GEOGRAPHICAL RESEARCH
Year:2008 | Volume:23 | Issue:1 (88)|Papers Count:7

In the present paper using wavelet analysis, fourier analysis and statistical analysis we examine the role of the sunspots on the annual precipitation variation and take indicator stations of 7 precipitation regions of Iran. The results indicate that variation of annual precipitation is closely related to the variation of sunspot numbers. Mean annual precipitation in Iran; have a certain variations corresponding with 5,8, 11 and 22 year sunspot cycles. Correlation between sunspot activity and annual precipitation variation is not constant and varies along coastal and inland areas in Iran. Therefore, precipitation variations at northern coastal areas in Iran, positively correlated with sunspot cycles, but this correlation in inland areas is vice versa.Existence of alternative drought and wet years that corresponding with sunspot cycles, indicate that, solar activity plays an important role in influencing the precipitation variation in Iran.

In this research, temporal and spatial behavior of Azores high pressure was studied at 700 hPa level. This study has been done using daily data of geopotential height at 12 GMT trom NCEP/NCAR database with spatial resolution of 2.5*2.5 degree in a 55 years period including 20089 days trom January, 1st, 1951(Dey, 11th. 1329) to December. 31st, 2005 (Dey, 10th, 1384). At First, mean geopotential height at 12 GMT is extracted for all days of solar calendar to determine spatial behavior of Azores high pressure and its relation to the contiguous patterns. Then, an agglomerative hierarchical cluster analysis using ward linkage method applied to it. According to this analysis two circulation patterns in the Northern hemisphere were recognized. The first pattern which is coincided with the cold half of year, shows weakening of Azores high pressure and predominance of westerlies with Rossby waves.The second pattern which is coincided with the warm half of year shows maximum activity of Azores high pressure. Occurrence of this pattern is coincided with precipitation cease in most parts of Iran. To identity temporal behavior of Azores high pressure, by selecting a suitable framework, mean of geopotential height whit in this framework at 700 hPa level was calculated and standardized for each day of solar calendar from 1330 to 1384. Thus, a matrix of size 19724*1 was obtained that shows positive and negative anomalies (strengthening and weakening of Azores high pressure) in each day. The mean intensity of Azores index is 0.84 during positive phase and -0.79 during negative phase. Applying contingency table method and calculating X2 statistic during statistical period(1330-1383) showed that occurrence of precipitation in about 4% of studied stations(40 out of 1066) is independent of influence of Azores high pressure. These stations are mainly encompassed southern coast of Caspian sea and North west of Iran. According to this analysis, the occurrence of precipitation in 96% of studied stations (1026 out of 1066) weren't independent of influence of Azores high pressure and are under the control of Azores high pressure at the time of predominance of this system over Iran, intensively.

Temperature is one of the most important environmental factors that affects growth and development of plants. Temperatures above the resistance limit of plants, namely called heat stress, tend to decrease the plants physiological activities. During the ripening period of wheat, when maximum temperature is above 30°C, minimum relative humidity is below 30%, and at the same time wind speed is equal to or more than 3m/s, a kind of heat stress occurs. This weather condition results to a series of adverse effects that tend to decrease yield. When such a set of aforementioned weather conditions occur in one day, that day is said to be critical. The occurrence of such critical situation in southern provinces of the country during ripening period of wheat is probable. Thus in this study using two definitions for critical days, i.e., the frequency and intensity of heat stress, and by analyzing daily data based on the available dates of plant and harvest of wheat crop, findings were examined. Results show that in main regions of wheat planting in Khuzestan province these critical days during sensitive period of wheat crop varies from 3 to 9, and on average, 4 days of that are very critical. In Zahedan and Khash in the province of Sistan and Baluchistan the mean critical days are 5 and 4 respectively. Critical days in Saravan are 12 and in Iranshahr are 6 of which 3 days in Saravan and 2 days in Iranshahr found to be very critical. In Hormozgan province critical days occur only in special years. In cities of Bushehr and Bandar-e-Daier in the province of Bushehr there is only one critical day and that occurs in sensitive period. The results are generalized to same-climate plains.

Traffic crashes are a major cause of human fatalities and their burden, both in social, quality of life and economic terms, create considerable emotional and real costs to society .The severities of these losses are much greater among "developing nations" being several times higher than those in "developed societies". Inter-urban vehicle crashes due to high populated cities in developing regions cause high losses. In developing countries these accidents are mostly caused by insufficient and low standard transport infrastructure and equipment, their poor maintenance and law enforcement shortcomings. Based on increasing dialogue among the world community, there have been signs of increasing interest about developing countries' road safety issues among researchers in developed nations. As there has been little information available with regard to Iran, this paper will be a contribution to the overall understanding of accident costing in developing countries. Inter-urban traffic fatalities in both developed and developing societies are on the top of the list of human-being losses and these accidents are the most important cause of death in the age categories of 15-25. Recent research indicates that in Iran 25 per cent of fatalities amongst this age group are caused by road crash. Transparent road safety funding decisions require an explicit value to be placed on life to allow projects with a range of outcomes in terms of saved lives and reduced injuries to be compared. As the value of lives lost and also the indirect elements of costs are the most important and at the same time the most complicated elements of road crashes' costs, different methods have been proposed for their calculation. The methods described as "willingness to pay", "life insurance" and "implicit evaluations" are frequently employed in developed countries for the calculation of these complicated elements. But these methods are not suitable for developing nations because almost all of them are based on the evaluation of the price of safety in the eyes of people living in a specific society. In developing nations the evaluation of safety prices among people is different "before" and "after" the crash. However in many situations, in these societies, people do not address the right value of safety "before" the incident. Thus, they bargain the safety of themselves and others with cheap prices. Therefore the best method for the calculation of the costs of road crashes in developing countries is not the "willingness to pay" method. The other two methods (gross income and court verdict) will be discussed and used in this study. The "Gross income method" and the subject of "potential years of lives lost" [pYYL] will be also considered.The comprehensive cost of Iran inter-urban motor-vehicle crashes was estimated almost equal to 2.12 billion US dollars in 2003. Comprehensive cost adds the value of lost quality of life to economic costs. This paper estimates costs by injury severity for eighteen severity classification systems. It also estimates the functional capacity loss and probability of permanent work related disability resulting nonfatal injury. In this paper theories for estimation of the cost of road crashes are discussed. Different methods and their relevance to different societies are presented. Then the elements of the cost of road crashes are introduced and estimated for Iran as an example of the developing world. Using only highway costs in safety decision making inappropriately favors mobility over safety. Comprehensive costs are one appropriate choice. Another acceptable choice is to use years of functional capacity loss plus direct costs to perform cost-effectiveness analysis.

Alluvial Fans are manifests of fluvial geomorphology. In Iran these is a clear relation between Alluvial Fans and morphogenetic systems. Iran may divide into four different parts from morphogenetic point of view. Development of Alluvial Fans is somewhat different in every morphogenetic region. In this paper we try to evaluate some geometric and spatial characteristics of major Alluvial Fans of Iran. Meanwhile we will study the relationship between these characteristics and morphogenetic systems.

Geomorphological indicators are useful and confident implements in tectonical activities assessment. Using these indices one can identify regions that experienced rapid or gradual tectonic activities. The study area locates in the middle of Isfahan province. Karkas Mountain is situated in Oroomieh -Dokhtar zone. The orogeny still continues to act in Iran and influence this area. The goal of this study is to assess active tectonic in Karkas slopes. In this study, aerial photographs, landsat ETM data and topographic and geological maps in various scales were used Geomorphological indicators such as mountain front sinuosity , proportion of the valley width to its height, the indicator of stream length -gradient, drainage asymmetry factor have been used to estimate the rate of tectonic activity in the slopes of Karkas. The analysis and investigation of these parameters and indices showed that this area is tectonically active, but theses forces are stronger in the northeast slopes than the southwest slopes.

One of the natural phenomena which results to harmful damages all over the world every year, is the occurrence of severe flood. This phenomenon also occurs in Iran, especially in dry and desert regions. In spite of placing subtropical high pressure centers during some months of year on most parts of country followed by lack of atmospheric precipitations for consecutive months, considerable amount of rainfall can be occur in other months and result to harmful and destructive flood.Yazd province is subject to flood because of its climatic and geographical situation which is located in dry and desert region of central Iran, and incurs great damages in this regard periodically. Therefore, understanding the process, its occurrence and identifying synoptic patterns resulting to flood in this province can be useful in forcasting and reducing the harmful effects of this phenomenon. This research has been conducted using daily precipitation data in Yazd stations, surface and upper levels synoptic maps, also upper atmospheric data in Yazd, Kerman, Shiraz, Esfahan and Bandar Abbas stations during the intended statistical period for 10 selected flood samples. The results of this study show that the presence of cylones for several consecutive days may result in the occurrence of flood to this province. Red sea and Sudan low pressure systems which enter Yazd province through the south western part of the country, if allowed to take sufficient heat and moisture from southern waters, result to flood. Mediterranean- Sudan compound systems which obtain moisture again after passing Zagros possesses severe instability create flood in Yazd province. The intensity of floods depends on the arrangement of synoptic patterns of atmospheric systems.