Irrigation water requirement (CLIM 033) - Assessment published Jul 2014
Climate change (Primary topic)
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
- CLIM 033
Key policy question: How is climate change affecting the water requirement of agricultural crops and water availability for irrigation across Europe?
- Model-based estimates suggest that the volume of water required for irrigation during the period from 1975 to 2010 has increased in the Iberian Peninsula and Italy whereas it has decreased in parts of south-eastern Europe.
- For high emissions scenarios, increases in irrigation demand of more than 25% during the 21st century are projected for most irrigated regions in Europe.
- The impact of increasing water requirements is expected to be most acute in southern Europe, where the suitability for rain-fed agriculture is projected to decrease and irrigation requirements are projected to increase most.
Rate of change of the meteorological water balance
Note: This figure shows the rate of change of the ‘water balance’. The map provides an estimate increase (red in map) or decrease (blue in map) of the volume of water required from irrigation assuming that all other factors are unchanged and given that there is an irrigation demand.
- Rate of change of frost-free period map for Europe provided by Geo network - open source
Projected change in water availability for irrigation in the Mediterranean region
Note: This figure shows the relative change in water availability for irrigation as projected under the A1B emission scenario by the HIRHAM (DMI) regional climate model for 2071-2100 relative to 1961-1990. Light yellow areas indicate no change in water availability.
- Regional Assessment of Climate Change in the Mediterranean provided by Euro-Mediterranean Centre on Climate Change (CMMC)
Irrigation in Europe is currently concentrated along the Mediterranean where some countries use more than 80 % of total freshwater abstraction for agricultural purposes[i]. However, consistent observations of water demand and consumption for agriculture do not currently exist for Europe, partly due to unrecorded water abstractions and to national differences in accounting and reporting. Modelling approaches can be used to compute net irrigation requirements. Two studies estimated net irrigation requirements in Europe for 1995-2002 and for the year 2000 with a total of three different model systems[ii]. The results show an irrigation requirement of up to 21-40 km3 for Spain, which has the highest net irrigation requirement in the EU27. Net irrigation requirements per area in Europe generally increase from North to South, determined by climatic conditions, soil properties and crop composition.
Past trends in water demand can be estimated on the basis of meteorological data. Figure 1 shows the change in the water balance, which is the difference between rainfall and modelled reference evapotranspiration, which is not crop-specific. This indicator provides a rough proxy for changes in actual irrigation demand, which is determined also by local soil conditions, the crops grown, and the type of irrigation applied. In the period considered (1975–2010), both the Iberian Peninsula and Italy have experienced an increase in the volume of water required for irrigation if yields of irrigated crops were to be maintained, whereas parts of south-eastern Europe have experienced a decrease.
A recent multi-model study using seven global hydrological models driven by five global climate models under four representative concentration pathways (RCPs) estimated changes in irrigation water demand (IWD) across regions during the 21st century. Under the low and low-medium emissions scenarios RCP2.6 and RCP4.5, simulated changes in IWD across Europe are small. For RCP6.0, the multi-model average suggests a substantial increase in IWD in most of Europe. For RCP8.5, the projected increase in IWD exceeds 25% in most of the irrigated regions in Europe[iii]. Most hydrological models in this multi-model study did not consider the physiological effect of increased CO2, which can increase the water use efficiency of crop plants. The only available study using a hydrological and crop model that considers the physiological effect of increased CO2 still estimates that IWD in southern Europe increases by more than 20% until 2080 with a high likelihood[iv]. Regional case studies suggest much higher increases in IWD in some regions[v].
Changes in climate and CO2 are not the only factors affecting future IWD. Other important factors include changes in population, dietary preferences and food demand, land-use change and water-use policies. An integrated analysis of two socio-economic scenarios and one climate scenario (SRES A2) for pan-Europe showed almost no changes in IWD under a sustainability-oriented socio-economic scenario, whereas the combination of climate change with a market-oriented scenario lead to an increase in IWD of 45% [vi].
Climate change will also affect water availability. The Mediterranean area is projected to experience a decline in water availability, and future irrigation will be constrained by reduced runoff and groundwater resources, demand from other sectors, and by economic costs[vii]. Assuming that urban water demands would have preference over agricultural purposes, the proportional reduction of water availability for irrigation in many European basins is larger than the reduction in annual run-off (Figure 2)[viii].
Adaptation measures and integrated management of water, also across countries’ boundaries, are needed to address future competing demands for water between agriculture, energy, conservation and human settlements. New irrigation infrastructure will be required in some regions[ix].
[i] EEA,Water Resources across Europe — Confronting Water Scarcity and Drought, EEA Report (Copenhagen: European Environment Agency, 2009), http://www.eea.europa.eu/publications/water-resources-across-europe.
[ii] Gunter Wriedt et al., ‘Estimating Irrigation Water Requirements in Europe’,Journal of Hydrology 373, no. 3–4 (15 July 2009): 527–44, doi:10.1016/j.jhydrol.2009.05.018; T. aus der Beek et al., ‘Modelling Historical and Current Irrigation Water Demand on the Continental Scale: Europe’,Adv. Geosci. 27 (7 September 2010): 79–85, doi:10.5194/adgeo-27-79-2010.
[iii] Yoshihide Wada et al., ‘Multimodel Projections and Uncertainties of Irrigation Water Demand under Climate Change’,Geophysical Research Letters 40, no. 17 (16 September 2013): 4626–32, doi:10.1002/grl.50686.
[iv] Markus Konzmann, Dieter Gerten, and Jens Heinke, ‘Climate Impacts on Global Irrigation Requirements under 19 GCMs, Simulated with a Vegetation and Hydrology Model’,Hydrological Sciences Journal 58, no. 1 (2013): 88–105, doi:10.1080/02626667.2013.746495.
[v] R. Savé et al., ‘Potential Changes in Irrigation Requirements and Phenology of Maize, Apple Trees and Alfalfa under Global Change Conditions in Fluvià Watershed during XXIst Century: Results from a Modeling Approximation to Watershed-Level Water Balance’,Agricultural Water Management 114 (November 2012): 78–87, doi:10.1016/j.agwat.2012.07.006.
[vi] Rüdiger Schaldach et al., ‘Current and Future Irrigation Water Requirements in Pan-Europe: An Integrated Analysis of Socio-Economic and Climate Scenarios’,Global and Planetary Change 94–95 (August 2012): 33–45, doi:10.1016/j.gloplacha.2012.06.004.
[vii] J.E. Olesen et al., ‘Impacts and Adaptation of European Crop Production Systems to Climate Change’,European Journal of Agronomy 34, no. 2 (February 2011): 96–112, doi:10.1016/j.eja.2010.11.003.
[viii] Ana Iglesias et al., ‘Water and People: Assessing Policy Priorities for Climate Change Adaptation in the Mediterranean’, inRegional Assessment of Climate Change in the Mediterranean, ed. Antonio Navarra and Laurence Tubiana, Advances in Global Change Research 51 (Springer Netherlands, 2013), 201–33, http://link.springer.com/chapter/10.1007/978-94-007-5772-1_11.
[ix] Marijn van der Velde, Gunter Wriedt, and Fayçal Bouraoui, ‘Estimating Irrigation Use and Effects on Maize Yield during the 2003 Heatwave in France’,Agriculture, Ecosystems & Environment 135, no. 1–2 (1 January 2010): 90–97, doi:10.1016/j.agee.2009.08.017.
Regional Assessment of Climate Change in the Mediterranean
provided by Euro-Mediterranean Centre on Climate Change (CMMC)
Monitoring Agricultural ResourceS (MARS)
provided by Joint Research Centre (JRC)
More information about this indicator
See this indicator specification for more details.