Assessment of long-term rainfall trends in Maharashtra

Abstract

This research focuses on analyzing the variability, trends, and change points in the annual and seasonal rainfall patterns of Maharashtra, India, over a 120-year period (1901–2020). The study area was chosen due to its significant agricultural importance and vulnerability to climate-related stressors, impacting food production and socioeconomic conditions. Maharashtra exhibits diverse rainfall patterns, with substantial variations across its regions. The research utilizes rainfall data from seventy-four meteorological sub-stations obtained from the Indian Meteorological Department (IMD). For trend analysis, the Mann-Kendall test is employed, known for its effectiveness in identifying trends in hydro-climatic data series. To detect abrupt shifts or change points in the historical rainfall time series, the Pettitt test and the Standard Normal Homogeneity test (SNHT) are utilized. Additionally, the study employs innovative trend analysis, as proposed by Sen, to identify trends in rainfall data without the need for assumptions such as non-linearity or serial correlation. This method offers advantages over traditional parametric and non-parametric tests, providing reliable trend analysis results. While some substations exhibit consistent negative trends, others display positive trends, with notable change points observed around 1961, particularly during the monsoon season. Post-change point analysis reveals varying trends post-1961, emphasizing the need for nuanced understanding across different seasons and substations. Specific substations, including Pune Pashan, Shivaji Nagar, Lohgaon, Bhimashankar, and Dapoli, experience significant negative trends in rainfall, whereas Kolhapur, Ratnagiri, Devgad, Dahanu, and Mitbhav meteorological substations observed positive trend.  This research benefits agricultural planners, water management agencies, environmental groups, and emergency responders by providing insights into rainfall variability. It supports crop planning, irrigation, water management, infrastructure, drought mitigation, ecosystem conservation, and disaster management. It fills a crucial gap in India by using innovative trend analysis to study Maharashtra’s rainfall trends and climate impacts on water resources and agriculture.