Frequency analysis for one day to seven consecutive days annual maximum rainfall for Kohima (Nagaland), India
Frequency analysis for one day to seven consecutive days annual maximum rainfall
Abstract
ABSTRACT
In this study, daily rainfall data recorded at Kohima (25° 40’N latitude, 94°07’E longitude altitude 1420 m) over a span of 26 years (1997-2022) were gathered. As there's a lack of information on the frequency analysis of annual 1-day to seven consecutive days annual maximum rainfall in Kohima, Nagaland, this study fills that gap.
A turning point test suggested that one to seven consecutive days annual maximum rainfall could be considered random. A Lognormal probability distribution function was found to be the best fit for 1-day annual maximum rainfall data, while a Log-Pearson Type III probability distribution function was found to be the best fit for 3, 4, and 6-days consecutive days annual maximum rainfall data. Extreme value type-I probability distribution function was found to be the best fit for 2, 5, and 7-days consecutive days annual maximum rainfall data.
For a recurrence interval of every two years, an annual maximum rainfall of 72.9 mm in one day, 93.8 mm in two days, 107.18 mm in three days, 119.98 mm in four days, 132.68 mm in five days, 138.58 mm in six days, and 158.98 mm in seven days is expected. For a recurrence interval of 100 years, the expected annual maximum rainfall in one day, two days, three days, four days, five days, six days, and seven days are 144 mm, 188.1 mm, 199.8 mm, 269 mm, 270.2 mm, 332.9 mm, and 324.4 mm, respectively.
Single-parametric models were developed for 1-day as well as 2-7 consecutive day annual maximum rainfall corresponding to 1-100 years return period. The coefficient of determination ranged from 0.964 to 0.997. Relationships were established for 2-7 consecutive maximum rainfall with one-day annual maximum rainfall, with the coefficient of determination varying from 0.994 to 0.997. It's important to note that these relationships are specific to the data used, and their application can significantly simplify the analysis of long-term data for individual stations.
Keywords: Consecutive days annual maximum rainfall, Turning point test, Continuous probability distribution function, Regression models
