Probable maximum precipitation (PMP), is the highest rainfall, which occurs at a given time in a basin. Hydrologist calculates the probable maximum flood for the design of overflow dams, by using the PMP, with two methods: statistical and synoptic. The purpose of this study is calculating PMP in the Ghomrood basin by using the synoptic method. For this purpose rain, meteorological data of the Iran’s Meteorological Organization were used. Also, the data on the 850 and 500 hPa levels were analyzed by the National Center for Environmental Prediction and the National Center for Atmospheric Research (NCEP-NCAR). In the following, the required synoptic maps produced and were studied. Iso rain maps were drawn, and depth-area-duration curves were determined. Eventually, PMP was estimated at 24, 48 and 72 hours. So that 24 hours PMP, by calculating 50 and 100 years return period of dew point estimated 51/75 and 54 mm respectively. Also for 48 hours PMP 128/25 and 132/05 mm, and for 72 hours PMP 97/9 and 101/75 estimated.

In this study, the changes in the Khorramabad storm in the period of 1952 to 2015 have been investigated. For this purpose, data from meteorological codes 06 and 07 were received from the Meteorological Organization of the country, and after identifying the days of winding with dust storms and calculating their monthly frequency, monthly, seasonal and annual time series were analyzed. In this study, descriptive statistics, cluster analysis, linear and polynomial trend analysis, and nonparametric Mann-Kendal test were used to study the frequency variation of dust storms in Khorramabad station. The results of the research showed that the monthly frequency of dust storms in Khorramabad station in the middle of May, July and June is May and July, respectively, and from May to July (May to July), the frequency of storms in the dust and dust Khoramabad station is added that this issue is not related to the district heating and dry season. In the seasonal season other than the autumn, which is not frequent with frequent dust storms, in the rest of the seasons, especially in spring and summer, the seasonal concentration of dust storms in Khoramabad has been intensified. The analysis of the trend of time variation in the occurrence of dust storms in Khorramabad station showed that in most of the months of the year and in the three seasons of spring, summer and autumn, as well as in the annual period, there was a significant change in the frequency of dust storms in Khorramabad station. It is increasing with a relatively steep slope, indicating that in the future, the frequency of dust storms in Khorramabad station will be increased.

 Studies show that 14 provinces are impacted by wind erosion and the movement of sand dunes. The sand originated from the shores of Oman Sea is the most important environmental hazards that threaten the already large number of rural settlements. Sands of marine origin are available on the beach and away from the sea of dunes in addition of marine origin, Predictive models for planning sustainable use of land use and land cover in a country like Iran that land use is changing rapidly, there is an urgent need; To detect and predict changes in land cover changes overview to better manage natural resources and protect marginal lands beaches and is very effective long-term policy measures. The aim of this paper is  modeling and prediction of changes in  land-use in 2035 by using  CA Markov model and Landsat satellite images in the West of Zarabad,( The coasts of Makran). Then to determine the changes in the movement of sand dunes in the study area ranged from twenty-three years (1991-2014), satellite imageries from Landsat 7 and 8(ETM+ sensor) with 15 and 30 meters spatial resolution , was used. The 1991, 2001and 2014 month August images were used, this images from website of the US Geological Survey (USGS) have been prepared. Finally, these images by using Geographic Information System (GIS), ENVI and IDRISI softwares were analyzed. The results  showed that the changes in the region the largest increase in the interest of sand dunes in the year 1991 (25.561) km², in 2001 (10 . 568) km², and in 2014 (45.578), and the increase of (17.198) km², has experienced. The results also estimated that in future (2035) sand dunes area increase to 592.45 km².This  increase in area of sand dunes occur in the absence of proper and efficient management is done in order to stabilize the sand. This increase resulted from changed moorland 162 km²of land area (27%) and 12 kilometers of vegetation (2%) and 23 km² of fluvial (3.4%). These changes makes heavily exposed about 6 villages (Karti,Gnjk, Sohroki, Pyvshk, Vanak and Kalirak) to the movement of running sands.

This study aimed to investigate the temporal-spatial and synoptic features of thunderstorms in southwest of Iran (Khuzestan, Chaharmahal & Bakhtiari and Kohkiluyeh & Boyerahmad Provinces) It was compiled using volatility indices during the period 1985-2015. Results of Frequency Analysis of Thunderstorms at Dezful Station with 479 cases the highest frequency and Ramhormes with 252 days had the lowest frequency. In terms of seasonal distribution, spring was the most abundant with 39%. On a monthly basis, April had the lowest frequency with 21% and August with only 2 cases. In terms of thunderstorms the highest frequency of thunderstorms with no thunder was 21 percent. Synoptic analysis: Most of the time there is a nave (at level 500) or low pressure in the west of the region, east of the Mediterranean Sea with its tabs clockwise. From the Red Sea and the Persian Gulf, they entered the south, southwest, and west of Iran On the other hand, the high-pressure system on the Gulf of Aden in the east of the region is round in the clock It has injected moisture, especially at a level of 850 millibars. Interaction between the two systems over the course of the day, It has injected moisture from three sources of the Mediterranean Sea, the Red Sea and then the Persian Gulf into the rising systems of the region. The low-pressure counterclockwise movement of the eastern Mediterranean, Along with the high-altitude clock movement over the Gulf of Aden, it has injected moisture at levels of 850 to 700 degrees.