Using NDWI for Diagnosing Moisture Availability in Agricultural Areas Surveyed with UAV

Abstract The study investigates the feasibility of monitoring water content in the topsoil. The study was conducted over five growing seasons from 2019 to 2024. The primary instrument used was an unmanned aerial vehicle (UAV) equipped with a multispectral camera recording reflectance in the near-infrared (NIR) region. Data was collected by flying the UAV at an altitude of 100 m above agricultural areas to capture individual images. These images were then processed to create an orthomosaic, from which the WDVI index (Weighted Difference Vegetation Index) was generated. For comparison, the normalised difference vegetation index (NDVI), which assesses the crop‘s vegetation stage, was also used. The index values were compared with meteorological data collected from the specific field. The study showed a strong correlation before crop coverage reached 50% ( R = 0.96 and R 2 = 0.94). With dense plant cover, the correlation was weaker ( R = 0.87 and R 2 = 0.77).