A comparative analysis of four drought indices using geospatial data in Gujarat, India

摘要

Rainfall deficiency results in drying up of soil, leading to a drought situation, invariably with grave consequences. The magnitude and pattern of drought can be measured with various drought indices using remote sensing and meteorological data. The present study attempts to analyze spatio-temporal pattern of drought severity, and compare meteorological and vegetative drought indices in Gujarat, an agrarian and drought-prone state in western India. Open source remote sensing and rainfall datasets were analyzed for the monsoon and non-monsoon seasons from 1982 to 2001, a period underscored by 12 major droughts. Four indices, namely Standardized Precipitation Index (SPI), Rainfall Anomaly (RFA), Vegetation Condition Index (VCI), and NDVI Anomaly Index (NAI) were used for analysis. Drought patterns, thus delineated, were found to have very good correlation with rainfall. It was observed that both RFA and NAI could be used as an indicator for assessment of the percentage of area affected by meteorological and vegetative drought in the study area. A comparison between the four indices was of much help in understanding the impact of meteorological drought on vegetative drought. Furthermore, multiple regression analysis revealed that RFA and NAI were better-suited drought indices, among the four under consideration.