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Globale og regionale perspektiver for tilgjengelighet, behov og utnytting av vannressurser eller ”Global and regional perspectives on availability, demand.

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Presentation on theme: "Globale og regionale perspektiver for tilgjengelighet, behov og utnytting av vannressurser eller ”Global and regional perspectives on availability, demand."— Presentation transcript:

1 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

2 Professor Ånund Killingtveit 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

3 Professor Ånund Killingtveit 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

4 Professor Ånund Killingtveit Flows of the global water cycle (km 3 /yr) (data from Shiklomanov (1992) & WRI (1998)) The Global perspective

5 Professor Ånund Killingtveit Flows of the global water cycle (km 3 /yr) (data from Shiklomanov (1992) & WRI (1998)) The Global perspective

6 Professor Ånund Killingtveit Useful flows of the global water cycle (km 3 /yr) (data from Shiklomanov (1992) & WRI (1998)) The Global perspective

7 Professor Ånund Killingtveit The uneven distribution – the main problem The Global perspective 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)

8 Professor Ånund Killingtveit The Global perspective Global runoff distribution, specific runoff

9 Professor Ånund Killingtveit The Global perspective Global runoff distribution, total volume

10 Professor Ånund Killingtveit The Global perspective Global runoff distribution, pr. capita

11 Professor Ånund Killingtveit The Global perspective 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)

12 Professor Ånund Killingtveit Global water use characteristics

13 Professor Ånund Killingtveit Global water use characteristics cont.

14 Professor Ånund Killingtveit The Global perspective Global water consumption - total volume

15 Professor Ånund Killingtveit The Global perspective Global water consumption - % of runoff

16 Professor Ånund Killingtveit 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 m 3 /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!

17 Professor Ånund Killingtveit How much water can we actually use? Water use is usually limited by two main ”problems” as seen from the user point of view: 1)The water is not where we want to use it (”spatial” variation) 2)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)

18 Professor Ånund Killingtveit 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 (< 500 mm/yr)

19 Professor Ånund Killingtveit 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.

20 Professor Ånund Killingtveit 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 Storage of rainy season flow

21 Professor Ånund Killingtveit 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. Small irrigation canal Large regional irrigation canal

22 Professor Ånund Killingtveit 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

23 Professor Ånund Killingtveit 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 m 3 /yr In reality a minimum of 500 m 3 /yr may be necessary in dry climate, with irrication the average increases. Water stress occur when average < 1700 m 3 /yr Water shortage when average < 1000 m 3 /yr

24 Professor Ånund Killingtveit Analysis of water demand vs. water availability Water availability per capita (m3 per person per year)  (log scale) Water need per capita (m3 per person per year)  (log scale) 10% 20% 100% Minimum water need Increasing mobilization of Water resources demands better Technology and management Limited management problems Regional management needed Large management problems

25 Professor Ånund Killingtveit Analysis of water demand vs. water availability Water availability per capita (m3 per person per year)  (log scale) Water need per capita (m3 per person per year)  (log scale) 10% 20% 100%

26 Professor Ånund Killingtveit Macroscale comparison of water availability vs. water demand (From Falkenmark) 100% 5% 20% Increasing demand but fixed resources Water availability per capita (m3 per person per year)  (log scale) Water need per capita (m3 per person per year)  (log scale)

27 Professor Ånund Killingtveit Water resources are fixed – population increases The Global perspective

28 Professor Ånund Killingtveit The Global perspective

29 Professor Ånund Killingtveit Regional overview

30 Professor Ånund Killingtveit Regional characteristics - Africa Sum for Africa: 4570 km 3 /year

31 Professor Ånund Killingtveit Regional characteristics - Africa Average for Africa: 6500 m 3 /capita/year

32 Professor Ånund Killingtveit Regional characteristics - Africa

33 Professor Ånund Killingtveit Regional characteristics - Africa Available water, 1000 m 3 /capita/year Average for Africa: 6500 m 3 /capita/year

34 Professor Ånund Killingtveit Regional characteristics - Africa

35 Professor Ånund Killingtveit Regional characteristics - Europa Water resources at yr. 2000 (m 3 /capita/year) Average for Europe: 4700 m 3 /capita/year (Norway: 96 000 m 3 /capita/year)

36 Professor Ånund Killingtveit Regional characteristics – East Asia Water resources at yr. 2000 (m 3 /capita/year)

37 Professor Ånund Killingtveit Regional characteristics – West Asia Water resources at yr. 2000 (m 3 /capita/year)

38 Professor Ånund Killingtveit Water use characteristics

39 Professor Ånund Killingtveit 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)

40 Professor Ånund Killingtveit 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

41 Professor Ånund Killingtveit 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

42 Professor Ånund Killingtveit 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,...

43 Professor Ånund Killingtveit Other water-related problems  Floods  Droughts

44 Professor Ånund Killingtveit Other water-related problems  Floods account for 1/3 of natural catastrophes  And more than 50% of lives lost  Flood losses in 90’s was 10 times losses in 60’s  An average of 66 Million people suffered flood damage annually in the years from 1973-1997  Reasons for increased flooding problems are many: 1.Population trends in exposed regions 2.Increase in exposed values 3.Construction on flood-prone areas 4.Failure of flood protection works 5.Changes in environment conditions (e.g. Deforestation, Filling of wetlands, Urbanization) 6.Climate changes (?) Floods

45 Professor Ånund Killingtveit Other water-related problems  Increased water abstraction from rivers  Changes in land use (deforestation)  Long term climatic variability (Sahel, Ethiopia,..)  Climate change (?)  Some examples: 1.Amu Darya and Syr Darya in Central Asia are drying up due to increased water use 2.The Yellow river in China did not reach the sea for 7 months in 1997 vs. A few days in 1972 3.The Colorado River in US is drying up 4.England had a disastrous drought in the 1980’s 5.Disasters in Ethiopia and Eritrea 6.... Droughts

46 Professor Ånund Killingtveit 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)

47 Professor Ånund Killingtveit Non-Sustainable water use – Some examples The Aral Sea

48 Professor Ånund Killingtveit Non-Sustainable water use – The Aral Sea 1960: - Annual catch 50000 tons - 60000 employed in fishing industry - Aral sea 4 th largest in the world 2000: - Annual catch 0 tons - No commercial fishery - Area reduced by 75%

49 Professor Ånund Killingtveit Non-Sustainable water use – The Aral Sea 19761997 Most of the changes have occurred within a time span when remote sensing was operational...

50 - 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 Professor Ånund Killingtveit Non-Sustainable water use – The Aral Sea

51 Professor Ånund Killingtveit Non-Sustainable water use – The Aral Sea

52 Professor Ånund Killingtveit 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.

53 Professor Ånund Killingtveit 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

54 Professor Ånund Killingtveit 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.

55 Professor Ånund Killingtveit 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.

56 Professor Ånund Killingtveit 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

57 Professor Ånund Killingtveit 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.


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