Innovative trend analysis of monsoon season rainfall of Kerala state

Kerala is a maritime state, located in the southern part of India.The onset of monsoon in Kerala initiates the Indian summer monsoon which is vital for India's agricultural economy and rainfall distribution (Pattanaik and Bushair, 2024).It marks the shift from dry to rainy season, influencing the time and period of monsoon rain nationwide (Pradhan et al., 2017).The state's agricultural economy heavily depends on summer monsoon rainfall (SMR).The SMR in the state is also an important source of freshwater.Any significant change in the SMR may impact crop growth and freshwater availability, hence, it becomes important to study the trend pattern of the SMR in the region.Trend analysis involves using statistical methods that identify the trend in the data.A statistically significant negative trend indicates reduced rainfall over time, which impacts crop growth and freshwater availability.In contrast, a statistically significant positive trend indicates increased rainfall, influencing water resource management and ecosystem sustainability.Administrators also benefit from understanding rainfall patterns as it facilitates informed decisions on water resource allocation, while it is helpful to farmers in strategic crop planning.Various statistical methods, viz., Mann-Kendall (MK) method, Sen slope (SS) method (Shankar and Sharma, 2025) Spearman's rank correlation method, modified Mann-Kendall method (MMK) (Ghanim et al., 2023), sequential Mann-Kendall method (SQMK), discrete wavelet transform (DWT) method, innovative trend analysis (ITA) method (Al-Lami et al., 2024), have been used to detect the trends in rainfall.Adarsh and Janga Reddy (2015) used the MK, SS, SQMK, and DWT tests for the detection of trends in the rainfall pattern of four subdivisions in southern India.By analyzing the data of 140 years (1871-2011), they have found an increasing trend in the rainfall for all the subdivisions except Kerala, in which a decreasing trend has been found for seasonal and annual rainfall (Adarsh and Janga Reddy, 2015).Nikhil Raj and Azeez (2012) analysed the trends in the rainfall pattern of the