Observing and Monitoring Drought
Abstract

Abstract Author: Anup K. Prasad, Ramesh P. Singh and Menas Kafatos

Abstract Title: Monitoring and detection of drought conditions using Change Vector Analysis and Standardized Precipitation Index over India

Abstract: The agriculture in India is highly dependent on the monsoon rainfall. With the urbanization and anthropogenic activities the spatial distribution of the monsoon rainfall pattern is found to change that has affected crop productivity. The absolute productivity is found to vary widely with region across India, whereas the crop yield during Kharif season (July-October) is largely found to be controlled by rainfall pattern. During the Rabi season (December-March), agricultural activities are mostly limited to irrigated regions. Crop-weather relationship is very much prominent during Kharif season where a good rainfall is a prime requirement for rice crop. The deficiency in total rainfall due to unusual monsoon rainfall (July-October) leads to drought conditions in various regions every year. Drought conditions are visible in the early stages owing to delay in the sowing of rice crop due to delay or abnormal onset of monsoon. We have used satellite derived data and measures of greenness (Normalized Difference Vegetation Index - NDVI) and productivity (Net Primary Productivity - NPP) as well as measures of precipitation (Standardized Precipitation Index - SPI) since last 10 years to estimate drought conditions. We have analyzed potential of change vector analysis (CVA) on a 10 or 16day composite data (NDVI, NPP) to delineate regions showing drought conditions in the early stages of plant growth in conjunction with satellite based rainfall estimates. We have analyzed 100years of rainfall data to delineate regions which are more prone to drought conditions. The spatial pattern of SPI over India show geographical and temporal (month to year scale) distribution of precipitation anomalies (normal, wet or dry). Precipitation index as well as CVA method helps to study time based response of drought conditions throughout the monsoon season and early detection of drought conditions. The regions affected by the short (limited to a season) and long term drought (recurrence over several years) have been identified using the satellite data.