Studying the synoptic patterns governing the happening of large flood in karoon basin

The flood, undoubtedly, is one of the natural disasters. In fact, flood is rising the water level of river therefore water overflow and occupying the some parts of plains of the riverside that may swamp the region which cause damages to structures and public facilities as well as human and animals fatality. In some cases, the flood could be due to rise the sea and lake level in which the severe winds would have a great impact. Considering the importance of the subject, floods of Karoon basin were considered; 12 hydrometric stations were used for analyzing the floods in the basin during the period of 1986-2015.to study time series data, run test and normality homogeneity have done; then, positive values ​​between the two consecutive zero points were assigned as a calculate base to determine the flood continuity time. According to identified huge flood basin with the highest runoff volume of basin, high atmospheric data from the National Center for Environmental/Science Forecast (NCEP/NCAR) in 2.5/2.5 resolution networks Degrees were extracted. The study indicates that 4 patterns were involved in the flood happening of the region. The analysis shows that the highest frequency of flood happening in the region is in April. The Caspian Sea and the Mediterranean Sea as a pair and the Red Sea in the transfer of moisture to the region was identified as the humidity sources in the region.