IrrEM (Irrigation in the eastern Mediterranean): Two and a half decades of seasonal high-resolution irrigated land maps of the eastern Mediterranean

Abstract. Irrigation supports food security, drought resilience, and economic growth, but strains water resources and the environment. The eastern Mediterranean is a water-stressed region that relies heavily on agriculture. However, long-term irrigation patterns and their response to the regional challenges, such as frequent droughts and a war-torn agricultural system, remain poorly studied. NASA’s satellite archive and recent remote sensing advancements offer an opportunity to fill this gap and support informed decision-making; however, adapting these tools to data-scarce regions and varying conditions remains a challenge. In this study, we present IrrEM (Irrigation in the eastern Mediterranean), which leverages the long-standing Landsat archive, a technique less reliant on training data, and cloud computing to map summer and winter irrigation extent at 30-m spatial resolution for the last 26 years in the eastern Mediterranean. We first processed each Landsat image into relative soil moisture using the Optical Trapezoid Model (OPTRAM). Next, we derived spatial and temporal irrigation indicators by tracking irrigation-induced changes of relative soil moisture across time and space, then used them to delineate irrigation extent. Evaluated against independent reference data, the maps achieved F-scores—the harmonic mean of precision and recall— ranging from 0.67 to 0.85. The open-access release comprises the annual summer and winter irrigation maps, ancillary layers (per-season counts of valid satellite observations and detected irrigation events), the OPTRAM parameters, the labelled reference data, the processing code, and an interactive web viewer (DOI: https://doi.org/10.5281/zenodo.17574601). Our study provides reproducible, timely, long-term, high-resolution irrigation maps for the eastern Mediterranean, freely available to support informed decisions, policy design, international aid, and further research in climate, agronomy, hydrology, and human-environment interaction.