Assessment of Normalized Difference Vegetation Index based vegetation dynamics for monitoring rice growth and yield forecasting in the Mahaweli H region of Sri Lanka

This study analyzes the possible relationship between Normalized Difference Vegetation Index values and rice yield in the subregions of the Mahaweli H agricultural zone in the North Central part of Sri Lanka. The analysis focuses on the Maha season (September– March), which is driven by the Northeast monsoon and is the main rice growing season in this region. Seasonal Normalized Difference Vegetation Index dynamics were calculated over a 5-year period from 2018 to 2022. Based on the obtained values, the correlation between Normalized Difference Vegetation Index and rice yield was assessed. The results showed a strong positive correlation between the studied indicators in the subregions of Thambuttegama, Nochchiyagama, Madatugama, and Eppawala. In the regions of Talawa, Meegalewa, and Galnewa, negative correlation coefficients were recorded. Yield forecasting models developed for the subregions with positive correlations demonstrated high accuracy, confirming the potential of Normalized Difference Vegetation Index as a reliable indicator for rice yield prediction. These findings highlight the value of satellite-based remote sensing in identifying spatial variability in yield and supporting adaptive agricultural management aimed at enhancing productivity and food security.