Rainfall trends and their influence on crop production in Tamil Nadu, India - A 33-year analysis

Abstract

The purpose of this study was to investigate the effects of annual and seasonal rainfall on crop productivity in Tamil Nadu. From the Tamil Nadu Season and Crop Report for the years 1990 to 2023, the long-term data of annual rainfall, seasonal rainfall, crop production, yield, crop sowing, and harvesting report was obtained. Mann-Kendall and Theil-Sen trend analysis results for seasonal and yearly rainfall over 33 years revealed positive trend patterns, except for NE monsoon. The investigation reveals that the distribution and quantity of rainfall are higher in NE monsoon than in other seasons in Tamil Nadu. Tamil Nadu receives 50 % of rainfall in NE monsoon. The study reveals that the rainfall increases with latitude in NE and SW monsoon. The SW monsoon brings more rainfall than the NE monsoon over Coimbatore and the Nilgiris. The annual rainfall is higher than 500 mm in all years from 1990 to 2023. Tamil Nadu has experienced 5, 22, and 6 excess, normal, and deficit rainfall years during 1990-2023. The annual rainfall is more on land than on the coast. Nevertheless, during the Northeast monsoon, coastal areas receive more rainfall than land areas. Crop production is positively associated with the rainfall than that at groundwater. The functional relations have been established for crop production with rainfall and yield. A significant correlation exists between them with high R-squared, varying mostly from 0.7-0.96, except for cumbu, red gram, Bengal gram, and gingelly. There is a strong relationship between the amount of rainfall and the crop-planting season. Planting these crops at that particular season can thereby increase crop productivity and yield on rain-fed agricultural land. These study findings may enhance the understanding of rainfall's influence on crop production more effectively and increase crop yield through the utilization of water resources in Tamil Nadu.