Rainfall trend analysis and future scenario assessment by using mathematical and statistical techniques for South Gujarat

Abstract

In the present study, attempts have been made to study temporal variation in seasonal and annual rainfall over the two districts of South Gujarat during the period 1901 to 2012. The statistical and mathematical analysis of annual rainfall indicates good range of variation of Navsari and Bharuch region for 112 years (1901 to 2012) period. The mean, median, mode, standard deviation, coefficient of dispersion, coefficient of variation and coefficient of skewness of Navsari was found 1515.5 mm, 1430.0 mm, 1444.2 mm, 481.4 mm, 0.318 mm, 31.8%, 0.148 mm and for Bharuch the values were found 972.0 mm, 959.5 mm, 913.7 mm, 293.3 mm, 0.302 mm, 30.2% and 0.199 mm respectively. The annual rainfall over Navsari showed a long term increasing trend, an increase of 304.64 mm only was noticed during the study period of 112 years as against the normal rainfall of 1517.90 mm. Similarly, for Bharuch a decrease of 39.98 mm only was noticed during the study period of 112 years as against the normal rainfall of 972.10 mm. Mode analysis shows class interval 1400 to 1599 has highest number of frequencies of rainfall (21) in Navsari region and for Bharuch highest number of frequencies (32) was found under interval 800 to 999.