Drought assessment using multivariate indices in the sub-basins of the Vaippar River Basin, Tamil Nadu, India

Drought is a serious natural hazard caused by a lack of precipitation in relation to what is expected or normal, which, if prolonged over a season or longer time, is insufficient to fulfil human activity demands. It is a seasonal, localised natural occurrence of the climate. Droughts are thus primarily brought on by precipitation deficits brought on by regional and temporal natural climate variability. Droughts cannot be stopped, but their effects on people and plants can be lessened by being well-prepared for their likely occurrence. India experienced a 22% total rainfall deficiency in 2009, which reduced food grain production by 16 million tonnes. The drought that affected a considerable portion of the nation in 2014, 2015, and 2016 caused significant problems for the affected populace since it devastated important agricultural regions of the nation. The Arjunanadhi sub-basin typically experiences heat and drought every five years, according to the project report for Irrigated Agriculture Modernization and Water-Bodies Restoration and Management (IAMWARM). The purpose of this research is to pinpoint the variable that causes drought in the Vaippar river's sub-basins of Arjunanadhi and Koushiganadhi. The Standardized Precipitation Index (SPI) for meteorological drought, the Water Requirement Satisfaction Index (WRSI) tool for agricultural drought, and the Herbst method for hydrological drought are used to establish a link between crop production and crop area. Meteorological, hydrological, and agricultural drought are assessed using a variety of methods, including GIS, Multivariate Analysis, and the use of different indicators. Based on the return period of drought calculated using SPI for the Arjunanadhi and Koushiganadhi sub-basins, the overall drought happens once every three to four years. When the land is used for paddy and sugarcane, the Arjunanadhi and Koushiganadhi sub-basins' Water Requirement Satisfaction Index is extremely susceptible to drought. The stream flow statistics from the reservoirs at Anaikuttam and Kullursandai indicate that the Arjunanadhi and Koushiganadhi were impacted by severe and extreme drought, according to the hydrological drought evaluation's negative indicators. As per multivariate analysis, rainfall is the factor most likely to influence the probability of drought since the independent variable crop production has a better correlation with the SPI indices and crop area.