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Summary statistics of monthly and annual rainfall data are given in Table 1. September is the wettest month (rainfall amount equals 112.5 mm) with the highest variation in rainfall. The driest month is February (rainfall amount equals 56.4 mm) with the second highest variation. The skewness coefficient computed for monthly and annual rainfall data is presented in Table 1. The data usually fit normal distribution, if the skewness is very small or close to zero (Robertson 2008). Small skewness values in Table 1 indicate that all data sets are almost normally distributed. Furthermore, it is evident from the K-S test results (Table 1) that the null hypothesis cannot be rejected at 5% significance level because the computed K-S test statistic values for all data sets are smaller than the corresponding critical value (i.e., 0.30143). In this study, the null hypothesis is defined as the condition that indicates the data follow normal distribution. Thus, the rainfall data sets are found normally distributed at 5% significance level and can be directly used for variogram modelling and spatial interpolation.

Table 1

Summary statistics for the monthly and annual mean rainfall data (n = 19)

 Rainfall (mm)
  
PeriodMeanStd devMinimumMaximumSkewnessK-S value
January 67.3 31.2 1.8 201.4 0.2796 0.14971 
February 56.4 53.4 0.0 269.5 0.3156 0.12822 
March 66.3 36.9 9.2 217.8 0.2800 0.16618 
April 84.7 45.8 15.2 246.0 0.0176 0.15649 
May 88.3 42.5 10.2 239.7 −0.1027 0.19500 
June 106.4 46.2 13.8 300.2 −0.0522 0.16641 
July 102.1 49.0 17.9 303.9 −0.0745 0.14543 
August 108.6 50.7 21.1 289.7 −0.0029 0.12252 
September 112.5 57.0 25.3 350.3 0.0330 0.15424 
October 101.6 50.9 4.0 333.9 −0.0988 0.17993 
November 96.1 47.6 15.3 258.7 0.0659 0.14956 
December 91.3 52.9 8.2 301.2 0.0469 0.16043 
Annual 1081.6 293.8 508.1 1913.9 −0.0756 0.14468 
 Rainfall (mm)
  
PeriodMeanStd devMinimumMaximumSkewnessK-S value
January 67.3 31.2 1.8 201.4 0.2796 0.14971 
February 56.4 53.4 0.0 269.5 0.3156 0.12822 
March 66.3 36.9 9.2 217.8 0.2800 0.16618 
April 84.7 45.8 15.2 246.0 0.0176 0.15649 
May 88.3 42.5 10.2 239.7 −0.1027 0.19500 
June 106.4 46.2 13.8 300.2 −0.0522 0.16641 
July 102.1 49.0 17.9 303.9 −0.0745 0.14543 
August 108.6 50.7 21.1 289.7 −0.0029 0.12252 
September 112.5 57.0 25.3 350.3 0.0330 0.15424 
October 101.6 50.9 4.0 333.9 −0.0988 0.17993 
November 96.1 47.6 15.3 258.7 0.0659 0.14956 
December 91.3 52.9 8.2 301.2 0.0469 0.16043 
Annual 1081.6 293.8 508.1 1913.9 −0.0756 0.14468 

Std dev, standard deviation of rainfall; K-S value, Kolmogorov–Smirnov test statistic value, K-S19, 0.05 = 0.30143.

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