Application of statistical and geostatistical approaches in temporal and spatial estimations of rainfall

Abstract

This study is the first study that worked on the temporal and spatial distributions of annual rainfall (Pyear) and maximum 24-h rainfall (Pmax24h) in the Semnan province. For this purpose, different statistical distributions were used to estimate the temporal Pyear and Pmax24h in the Semnan province. Six synoptic stations across the province were studied and all stations had complete Pyear and Pmax24h data. Different return periods were studied. The goodness fit test of statistical distributions for Pyear showed that about 67% of the stations follow the Generalized Pareto (GP) distribution. Considering the Pmax24h, 50% of the stations follow the GP distribution, and for the ratio of Pmax24h to Pyear, 50% of stations follow the Generalized Extreme Value (GEV) distribution. The spatial distribution of Pyear and Pmax24h showed that in all return periods, by moving to the southeast of the province, precipitation amounts decreased. While moving toward the Shahmirzad station, the amounts of Pyear and Pmax24h increased. Also, there was a logical relationship between the Pyear and Pmax24h. Consequently, the minimum value and the maximum value of the R2 coefficient in different return periods were equal to 0.992 and 0.980, respectively. HIGHLIGHTS Statistical analysis was effective in calculating the highest average annual rainfall and the highest average 24-h load.; The use of geostatistical methods and statistical distributions shows a good performance in predicting the amount of precipitation.; The use of statistical distributions and geostatistical methods can be appropriate in locating the establishment of a meteorological station.;

Keywords

• annual rainfall (pyear)
• maximum 24-h rainfall (pmax24h)
• spatial distribution
• semnan province
• time distribution