Retrospective Trend Analysis of Seasonal and Annual Rainfall Data in the Middle Gujarat Agro-climatic Zone, India

Abstract

Aims: To analyze the trends in seasonal and annual rainfall data series in the Middle Gujarat Agro-climatic zone, India, over a 30-year period (1991–2020) to inform water resource planning and management in a rainfed agricultural region. Study Design: A retrospective trend analysis using the Mann-Kendall test and Sen’s slope estimator technique. Place and Duration of Study: Middle Gujarat Agro-climatic zone, Gujarat, India, with data analyzed for the period from 1991 to 2020. Methodology: Seasonal and annual rainfall data for the Middle Gujarat Agro-climatic zone were analyzed over a 30-year period (1991–2020). The Mann-Kendall test was used to detect trends, and Sen’s slope estimator was applied to quantify the magnitude of trends. The analysis focused on monsoon, post-monsoon, pre-monsoon, and winter seasons, with statistical significance tested at a 95% confidence level. Results: No significant trends were detected for seasonal or annual rainfall data series at the 95% confidence level. Non-significant rising trends were observed, with increases of 33 mm per year for the monsoon season, 1 mm per year for the post-monsoon season, and 33 mm per year for annual rainfall. Pre-monsoon and winter seasons showed no rainfall contribution. These trends suggest a tendency toward wetter conditions over time. Conclusion: The absence of significant trends in rainfall data indicates no clear evidence of climate change-induced variations in rainfall patterns in the Middle Gujarat Agro-climatic zone. Communities are recommended to adopt sustainable water management practices to ensure continuous water access in this rainfed region.