possible environmental effects, and
usually controversial. There are, however few
substitutes if a stable water supply is needed,
for example for irrigation, municipal water
supply or hydropower
Storage of snow-melt flow
Professor Ånund Killingtveit
Storage of rainy season flow
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Solutions to spatial variability ?
The water is not where we want to use it
(spatial variation). The solution to this
problem is to build water transfer systems,
canals, tunnels, diverting rivers etc. These
systems are expensive, often with possible
environmental effects, and usually controversial.
There are, however few substitutes if a stable
water supply is needed, for example for
irrigation, municipal water supply or hydropower.
Large regional irrigation canal
Small irrigation canal
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How much water can we use?
Water consumption is usually fairly evenly
distributed Water avaliability typically varies
strongly seasonal ?Need for storage but not all
water can be stored because reservoirs suffer
from evaporation losses
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How much water do we need?

• Water demand depends on
• Climate
• Degree of industrial development
• Agriculture (Irrigation)
• Water technology for storage, transport and use

Typical basic demand is a minimum of 100 l pr.
person and day, or approx. 40 m3/yr In reality a
minimum of 500 m3/yr may be necessary in dry
climate, with irrication the average increases.
Water stress occur when average lt 1700
m3/yr Water shortage when average lt 1000 m3/yr
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Analysis of water demand vs. water availability
Water need per capita (m3 per person per year)
? (log scale)
100
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Increasing mobilization of Water resources
demands better Technology and management
Minimum water need
Limited management problems
Large management problems
Regional management needed
Water availability per capita (m3 per person per
year) ? (log scale)
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Analysis of water demand vs. water availability
Water need per capita (m3 per person per year)
? (log scale)
100
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Professor Ånund Killingtveit
Water availability per capita (m3 per person per
year) ? (log scale)
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Macroscale comparison of water availability vs.
water demand (From Falkenmark)
100
Water need per capita (m3 per person per year)
? (log scale)
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Increasing demand but fixed resources
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Water availability per capita (m3 per person per
year) ? (log scale)
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Water resources are fixed population increases
The Global perspective
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The Global perspective
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Regional overview
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Regional characteristics - Africa
Sum for Africa 4570 km3/year
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Regional characteristics - Africa
Average for Africa 6500 m3/capita/year
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Regional characteristics - Africa
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Regional characteristics - Africa
Available water, 1000 m3/capita/year
Average for Africa 6500 m3/capita/year
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Regional characteristics - Africa
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Regional characteristics - Europa
Water resources at yr. 2000 (m3/capita/year)
Average for Europe 4700 m3/capita/year (Norway
96 000 m3/capita/year)
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Regional characteristics East Asia
Water resources at yr. 2000 (m3/capita/year)
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Regional characteristics West Asia
Water resources at yr. 2000 (m3/capita/year)
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Water use characteristics
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Sustainable water use Renewable water resources
Some important steps UN Water conference in Mar
del Plata (1977) The Brundtland report
(1987) Dublin principles, Water and
Environment(1992) Rio-conference, Agenda 21
(1992) World Water Vision (2000)
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Sustainable water use

• Sustainable development has been defined as
• "development that meets the needs and
  aspirations of the present without compromising
  the ability of future generations to meet their
  own needs" (Brundtland 1987)
• Implicit in the desire for sustainability is the
  moral conviction that the current generation
  should pass on its inheritance of natural wealth,
  not unchanged, but undiminished in potential to
  support future generations.
• A sustainable development should consider a time
  span of many generations.
• Also, natural hydrological variations within this
  time span should be considered

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Renewable and Non-renewable resources

• Renewable resources tend to be flow-limited and
  are reconstituted after human consumption or
  dispersion through natural processes driven by
  solar energy (which may be enhanced by human
  investment, as when trees are planted).
• Example River flow, shallow groundwater,
  biomass
• Nonrenewable resources are generally
  stocklimited and have either very low or no
  renewal rates and prohibitive reconstitution
  costs
• Example Fossil groundwater aquifers, Topsoil,
  Tropical Rainforests, Oil, Natural gas

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Renewable and Non-renewable resources

• Groundwater resources have often very low renewal
  rates and its sustainable use should be limited
  to its infiltration rate (renewable rate)
• In many countries groundwater is used as if it
  was renewable, while in reality the groundwater
  is fossil, the aquifer was filled hundreds or
  thousands years ago

• Examples Libya,
• Saudi-Arabia,
• USA,
• Australia,
• India,
• China,
• ...

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Other water-related problems

• Floods
• Droughts

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Other water-related problems

• Floods account for 1/3 of natural catastrophes
• And more than 50 of lives lost
• Flood losses in 90s was 10 times losses in 60s
• An average of 66 Million people suffered flood
  damage annually in the years from 1973-1997
• Reasons for increased flooding problems are many
• Population trends in exposed regions
• Increase in exposed values
• Construction on flood-prone areas
• Failure of flood protection works
• Changes in environment conditions (e.g.
  Deforestation, Filling of wetlands, Urbanization)
• Climate changes (?)

Floods

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Other water-related problems

• Increased water abstraction from rivers
• Changes in land use (deforestation)
• Long term climatic variability (Sahel, Ethiopia,
  ..)
• Climate change (?)
• Some examples
• Amu Darya and Syr Darya in Central Asia are
  drying up due to increased water use
• The Yellow river in China did not reach the sea
  for 7 months in 1997 vs. A few days in 1972
• The Colorado River in US is drying up
• England had a disastrous drought in the 1980s
• Disasters in Ethiopia and Eritrea
• ...

Droughts

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Non-Sustainable water use Some examples

• The Aral Sea disaster
• The Ogallala Aquifer in USA
• Saudi Arabia ground water irrigation system
• ? All examples related to overexploation of
  resources
• (non-sustainable use of limited water
  resources)

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Non-Sustainable water use Some examples
The Aral Sea
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Non-Sustainable water use The Aral Sea

• 1960
• Annual catch 50000 tons
• 60000 employed in fishing industry
• Aral sea 4th largest in the world

• 2000
• Annual catch 0 tons
• No commercial fishery
• Area reduced by 75

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Non-Sustainable water use The Aral Sea
Most of the changes have occurred within a time
span when remote sensing was operational ...
1976
1997
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Non-Sustainable water use The Aral Sea

• Water has been removed from the Aral Basin by
  the diversion of water from the Amu Darya River
  (which feeds the Aral Sea.)
• Water from the Amu Darya is diverted into the
  Karakum Canal in Turkmenistan, near Afghanistan.
  The Karakum Canal, at 1400 km (850 miles), is
  the world's longest canal.
• Water is used for irrigation in the formery dry
  desert areas where in particular cotton
  production is important
• The destruction of the Aral Sea is the
  consequence of bringing desert soils into
  agricultural production

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Non-Sustainable water use The Aral Sea
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Non-Sustainable water use The Ogallala aquifer
in USA

• The High Plains aquifer, actually a network of
  aquifers in the midwestern United States, covers
  174,000 square miles (450,000 square kilometers)
  from South Dakota to Texas. The system is
  frequently called the Ogallala for the formation
  that dominates it
• Water from this aquifer system helped transform
  the prairies of the plains into one of the
  country's most productive agricultural areas and
  the aquifer network remains the basic water
  source for much of the grain belt from Texas to
  Minnesota. But signs of scarcity and
  contamination have been emerging in recent years.
• Situated in a semi-arid region with little
  rainfall and few perennial streams, the Ogallala
  recharges very slowly.

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Non-Sustainable water use The Ogallala aquifer
in USA

• As farmers use advanced irrigation technology to
  pump water out faster than it can be naturally
  replenished, some are now removing a gallon
  (roughly 4 liters) out for every teacupful
  restored by the natural processes of aquifer
  recharge.
• As a result, water tables are falling, pumping
  costs are escalating, and irrigated lands are
  being pushed out of production.
• Between the 1940s and 1980, the average water
  level in the aquifer dropped almost 10 feet (3
  meters), with declines exceeding 100 feet (30
  meters) in some parts of Texas. By 1990,
  estimates of depletion of the Texas portion of
  the aquifer reached 24 percent--a loss of 164
  billion cubic meters, or the equivalent of almost
  six years of the entire state's water use

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Non-Sustainable water use Groundwater mining
in Saudi-Arabia

• With no rivers and lakes and only 100 millimeters
  of annual rainfall Saudi Arabia has come to rely
  on the unsustainable mining of one of its less
  well known natural resources groundwater.
• Ninety percent of the water Saudi Arabia uses
  comes from underground reserves, virtually all of
  which were filled thousands of years ago and have
  negligible annual recharge today.
• In 1992, the government spent more than 2
  billion in subsidies for the domestic production
  of four million tons of wheat, which could have
  been purchased on the world market for a fifth of
  that price.

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Non-Sustainable water use Groundwater mining
in Saudi-Arabia

• Estimates of the lifespan for Saudi fossil water
  reserves vary widely, with one estimate
  suggesting they could run out early in this
  century.
• The country's population of 17.5 million is
  projected to climb past 40 million by 2025, by
  which time groundwater mining may no longer be a
  realistic option.
• Food self-sufficiency may be a priority in the
  short-term, but it cannot be sustained
  indefinitely with non-renewable water.

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Summary

• Global freshwater consumption rose sixfold
  between 1900 and 1995 - at more than twice the
  rate of population growth
• About one-third of the world's population already
  lives in countries with moderate to high water
  stress - that is, where water consumption is more
  than 10 per cent of the renewable freshwater
  supply
• The problems are most acute in Africa and West
  Asia but lack of water is already a major
  constraint to industrial and socio-economic
  growth in many other areas, including China,
  India and Indonesia
• In Africa, 14 countries are already subject to
  water stress or water scarcity, and a further 11
  countries will join them in the next 25 years

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Summary cont.

• If present consumption patterns continue, two out
  of every three persons on Earth will live in
  water-stressed conditions by the year 2025 (WMO
  and others 1997).
• The declining state of the world's freshwater
  resources, in terms of quantity and quality, may
  prove to be the dominant issue on the environment
  and development agenda of the coming century.
• Worldwide, agriculture accounts for more than 70
  per cent of freshwater consumption, mainly for
  irrigation of agricultural crops. In Africa and
  Asia, agriculture accounts for nearly 80 per
  cent.
• Agricultural demand for water is projected to
  increase sharply, since much of the additional
  food that will be needed to feed the world
  population in the future is expected to come from
  an increase in irrigated land.

Professor Ånund Killingtveit