Net irrigation requirement under different climate scenarios using AquaCrop over Europe

Abstract

Abstract. Global soil water availability is challenged by the effects of climate change and a growing population. On average, 70 % of freshwater extraction is attributed to agriculture, and the demand is increasing. In this study, the effects of climate change on the evolution of the irrigation water requirement to sustain current crop productivity are assessed by using the Food and Agriculture Organization (FAO) crop growth model AquaCrop version 6.1. The model is run at 0.5∘lat×0.5∘long resolution over the European mainland, assuming a general C3-type of crop, and forced by climate input data from the Inter-Sectoral Impact Model Intercomparison Project phase three (ISIMIP3). First, the AquaCrop surface soil moisture (SSM) forced with two types of ISIMIP3 historical meteorological datasets is evaluated with satellite-based SSM estimates in two ways. When driven by ISIMIP3a reanalysis meteorology, daily simulated SSM values have an unbiased root mean square difference of 0.08 and 0.06 m3 m−3, with SSM retrievals from the Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) missions, respectively, for the years 2015–2016 (2016 is the end year of the reanalysis data). When forced with ISIMIP3b meteorology from five global climate models (GCMs) for the years 2015–2020, the historical simulated SSM climatology closely agrees with the satellite-based SSM climatologies. Second, the evaluated AquaCrop model is run to quantify the future irrigation requirement, for an ensemble of five GCMs and three different emission scenarios. The simulated net irrigation requirement (Inet) of the three summer months for a near and far future climate period (2031–2060 and 2071–2100) is compared to the baseline period of 1985–2014 to assess changes in the mean and interannual variability of the irrigation demand. Averaged over the continent and the model ensemble, the far future Inet is expected to increase by 22 mm per month (+30 %) under a high-emission scenario Shared Socioeconomic Pathway (SSP) 3–7.0. Central and southern Europe are the most impacted, with larger Inet increases. The interannual variability in Inet is likely to increase in northern and central Europe, whereas the variability is expected to decrease in southern regions. Under a high mitigation scenario (SSP1–2.6), the increase in Inet will stabilize at around 13 mm per month towards the end of the century, and interannual variability will still increase but to a smaller extent. The results emphasize a large uncertainty in the Inet projected by various GCMs.

Irrigation Timing Retrieval at the Plot Scale Using Surface Soil Moisture Derived from Sentinel Time Series in Europe

“…Irrigation water use is a critical factor in managing and optimizing agricultural water resources amid the increasing global demand for irrigation water [1]. The rise in demand is particularly noticeable in response to the production of bioenergy [2], while the decrease in groundwater availability amplifies competition with other sectors, including urban water demand [3].…”

Assessing Net Irrigation Needs in Maize–Wheat Rotation Farmlands on the North China Plain: Implications for Future Climate Scenarios

“…With the exception of the aforementioned se ing of the AquaCrop model simulation, two major assumptions were made to decrease the uncertainty. The first is that the irrigated region was assumed to be unchanged, which can avoid the need to estimate the future hypothetical land use and the uncertainty of the extent of irrigated areas [68,69]; the other is that constant dates of the start and end of the growing season were used, because a dynamic growing season may decrease the comparability of future and baseline irrigation [42].…”

“…Another limitation of previous studies is the lack of consideration of actual water requirements over different crop growth stages. For instance, Busschaert [42] considered that the actual irrigation requirement should be equal to evapotranspiration, whereas others used a fixed threshold value to determine the irrigation amount during the entire growth period [43,44]. To this end, the objective of this study is to investigate irrigation requirements to maintain production over the semi-arid NCP region under future climate projections with high spatial resolution using a well-defined crop model.…”

Water footprints and crop water use of 175 individual crops for 1990–2019 simulated with a global crop model

“…The above-mentioned uncertainties can be reduced by utilising crop yield and CWU estimates from an ensemble of crop models 71,72 , but such endeavour would make global assessments impractical due to large computational requirements. Additionally, the uncertainties can be further minimized by coupling crop models with remote sensing products [73][74][75] . Such an approach is still in the early development stage but could be implemented in future updates of WF datasets.…”