Multivariate analysis of concurrent droughts and their effects on Kharif crops—A copula‐based approach

Abstract

Apart from creating an ecological imbalance, drought events could affect an agrarian country's economy and food security by reducing crop yields. The antecedent meteorological droughts could prolong into hydrological and (or) agricultural droughts and may co-exist as concurrent droughts. The current study aims to comprehensively study Indian concurrent droughts, their effects on crop yield, and possible teleconnection with ENSO (El Niño-Southern Oscillation), adopting a copula-based multivariate approach. The copula functions can replicate the correlation among the variables and keep the dependence structure intact. The concurrent drought characteristics are computed using a multivariate standardized drought index that incorporates the three primary drought indices using the Gaussian copula. Some of the severe concurrent drought years such as 2002, 1987, 1972, and 1965 caused considerable yield losses in Kharif season crops of groundnut, millet, and rice. This prompts to construct quad-variate models involving the crop yield and the three drought indices using the vine copulas that perform better than the elliptical and symmetric Archimedean copula. Though the isolated forms of droughts could cause mild yield losses, the probability of concurrent droughts causing high to exceptional losses is more. Further, the ENSO teleconnection with the concurrent monsoon droughts is analysed and mapped. The above-normal warming of the Nino 3.4 region over the tropical Pacific during the months leading up to the monsoon could signal concurrent monsoon droughts in the areas under the Ganga-Brahmaputra basin at a probability of around 45%. These results could be helpful in drought mitigation measures and policymaking.copula, drought, multivariate analysis, vine copula | INTRODUCTIONIn India, 14.5% of people are malnourished, and 37.9% of children under age five are stunted as of 2018 (Priyadarshini and Abhilash, 2020). Sustaining food security in an evergrowing population is one of the challenges posing the developing countries. With the increasing population, urban expansion could sprawl into agricultural farmlands (Abu Hatab et al., 2019). Thus improving the crop yield with advanced farming machinery, pesticides, insecticides, irrigation practices, or sowing high yielding variety seeds become the need of the hour (Sannigrahi et al., 2021). Despite these measures, the inevitable climate extreme events such as extreme precipitation (Alidoost et al., 2019)