Investigation of Rainfall Variability and Trend of its Disorder Index in South Coastal Belt of the Caspian Sea

The Caspian Sea south coast is known the wettest area of the Iran where has the most rainstorms value in 24 hours time, Thus this special situationassociate with the world climatic changes in recent years caused that by 6 stations used to identify of line trend related to seasonal rainfall and itsdisorder index changes over the three last decades of twentieth century. The primitive results have shown in spite of the fact that the most negative anomalies of rainfall were happened in Winter and Spring on the Southeast and Southwest regions respectively, only the Autumnal rainfall is facing with an increase in middle section of the coastal belt. Also with regard to decline of the most rainstorms value in 24 hours time in Autumn above the Anzali site and its rise above the Ramsar and Babolsar sites, it is probable that the frontier of intensive rainfall has been diverged from Southwest area along coastline towards East. Concerning of the warm semester can be pointed to the trend of its rainfall decline on this area throughout. In continuation has been shown that the annual disorder index on the some places is increasing, but the addition tendency towards heavier daily rainfall over the Southeast basin in spring and summer seasons and over the Western Mazandaran province in Autumn have encountered with a special position on the coastal belt.