Quantifying waterlogging effects on crop production at different spatial scales

The increasing number of extreme rainfall events across Europe is making waterlogging a threat to agricultural production. Prolonged soil saturation blocks the oxygen supply to roots, hindering crop growth and development. Waterlogging emerges in heterogeneous spatiotemporal patterns, which makes it difficult to quantify the resulting yield penalty. This study aims to detect waterlogging at the sub-field scale with the help of remote sensing, and to quantify associated yield losses using a process-based crop model. Waterlogging was detected using a Sentinel-1 SAR-based classification framework combining Edge–Otsu thresholding and Log-cumulant Gamma Markov Random Field (LGM) at the field scale, while Sentinel-2 derived vegetation indices were used to assess vegetation responses associated with waterlogged areas. A process-based crop model (MONICA), including a topography-based precipitation modulator, was applied to simulate waterlogging conditions leading to oxygen stress, and to quantify associated yield reductions. Analyses were conducted at both regional and field scales, with biomass reductions assessed for major winter crops and process-based yield reductions simulated for winter wheat. Regional-scale analysis revealed that crops in waterlogged areas exhibited vegetation indices 42% (triticale) to 61% (oilseed rape) lower than in non-waterlogged areas, particularly during the early growth stages. Results of the MONICA model showed a mean yield decreases of 22.6% for winter wheat in an example field under waterlogging conditions. Both remotely sensed waterlogging patterns and simulated oxygen stress consistently highlighted topographic depressions as hotspots of waterlogging impact. Incorporating a topography-based precipitation modulator into process-based MONICA simulations resulted in a strong spatial correspondence between simulated yield losses and satellite-derived biomass reductions, thereby emphasizing the importance of terrain in controlling water accumulation and waterlogging impacts.