Statistical Analysis of High- and Low-Precipitation Areas of Iran

Investigating and analyzing the causes of droughts and destructive floods in Iran, which is facing a water shortage, is an essential issue. One of the goals of this research was to identify the extent of areas with more or less than the average precipitation during the study period.

The data used in this article was the daily precipitation of 117 synoptic stations in Iran during 1986-2020. Calculations were done through MATLAB 2013, Excel 2013 and SPSS 22 software, and Surfer 24.3 software was used for interpolation and drawing of maps.

The most precipitation October, the least precipitation November, and the least precipitation January during the 35 years studied were observed in 1987. January and February in 1996 were in the highest range of precipitation above their average. In March and May 2008, most of the country had a lot of precipitation. Absolute low precipitation was observed in November and January 1987 for all the studied stations (117 stations). Most of the stations with higher-than-average precipitation were in March 1996 with 102 stations. In January and December, compared to other months of the year, higher-than-average precipitation was seen with a greater extent. So that in 15 years, most of the stations involved in the load were higher than the average. In June, only in 3 years most of the stations had above average precipitation and the rest of the years the number of stations with high precipitation was very low.

The country's precipitation occurs in small areas most of the time. Even though, precipitation below the average occur for all stations, but rainfall above the average does not occur for all stations.