Time Series Analysis of Evapotranspiration for Assessing Drough Impact on Wheat Yield

Drought is a devastating natural hazard which causes reductions in crop yields. This study aims to analyze the relationship between wheat yield and evapotranspiration (ET) dynamics across the last two decades in the Iberian Peninsula. A two-source energy balance (TSEB) model with Terra/Aqua MODIS data and the ERA5 atmospheric reanalysis dataset were used to calculate daily ET at 1 km spatial resolution. The Breaks for Additive Seasonal and Trend (BFAST) method was applied to detect drought events. The ET time series was decomposed into seasonal, trend, and remainder components using BFAST to identify changes in trend and seasonal components in the 22-year daily ET time series. Breakpoints were identified in the ET time series corresponding to the years of yield decline. Results showed ET anomalies can serve as an indicator for recognizing droughts. This research suggests the utility of time series analysis of ET for early drought detection, a practical approach for mitigating the impact of climatic change on crop yields.