Analysis of the Frequency and the Spell of Rainy Days Using Markove Chain Model in Southwest of Iran

One of the most important issues in arid and semi-arid regions is water resources management. Thus the study of the occurrence or non-occurrence of precipitation behavior can improve management water resources in these areas. In this study, the occurrence of days with precipitation in the south west of Iran using daily rainfall synoptic stations in the 1994-2009 periods and adapting Markov chain was performed. The frequency matrix, switching matrix and stable matrix as well as continuous rainfall and the rainfall return periods of 2 and 5 days were calculated. The results show that the minimum probability of rain is in the plain area while the highest probability of rainfall belongs to the mountainous area. Also the highest probability of monthly precipitation is in January and the minimum is that of summer. The minimum of return period and the maximum continuous rainfall are in the mountainous stations and the maximum of return period and minimum continuous rainfall are in the plain area. Also unlike the other months, the maximum of probability rainy days in June is in eastern parts of mountains.