Drought Assessment in Karnataka’s Western Ghats Using MODIS-Derived Vegetation Condition Index

Abstract

Vegetation Condition Index (VCI) serves as a crucial remote sensing-based indicator for detecting and monitoring agricultural drought by reflecting deviations in vegetation health over time. This study presents a district-wise analysis of VCI across the Western Ghats region of Karnataka, encompassing six ecologically sensitive districts Kodagu, Shimoga, Chikkamagaluru, Uttara Kannada, Dakshin Kannada, and Udupi for the year 2025. MODIS NDVI data was processed in Google Earth Engine to generate monthly VCI layers, enabling spatial-temporal monitoring of drought severity. FAO/WMO thresholds were applied to classify vegetation conditions into six drought severity classes, with <0.35 VCI indicating drought-prone zones. Comparative time-series analysis between 2024 and 2025 revealed that districts like Kodagu and Shimoga experienced early-season drought in January and April, while Udupi and Dakshin Kannada consistently maintained healthy vegetation. A simplified three-class VCI scheme (Low, Moderate, Healthy) was adopted for intuitive visualization in policy communication.