Assessing Drought Vulnerability in Pakistan (2001-2022) Using EVI-Based Standardized Vegetation Index in Google Earth Engine

This study examines vegetation dynamics and drought risk in Pakistan from 2001 to 2022 using MODIS Enhanced Vegetation Index (EVI) and Standardized Vegetation Index (SVI) processed in Google Earth Engine. EVI highlights high greenness in the irrigated plains of Punjab and Sindh, while SVI exposes widespread stress in these same areas, revealing a “greening paradox” where apparent productivity masks underlying vulnerability. Monthly SVI patterns follow strong seasonal cycles, with positive anomalies peaking during the monsoon driven kharif season (June-October) and persistent deficits occurring in the rabi season (December–May). Spatially, high EVI values (>0.4) were concentrated along the Indus River corridor, while arid zones such as Balochistan and the Thar Desert exhibited low EVI (<0.2). Mean SVI maps contradicted these patterns, showing negative anomalies in high EVI regions. Long term analysis indicated stable EVI until 2018, followed by a modest upward trend, while SVI shifted from chronic negative anomalies in the early 2000s (mean = –0.21) to sustained positive values after 2020 (mean = +0.58). At the provincial scale, Punjab showed a post 2015 decline, Sindh demonstrated recovery after drought episodes in 2010-2012 and 2017-2018, Khyber Pakhtunkhwa displayed high variability without a clear trend, and Balochistan recorded the strongest improvement since 2005. Overall, EVI captured absolute greenness, while SVI provided anomaly based insights into drought conditions, detecting hidden stress in intensively irrigated areas and identifying genuine recovery in marginal regions. By integrating EVI and SVI, this study offers a robust framework for spatiotemporal drought monitoring in Pakistan. The results provide a scientific basis for climate smart agriculture, early warning systems, and sustainable land and water management strategies aimed at safeguarding food security in the face of rising drought frequency.