JOURNAL OF PHYSICAL GEOGRAPHY
Year:2009 | Volume:1 | Issue:4|Papers Count:8

In this article, the heavy precipitation period of 7 to 14 March 2005 (16 to 24 Esfand 1385) in West of Iran as an example has been studied. In order to synoptic analysis of mentioned precipitation, daily surface, 850 and 500 Hectopascal air maps is used. This analysis has been done from 48 hours prior to cut full day rainfall. Climatic elements that studied in this analysis include: Daily rainfall and humidity in selected stations in the West of Iran. The results show that low-pressure system in the Mediterranean Sea and the Sudan low through are cause of the precipitations and the Mediterranean Sea, Black Sea and Red Sea in strengthening these systems have importance role. In first day of precipitation, in surface the Mediterranean low-pressure system from northwest and the Sudan low pressure from southwest the Country have been moved to studied area. In the day of rainfall peak, the merge of these systems caused heavy rainfall in the area. On March 13 with exiting of mentioned systems, has been started a stability conditions in the area by progressing of Siberian high pressure system. In the upper levels on first day of rainfall, the through axis along on Turkey, Iraq and the Persian Gulf and west borders of the region. With Moving of the short-wave and change its axis position toward the East, in the surface, the Mediterranean low-pressure has to move forward simultaneously. In this case, all regions in West, located in the east of through and caused of intensified of instability condition and heavy rain.

One of the most important matters for big cites all over the world is the problems of natural hazard.as natural hazards are unpredictable and we should decide about them very fast and correctly, the re has been established a science named "Crisis Management". this is a science that works before, through the crisis and afterwards to reduce the effects of it and the vulnerability.Doing through urban management rules and releasing the concepts of this science like the structure of the city, urban land use and communication networks, we can reduce the effects of natural hazard considerably. The Khoram Abad city is involved by this problem. As this city is located among the Zagros Mountains and lots of rivers in this area and the faults situated under the city, so it is very vulnerable by natural hazard.

The geographical basin of Lashak is located in Nowshahr in Central Alborz, Iran. The aim of the research was to fin the orgin of the sediments in the basin. To achieve the aim we analyzed 40 samples from sediments by XRF and XRD. Also we studied 25 thin sections from these samples. The petro graphical and mineralogical results show that the sediments have been originated from shale, sandstone and siltstone of Ruteh and Shemshak formations. The geochemical results show that the sediments are high in TiO2 , Al2 O3 , Ag, Cu, Mo, Ni, V and low in MgO, MnO, CaO, Sr, Sb, As relative to Clarke standard. The sediments are mainly composed of clay minerals like mica, illite, kaolinite, montmorillonite, ploygurskite, nantronite, and chlorite, quartz and carbonate. The amount of ploygurskite is higher than other clays. The high PH and presence of carbonate is the main reason of formation this mineral.

Frost is one of climatic phenomenon by damaging in economic difference sections specially: agricultural. So, it's important to identify this phenomenon in Fars province, because of agricultural activities.The aim of this research to recognize circulating patterns in atmosphere levels for frost occurrences. It can forecast from mapping of air different levels. So, with application principle component analysis up to correlation matrix on geopotential height in 500HP level and see level pressure data in geographical limits 0-70 eastern longitude and 20-60 northern latitude to identify essential elements of atmosphere formation circumstance. Afterwards, the usage of clustering analysis with ward method on components scores, identified circulating patterns.As a result, Siberian high pressure and high pressures of European north and northeast extend toward Iran to reduce degree of temperature in Fars different regions. In addition to The core of high pressure more than 1025HP is formed in Zagros heights that to play basic role in the intensification and durability of province frosts. In 500HP level with settlement ridge eastern section of Fars province it is caused to move very frigid air from up latitude toward low.In this situation the degree of air petered in different regions of Fars. Particular, in the northern, central and northwestern parts.

In this study in order to regionalize the areas in south and south west of Iran for agricultural studies, 44 synoptic stations located in Khuzestan, Charmahal Bakhtiari, Ilam, Kogeluyeh and Booyer Ahmad, Hormozgan, Fars and Bushehr, were selected. Obtained data of 15 climate parameters effecting on agricultural crops were collected for a 20 year period. In order to determine the most effective climate-agricultural parameters, the method of Principal Component Analysis (PCA) was utilized. The first three components causing 85% of variances of variables were selected and among these three components, 11 variables were identified as the most effective climate-agricultural parameters. These parameters include: Average of minimum temperature, Average of mean daily temperature, Number of days with maximum temperature equal 30 and above, Number of days with precipitation, Number of days with thunder storm, Number of cloudy days, Average of relative humidity, Monthly total of precipitation, Number of days with snow or sleet, Number of clear days, Number of partially cloudy days. Data obtained from selected climate variables, were analyzed by cluster analysis (Average linkage). After obtaining the dendrogram, it was cut in the place that 9 climate regions were produced for 44 selected synoptic stations. Moreover, in order to evaluate of obtained results of cluster analysis, discriminant analysis was utilized. The results indicated that 97.7% of synoptic stations were placed in their right groups correctly. Relative similarity in vegetation and crop types in each climate class indicated that the derived climate classification could be used for agricultural studies as a general guidance.

One of the basic problems of metropolitans & great cities is rapid population growth & physical development. For appropriate control of physical development & urban expansion, it is necessary that moreover socio-economic analysis, recognition & accurate analysis of earth properties is available. Assessment of land suitability can be useful for spatial & urban planning. The aim of this study is to recognize susceptible area for physical development in karaj city & suburbs on the base of natural factors. These factors & materials include topographic, geologic, land cover/land use, seismologic maps and related data concerning the climate and population of the area. Library studies are complementary data indeed. The assessment of land suitability was carried out by nine natural factors consisting: slope, lithology, distance from faults, capability for agriculture, seismology, distance from rivers, land cover/land use, depth of groundwater, type of landform and Analytic Hierarchy Process (AHP) method in geographic information system (GIS). Land suitability is classified into five classes: very high, high, moderate, low, very low and its zonation map was illustrated. The results show that apart from agricultural lands, 31% of the area is settled in very high and high classes that further are located in south & west of area. Results show that in 3 recent decades urban development is occurred more on very high and high suitability classes. In spite of this subject, about 500 hectares of urban texture is developed in low & very low suitability classes in the rapid slopes & margin of mountains.

At three different height 170, 130 and 5 centimeters above the surface and at 06:30, 12:30 and 18:30 LMT (+3:30 GMT), in irrigated and non-irrigated days, in the Botanic Garden of agriculture and natural sources faculty of Tehran University, in 62 days of summer time that there were 15 days alternatively with sprinkler irrigation (7 days irrigation in the morning and 8 days in the afternoon). Results shows that irrigation in the morning (8:00 - 11:30 LMT) decreases dry bulb and maximum temperature and increases wet bulb temperature and relative humidity, whereas, irrigation in the afternoon (13 - 16:30) results in increased dry bulb, minimum and maximum temperature and decreased wet bulb temperature and relative humidity in all times and height that were observed.

In resently years in the world scientific circles have been discussed the subject of climate changes. in this research, the changes of time oscilation of the number of frost days in duration 1978-2005 in the nortern Khorasan. In first researches or specifying the trend of data have used of Kendal mean and then clear that the number of frost days have descending trend. This trend have conformity to increasing trend of annual temperature mean. In later stage for fitting a suitable time series model to data used of Box-Jenkins method. First, data series becom stationary to using of difference transformation. Then have been drawn Autocorrelation and Partial Autocorrelation curves and studied stationary particulars and omission of variance. At the end, the model of ARIMA (0, 0, 2) have been distincted suitably. Calculated data in confidence level have been confirmed. For test of fitting, with to using of Regression method distinguished that the time series model has fitness to data in confident level. This model shows that the number of frost days in coming years will have descending trend with oscilation.