Climate-driven interannual variability in subnational irrigation areas across Europe - Article in Communications Earth & Environment
03 October 2024: In an article published today in the journal Communications Earth & Environment, Wanxue Zhu and Stefan Siebert have analyzed how the sequence of dry and wet years affects the extent of irrigated land in Europe. While it is clear that in dry years the irrigation water demand per hectare of irrigated area is higher than in wet years, there is little information on whether the irrigated area is also larger and if so, how much. For most regions in Europe there is also no data on this, as statistics on irrigated area are only collected in the agricultural structure surveys, which are carried out every 3-4 years. Due to the lack of data, most large-scale models therefore use static land use or at best depict long-term trends in the irrigated area, but not the variability between years. This can result in an underestimation of irrigation water requirements in dry years.
In the current study, the GCWM model was used to calculate the irrigation requirements in Europe for 26 crops in the period 1990-2020 in high resolution with static land use and a drought indicator was derived from this. Then, using the available data for the European NUTS2 regions, it was checked whether the fraction of the area with irrigation infrastructure that was actually irrigated in the individual years correlates with the drought indicator. The relationship derived for each NUTS region between the drought indicator and the proportion of irrigated area was then used to estimate irrigated area as a function of drought status in order to fill the data gaps in the time series across Europe.
It was found that in most regions, drought status and irrigated area are positively correlated, i.e. the irrigated area is larger in dry years. However, there are also countries, such as Spain, where the irrigated area is lower in dry years, which could be due to restrictions in the irrigation water supply. In the analyzed period 1990-2020, the total irrigated area in Europe was largest in the dry year 2018 and lowest in the wet years 2002 and 2014 (see figure). The impact of this variability in irrigated areas on irrigation water use and regional climate is still subject of current research in the Collaborative Research Center DETECT.
Anomalies in irrigated area (left) and drought status (right) in 2014 (top) and 2018 (bottom). A negative anomaly means less irrigated area, positive anomalies mean more irrigated area. In most regions of Europe, the irrigated area is larger in dry years (brown coloured) than in wet years (green coloured).
Further information:
Contact person(s) in Division Agronomy:
- Prof. Dr. Stefan Siebert, Tel. 0551-39-24359, stefan.siebert@uni-goettingen.de
- Wanxue Zhu, Tel. 0551-39-24361, wanxue.zhu@agr.uni-goettingen.de