Enhancing AquaCrop-OSPy yield predictions with UAV-based remote sensing data: a case study on broccoli

Abstract

Efficient irrigation of horticultural crops under increasing water scarcity requires crop models that exploit high–resolution remote–sensing (RS) data. This study evaluated how unmanned aerial vehicle (UAV) multispectral and thermal observations improved AquaCrop-OSPy simulations of canopy cover (CC), actual evapotranspiration (ETₐ) and yield for irrigated broccoli under Mediterranean conditions. Broccoli was grown for two seasons in a 0.2 ha field in eastern Spain under two irrigation strategies: decision–support Irrigation Advisor (IA) versus farmer practice. A global sensitivity analysis (GSA) and two–stage calibration against Season 1 CC and yield identified canopy growth (CGC), harvest index (HIₒ) and transpiration phenology (GDDᵤₚ) as dominant controls; the calibrated model was validated in Season 2. UAV imagery provided CC via supervised classification and ETₐ via a two–source energy balance model (pyTSEB), which were assimilated into AquaCrop-OSPy on three dates using a hybrid observed–simulated scheme. Compared with lysimeter measurements, pyTSEB reproduced ETₐ with root–mean–square error (RMSE) 0.39 mm d⁻¹ and Nash–Sutcliffe efficiency (NSE) 0.93, whereas baseline AquaCrop-OSPy showed RMSE 1.24 mm d⁻¹ and NSE 0.27. Without assimilation, AquaCrop-OSPy reproduced mean yield but not subplot variability (RMSE 1.67 t ha⁻¹). Assimilating CC reduced yield RMSE by 8.9 %, ETₐ alone gave smaller gains, and joint CC + ETₐ assimilation achieved the lowest RMSE (1.47 t ha⁻¹, 11.9 % reduction). Across seasons, IA applied 20.6 % more water than farmer practice with no consistent yield or water–productivity benefits. These results, obtained within the limitations of this study, indicate that UAV-derived CC, complemented by ETₐ, modestly improves AquaCrop-OSPy yield predictions. Nevertheless, they should be interpreted as indicative rather than definitive and motivate further evaluations.

Code and data availability

公開状態または取得可能な本文経路を確認できませんでした。

No evidence-backed public reproduction asset is currently recorded.