Rainfall Analysis for Crop Planning for Paddy Grown in Cauvery Delta Zone of Tamil Nadu

Authors

  • JOHNSON B. Department of Applied Mathematics and Computational Science, Thiagarajar College of Engineering Madurai, Tamilnadu, India
  • CHANDRAKUMAR T. Department of Applied Mathematics and Computational Science, Thiagarajar College of Engineering Madurai, Tamilnadu, India
  • SAKTHIPRIYA D. Department of Applied Mathematics and Computational Science, Thiagarajar College of Engineering Madurai, Tamilnadu, India

DOI:

https://doi.org/10.54386/jam.v28i3.3270

Keywords:

Cauvery Delta Zone, ENSO, Innovative Trend Analysis, Mann–Kendall test, Rainfall probability, Sen’s slope

Abstract

The Cauvery Delta Zone (CDZ) of Tamil Nadu is highly dependent on rainfall variability for paddy production. The long-term daily rainfall data (1991–2024) from three representative districts (Thanjavur, Tiruvarur, and Nagapattinam) were analysed to evaluate the rainfall trends, regime shifts, and assured rainfall for crop planning. Non-parametric Mann–Kendall and Sen’s slope tests were used to detect monotonic trends, while Innovative Trend Analysis (ITA) and Pettitt’s change-point test identified non-linear trends and structural shifts. Weekly rainfall probabilities were estimated using the incomplete gamma distribution. Results indicated a statistically significant increase in Northeast Monsoon rainfall (Sen’s slope: +3.1 to +3.7 mm yr⁻¹; p ≤ 0.05) and a weak decline in Southwest Monsoon rainfall (−0.9 to −1.4 mm yr⁻¹). Pettitt’s test detected a significant rainfall regime shift around 2005 (p < 0.05), marking increased interannual variability. District-wise probability analysis showed that Standard Meteorological Weeks (SMW) 42–48 provide assured rainfall ≥75 mm at 75% probability, suitable for Samba paddy transplanting, whereas Navarai season rainfall was unreliable (<10 mm week⁻¹). Regression analysis revealed that ENSO and IOD together explained 82% of interannual rainfall variability (R² = 0.82; p < 0.01). The study provides statistically robust, rainfall-responsive insights for paddy crop planning in the Cauvery Delta Zone.

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Published

07-09-2026

How to Cite

B., J., T., C., & D., S. (2026). Rainfall Analysis for Crop Planning for Paddy Grown in Cauvery Delta Zone of Tamil Nadu. Journal of Agrometeorology, 28(3), 415–421. https://doi.org/10.54386/jam.v28i3.3270

Issue

Vol. 28 No. 3 (2026): September

Section

Research Paper

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Copyright (c) 2026 JOHNSON B., CHANDRAKUMAR T., SAKTHIPRIYA D.

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