Droogte in overvloed

Transcriptie

1 Droogte in overvloed Erik Querner m.m.v. Henny van Lanen (WU) Inhoud Inleiding Intermezzo s: waterbeheer en droogte Historische droogte Monitoring Droogte voorspellen Evrotas, Griekenland Mendoza, Argentinië Discussie

2 Inleiding Een droogte is een langere periode van maanden of jaren, waarin een regio een tekort in de watervoorziening heeft. In het algemeen een tekort in neerslag, maar ook sneeuwval in de bergen of rivierafvoer uit de bergen. Vele delen van de wereld komt droogte elk jaar voor, met name als er een lange droge zomer is en daarnaast ook een natte periode. Droogte (natuurlijk) niet verwarren met waterschaarste (een door de mens veroorzaakt tekort) Consequences of a drought Environmental, agricultural, health, economic and social Diminished crop growth or yield productions Dust storms, bush fires Hunger due to lack of water for irrigation Habitat damage, affecting both terrestrial and aquatic wildlife Reduced electricity production due to insufficient available coolant for power stations, and reduced water flow through hydroelectric dams Reduce the water quality in streams (reduce dilution of pollutants) Shortages of water for industrial users

3 Types of droughts Human influence

4 Klimaatclassificatie van Köppen Geiger Classification is based on the concept that native vegetation is the best expression of climate. It combines average annual and monthly temperatures and precipitation, and the seasonality of precipitation.

5 Droogte indicatoren Percentage of Normal Precipitation actual divided by the normal Standardized Precipitation Index (SPI) probability index Palmer Drought Severity Index a soil moisture algorithm Crop Moisture Index Surface Water Supply Index calculated by river basin, based on snowpack, stream flow, precipitation, and reservoir storage. Reclamation Drought Index calculated at the river basin level, incorporating temperature, precipitation, snowpack, stream flow, and reservoir levels as input. Historische droogte In 1389 stond de Rijn bij Keulen voor de derde keer in tien jaar zo laag dat de paarden midden in de rivier liepen Zomer 1473 van eind april tot half november nauwelijks regen 1503: zeker vier maanden lang viel er nauwelijks regen 1540: Het grote zonnejaar 7 maanden droog en heet De Rijn stond vrijwel droog. Het midden en westen van Europa hadden een Mediterraan klimaat. In Parijs liepen mensen over de bedding van de Seine zonder natte voeten te krijgen. De 19e eeuw kende een paar opmerkelijk droge jaren: zo viel in Maastricht in 1857 slechts 356 millimeter en in 1864 werd daar 363 millimeter gemeten.

6 Amerika, mid westen: The Dust Bowl The Dirty Thirties was a period of severe dust storms causing major ecological and agricultural damage in America and Canada. The phenomenon was caused by severe drought coupled with decades of extensive farming without care to prevent erosion. The Dust Bowl affected 400,000 km 2, mainly in Texas, Oklahoma, and adjacent parts of New Mexico, Colorado, and Kansas. Dust storms were given names as "Black Blizzards" and "Black Rollers"

7 High planes Aquifer Its one of the world's largest aquifers, it covers an area of approximately 450,000 km² in eight states of the US. About 27% of the irrigated land in the United States overlies this aquifer system, which yields about 30 percent of the nation's ground water used for irrigation. In addition, the aquifer system provides drinking water to 82 percent of the people who live within the aquifer boundary. Some estimates say it will dry up in about years. Dad where is our water gone to Son I tell you when your grown up

8 Evrotas basin, Greece Water use in a river basin Irrigation Agriculture Drainage Groundwater extractions Rainfed agriculture Regions prone to droughts often have a high water use Intensive Agriculture Urban areas - Industries (etc.) Example case study MIRAGE Mediterranean Intermittent River ManAGEment Case study sites

9 Ecological Status Aquatic communities structure Sediment & surface water quality Aquatic & terrestrial linkages Functional attributes (nutrient retention, organic matter processing, sediment transport) Basic Research Develoment of measures and support of RBMP Specifications for WFD application in dry streams Supporting the WFD Implementation for temporary streams Hydrological Status Stream temporality Sensitivity to climate change Runoff generation Flood risk Sustainable use of the water resources in Mediterranean river basins for agriculture, drinking water and industries What is sustainable limit to the irrigation in a river basin Temporary Rivers are part of the Prat, year dry 2009 Linking hydrology to ecology

10 Evrotas River basin, Greece Catchment: 2420 km 2 Elevation: m Precipitation: 870 mm Evapotranspiration: 811 mm Geology: Karst and sediments Characteristics of the Evrotas basin Population: Natural vegetation: 61% Agricultural areas: 38% Urban areas: 1% Point Pollution Land uses Untreated domestic waste water Olive oil mills, orange juice factories Diffuse Pollution of nutrients and pesticides

11 Hydrological pressures Irrigation: Surface water abstraction for irrigation Ground water abstractions (3.500 wells Drinking water and industrial use Groundwater abstractions Surface water used for irrigation

12 Decline in river flow Discharge m 3 /s Spring Summer Autumn

13 Water balance study using SIMGRO model Example scenarios 1900: only surface water used for irrigation (agric. 25%) 1960: surf water and shallow groundwater (agric. 25%) 1980: surf water and deep groundwater (agric. 30%) Discharge (m3/s) Present: agricultural land 38% (olives irrigated) Discharges at Vrontamas - Evrotas Present Measurements 0 02/01/05 02/07/05 02/01/06 02/07/06 02/01/07 02/07/07 02/01/08

14 Flow characterization Dry; pools; low flows; flowing Visualize changes for different irrigation intensities Determine what is acceptable/sustainable from an ecological point of view It then defines the max water use for irrigation Preliminary conclusion: for a sustainable situation at river basin level, the water use for agriculture needs (definitely) to be reduced

15 Recent droughts Droughts largest impact of all natural disasters (climatic and geological) China Feb Mar 2010

16 Russia Jun Jul 2010 De Rijn Mei 2011 Rijn: 10 mei m 3 /s

17 Rijn bij laag water Mendoza, Argentinie

18 Mendoza province has more than 20% of the irrigated land in Argentina Irrigation water is allocated according to area with water rights Problems water shortage (dry years) suppl. groundwater use over irrigation (wet years) high water tables soil salinization crop productivity reduction environmental degradation MENDOZA RIVER BASIN Andes Saline soils Potrerillos dam Mendoza city Mendoza irrigated system Mendoza river

19 Diversion dam in Mendoza River Before and after construction of dam

20 Irrigation canals Crops: grapes; fruit trees; olives, vegetables

21 Used to grow good quality wines Recente ontwikkelingen Als er geen oppervlaktewater beschikbaar is, dan maar grondwater gebruiken, zoals deze Nederlandse wijnboer

22 en deze Nederlandse aardappelboer Grondwaterstandsdaling door 7 pompen (ca. 5 mln m 3 beregening nov maart) 30 m

23 Water resources are used for 100% or even more Droogte in Overvloed Monitoring

24 European Drought Observatory European Drought Observatory Evolution of the 3 month Standardized Precipitation Index (SPI 3) over western Europe from Jan April Values below 1.5 indicate a severe meteorological drought.

25 Africa La Nina threatens 2 million Ethiopians with drought Thu Apr 28, 2011 ADDIS ABABA More than two million Ethiopians are in need of food aid due to drought caused by one of the worst La Nina weather phenomenon in a decade, the United Nations said. La Nina, which was blamed for Australia's floods this year, is an abnormal cooling of waters in the Pacific Ocean that wreaks havoc with weather patterns across the Asia Pacific region, and has brought poor rains to the Horn of Africa.

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27 Droogte in Overvloed Voorspellingen Trend in droughts Palmer Drought Severity Index for 1900 to 2002 Cumulative deficit in precipitation and evapotranspiration

28 IPCC 100 years ahead Expected droughts in Europe Change in the recurrence of 100 year droughts, based on comparisons between climate and water use in 1961 to 1990 and simulations for the 2070s (based on the ECHAM4 and HadCM3 GCMs, the IS92a emissions scenario and a business as usual water use scenario). (Lehner et al., 2005)

29 Discussie Droogte is een sluimerend proces Door toenemende bevolking en ontwikkelingen in de landbouw komt droogte steeds vaker en heviger voor Er is een noodzaak om water besparende maatregelen en technieken in de landbouw toe te passen Grondwater wordt algemeen gezien als een oneindige bron, maar in veel gebieden wordt nu ingeteerd op de reserves Noodzaak tot risico spreiding Meer water vasthouden om droge perioden te overbruggen

30 Risico spreiding very innovative high production unit (similar to a Greenhouse) Multiple use wetland higher production and drought resistant fields traditional extensive fields Thank you