Spatio Temporal Analysis of Historical Precipitation Variability and Rainfall Extremes in Badamalehra, Chhatarpur District, Central India

Abstract

Erratic and extreme rainfall strongly governs rain-fed farming and water availability in drought-prone Bundelkhand, a semi-arid tract of central India. In this study, 33 years (1990–2022) of daily observations from the Badamalehra rain gauge, Chhatarpur district, Madhya Pradesh, were examined to describe how rainfall behaves, shifts and peaks at month, season and year scales. After screening for errors, the daily values were aggregated into month, season and year totals. Dispersion was quantified through the CV (coefficient of variation), the PCI (precipitation concentration index) and IMD departure categories. Monotonic tendencies were examined with the Mann–Kendall statistic and their size with Sen's estimator, step changes were located with Pettitt's procedure, and extremes were described using thirteen ETCCDI and IMD indices. Mean yearly rainfall amounted to 1200.3 mm (CV 26.7%); the June–September monsoon supplied 94.3% of this total, and July and August alone contributed 62.8%. The non-monsoon seasons exhibited very high CV (196 to 224%) and the mean PCI was very high (32.8%) suggesting a strongly seasonal rainfall regime. For the 33 years 16 years were the normal years, 9 years were the excess years and 8 years were the deficient years, the deepest being 2007 (−54.7%). The annual rainfall (−3.09 mm yr−1) and monsoon rainfall (−5.66 mm yr−1) exhibited non-significant downward trends, respectively, and did not contain any significant change point. Rainfall in the month of September experienced a significant (p < 0.01) decreasing trend between 1990-1999 and 2010-2022, with more years of deficiency after the year 2000, while the rainfall during winter and pre-monsoon showed strong increasing trends (p < 0.01). No significant changes in extreme intensity or extreme frequency for the precipitation occurred, but very wet days still supply roughly a quarter of yearly rainfall, while the longest dry spell shortened significantly (−1.88 days yr⁻¹). These outcomes point to the value of capturing rainwater, conserving soil moisture on the field and preparing alternate crop plans to cope with late-season monsoon failure at Badamalehra.