نشریه جغرافیا و برنامه ریزی محیطی
سال بیست و سوم شماره 1 (پیاپی 45، بهار 1391)

1- Introduction Knowledge as to how climatic extremes are changing, during the instrumental period and the recent period of strong (global-scale) warming, is currently an important scientific goal, as climatic extremes have high environmental and socio-economic impacts. According to Rusticucci and Vargas (2002), the two parameters that mostly affect the human being and their living activities, are the extreme daily temperature values and their persistence, as well. Weather extremes (extremely hot or extremely cold days and nights) have numerous negative effects on natural (plant and animal communities, forest fires, soil erosion, etc.) and human (infrastructure damage, human health, water supply, etc.) systems. Statistical characteristics of extreme temperature events have long been investigated because of their obvious impacts on nature and human. heavy damages are caused by severe winter weather, or by extreme cold weather during the vegetation period. Although worldwide changes in extreme climate events have been detected in the past few decades, various studies have attempted to assess regional level (IPCC, 2001). Climate change-related extreme events at Temperature extremes occur as a result of the interaction between large-scale atmospheric circulation and the local characteristics of a place (for example, topographical features and altitude). To better understand the underlying causes for the occurrence of temperature extreme events, it is important to identify the circulation patterns associated with these events. The objective of this study is to clarify sea level pressure anomalies in extreme cold temperature days of Iran. 2- Methodology In order to studying sea level pressure anomalies in extreme cold temperature days of Iran, temperature data of 663 synoptic and climatic stations during 21/3/1961 to 19/3/2004 has been used. Then temperature on 18*18 kilometer pixels by using Kriging method interpolated for Iran. A matrix that was 15705*5214 has been created. Data of sea level pressure during study period extracted from NCEP/NCAR data site that relevant to United States national oceanic and atmospheric center. At first the extreme cold days recognized with Fumiaki Index and then data arranged according to intense and extend. The first 500 days that were Coldest and most extended selected as sample. In sample days, sea level pressure anomaly calculated. Cluster analysis has been carried out on sea level pressure anomaly in 500 days of extreme cold temperature days of Iran. Then the temperature anomaly for 5214 pixel has been calculated for each pattern. 3- Discussion Cluster analysis of sea level pressure anomaly in 500 days of extreme cold temperature days of Iran shows that four distinctive patterns result in extreme colds. Extreme colds mostly occur in January; almost 29 per cent of extreme colds occur in this month. July experience the least extreme colds. Only the pattern No. 2, that is weak dipole of North Sea- North Russia, occurs mostly in November. Although this pattern exists in 24 per cent of extreme colds, has the least effect on Iran temperature anomaly compared to the other patterns. The pattern of positive anomaly of sea level pressure on North Sea – North Russia mostly occurs in extreme colds. It is seen in almost 30 per cent of extreme colds. The dipole pattern of Atlantic-Scandinavia, while has the least frequency of occurrence, shows 37 per cent of Iran which holds negative temperature anomaly of -6 to -8 c. Pressure anomaly, while this pattern is occurring, reaches at 11 hPa in northeast of Iran. Therefore, effect of this pattern is less than that of pattern No. 1 and more than those of patterns No. 2 and 4. 4- ConclusionThe least occurrence of extreme colds is for summer and especially in July which is 0. 8 per cent of total extreme colds. Roughly speaking, extreme colds are not particular to cold seasons of a year and may occur in warm seasons as well. For all patterns, negative temperature anomaly in south areas of the country and south areas of Caspian Sea is trifling due to the atmosphere humidity.

1- Intro duction Rivers affected by many factors such as geological features, hydrologic, geomorphologic, and how they exploit are subject to change. The most marked effects of changes in direction to channel erosion and lateral movement occurs as meanders. Obviously, unstable bed of a river channel and changes each year, a lot of damage to agricultural land, roads, bridges and generally to enter human structures. On the other hand a considerable amount of sediment to the reservoir of dams to pass. Hence, due to practical purposes the matter goes to the settlements around their homes have always been of interest to researchers. Methods and techniques used in the study centered on two general axes. The first axis of the river hydrological behavior often comes from the river morphometry. The second axis is the study of dynamic behavior in addition morphometry basin characteristics and stream function is morphology. In this study, effective factors in stability and erosion along the river in Lorestan province as a case study with the objectives of the process studied are located lateral erosion. 2- Methodology In this study, to check the instability and erosion of Hor Rood River used aerial photographs (1955) and satellite images IRS (2006) as a comparison tool for Periodical changes. Furthermore, the geometric parameters used for show changes in river morphology and draw, measure, and has been calculated them. In this regard, we used software for calculating the geometric parameters, such as curves radius, the wavelength, the coefficient of curvature, bed width and depth for the river changes direction in the study period. Also sediment samples taken from the river route and analyzed them in laboratory by granulumetry and morphometry methods and then compare with geological maps. the hydrological factors affecting geometrical changes and subscription funds, the path to the river was divided into three specific section. Then the periodical changes of Bed River correlated with the variables studied during a study period and communicate analytical methods and conclusions are given. 3- Discussion Sediment samples taken at intervals of approximately 5 to 6 km from each other from the bed river and laboratory works on them shows that the particle size gradually from upstream to downstream side becomes more fine-grain. This phenomenon is common in rivers sediments. River sediments are generally coarse texture and some branches of the northern part of the main branches in some areas associated with coarse blocks. Transverse profile taken from bed river in three intervals drawn from upstream to downstream. These profiles show the upstream from broad bed change to a low gradient rectangular cross-section with vertical walls relatively high slope to change shapes. These changes do not show any correlation between Sediment condition and dynamics channel. This inconsistent subject formed the main problem of research. 4- Conclusion Geometrical parameters indicate that changes in morphology and lateral erosion from section 1 to section 2 were decreased. But in the third section the bed river is straight and surrounded by river channel and its morphology changes much less than the other sections. Hydrological data also does not shows any correlation with the lateral erosion values of river channel from upstream to downstream. So that with increasing discharge and sediment from section 1 to the third section, the amount of lateral erosion and morphological changes in this direction is reduced. Being reversed results show that the channel morphology of the geological structure and lithology over the river dynamics are influenced.

1- Intro duction Desertification assessment and monitoring studies have focused on providing reliable data and information sources, to underscore the understanding of the causes of desertification, in order to forecast and combat future desertification, as well as to mitigate the effects of on-going processes. Seems whatever has most important in all of desertification studies is selecting, ranking, scoring and preference of desertification indicators to develop desertification indicator systems which is guideline to apply management projects to combat desertification process. Ranking objects is a simple and natural procedure for organizing data. It is often performed by assigning a quality score to each indicator according to its relevance to the problem at hand. Ranking is widely used for indicator selection, when resources are limited and it is necessary to select a subset of most relevant objects for further processing. In real world situations, the object's scores are often calculated from noisy measurements, casting doubt on the ranking reliability. 2- Methodology In this paper have been introduced a Fuzzy-MCDM method for developing desertification indicator system. This paper tries to illustrate TOPSIS method for selection, scoring and preference of desertification indicators. In the first step, were identified the main desertification indicators based on main criteria. Then, to reduce uncertainty a triangular fuzzy set was applied for weighting borders of indicators. Ultimately a Fuzzy TOPSIS algorithm was developed. 3- Discussion According to the applied Fuzzy-TOPSIS algorithm, the anthropogenic parameters such as human activities and land use alternations are main criteria to desertification process. Also to make a risk management pattern, attention to the pressure and state indicators must be notable. Another word, the results indicated the pressure and state indicators as main and high preference indicators for desertification risk management. Results indicated that selection of fuzzy borders can be a reliable way to reduce uncertainty. Also TOPSIS method of decision making is a suitable tool to rank indicators. 4- ConclusionPSIS proved to be a cost-effective and flexible method, as it provides a screening tool to identify, prefer and weight indicators for further investigation. However, this approach is not intended to substitute a scientific analysis of the indicators based on experimental research. After ranking indicators based on expert (and policy) relevance, they have then to be transformed into operational indicators, by conducting field research where necessary, to actually develop and integrate them into structured indicator sets. Furthermore, indicators can be selected and substituted to match the specific characteristics of each region. Since the land degradation conditions are various in different regions, the method can be applied with proper adjustment, provided the principal factors affecting desertification are identified and the relevant data layers are available.

1- Introduction Recently the experts have paid their attentions to tail of frequency distribution of climate elements more than averages, because the changes in these characters have significant effects on intense and continuity of events. So that variations in climate elements could be followed through many qualifications such as extreme events or the tail of statistical distribution. Accordingly the weather extreme events are definite as rare and abnormal events (Bartolin et al 2008: 1752) which are far from the centre of distribution. Due to frequency, continuity and density of the climatic and weather extremes consequences on ecosystems, natural processes (weathering and erosion), and human society and because of their day to day increasing have gotten too much attention. The weather and climate extremes are one of serious challenges in human society during recent century. Accordingly many experts call them “social challenges” and they believe on the economic sustainable developments in providing managing the extremes (WMO 2009). Consequently study the extreme events make us powerful to understanding their tempo-spatial patterns as well as managing them to protect ourselves from negative consequences. 2- Methodology The Extreme analyses in climatology are based on analyses of statistical distributions tails of daily observation of climatic elements. In other words to climatic extreme investigations it has to pay attention to low and height values. So it is necessary to investigate the daily extremes. Accordingly in this research using percentile index to determine extremes as well as absolute values, four extreme indices have been described for Zanjan precipitation during 1961-2006. So that the precipitation equal or less than 5th percentile, precipitation equal or more than 95th percentile, total of maximum precipitation and total precipitation of five greatest precipitations have been calculated for every year as indices of extreme precipitation. Finally the Generalized Extreme Distribution (GED) has been fitted on them. In this research has been attended on the maximum () and minimum () of precipitation time series (), in standpoint of change in distribution shape and its parameters. Accordingly three extreme distributions; Gumbel, Frichit and negative Weibull have been fitted on the data based on thickness, fatness and length of distribution respectively. To finding the distribution parameters it has been used the L-moment method which has introduced by Hosking and Wallis (1997). 3- Discussion irst of all it has introduced the general characters of extreme precipitation in Zanjan. Based on the results of this stage of research it has cleared that low values of precipitation has shown decreasing trends as well as a jump in 1980. The high values of precipitation have shown stationary behaviours in general. Based on testing many distributions on the daily extreme precipitation in order to modelling the tail of probability distribution of extreme precipitation, it has cleared that GED is the best fitted model on the observations. The model has been fitted on four indices (precipitation equal or less than 5th percentile, precipitation equal or more than 95th percentile, total of maximum precipitation and total precipitation of five greatest precipitations) for all time series as well as for two halves of periods (1961-1983 and 1984-2006). The parameter of shape for 5th percentile showed the right skewness. It implicates that low values in this percentile more happened than the heights. This result is true for the second half of the period, but it is not for the first. The first half of the period has left skewness in 5th percentile values of precipitation. So the second half of the period has experienced decrease in precipitation in compare with the first half of period. In addition the scale parameter has shown greatest values in compare with the second and all the time series. All parameters of maximum precipitation for all of the period as well as for the halves of period indicated no significant changes. These results have been achieved for the five greatest precipitation amounts too. 4- Conclusion In this paper in order to investigate the extreme precipitation of Zanjan city, the daily precipitation during 1961-2006 has been analyzed. Accordingly the thresholds of daily extreme precipitation have been definite based on Climate Variability and Predictability Project. In spite of stationary in trend, there have been many non- stationary characters as follow: - There is a 3 year cycle in the greatest 5-day rainfall total - There is a downward jump in the fifth percentile and its ratio to total precipitation since 1980. - The shape parameter of frequency distribution of two parts of fifth percentile of precipitation shows a change in skewness and scale parameter. - There is a similarity but lower change in 95 percentile of precipitation. Accordingly there is a reduction in lower and higher percentiles precipitation in Zanjan.

1- IntroductionThe world is rapidly developing urban life. The rate of urbanization is highly progressing in developing countries compared with that of developed ones. Iran too, has faced urbanization in its rapid pace. This rapid step has with itself so many consequences for large cities specially Tabriz. Hence informal settlement plays fundamental role in reflecting urban studies. The one of problems is slum. The population total Tabriz city 400 thousand individual is informal settlement, that settling in city north, north- west, south and south-west. So that their consequence is appearance of not masons rule types instance urbanization.The employment slum individual in catches undesirable, existence illegal construction, crime increase, cultural, social, economical, environmental pollution is of informal settlement undesirable resulting. 2- MethodologyThe goal of research is analysis of effective factors in creation of slums in Tabriz city, their consequences and presentation of suitable methods for prevention of increase of informal settlement. We invoked survey study along with using libraries. The sampling was elected with the use of Quota. With was done randomly among 322 individual in north of Tabriz. In this research with due attention to society volume and variance calculated research important indices in stage of front test to be used for Cochran method and The data was analysis by SPSS software. 3- Discussion The slum is one world phenomenon, reasons of creation slum is variation that to be possible to differ from place with another place. Migration is them important reasons. Effective factors on slum in Iran to mention social interruption to arise passage for sunna production method with capitalism production, manner of population and employment distribution in country, population many growth and them effective on population growth of metropolitans. In this research for analysis of Effective Factors in Creation of Slums in Tabriz City to produce three hypotheses; that interval of economical attracts of Tabriz city, economical and special repulsive before place have existence meaning connection with slum. The for Experience of hypotheses distributed questionnaires with method of Quota in the middle of slums, and for test of reliability of research questionnaires, with attention with use for specter Likert to be use for method of Cronbach Alpha. The Alpha calculated is for urban economical attracts. 78 percent, for economical repulsive. 71 percent and special repulsive. 79 percent. Alpha calculated to show that question have for many stability. 4- Conclusion The results of this study indicates that main important reasons slum in Tabriz city is unemployment, little income, housing of little rent and widespread migration of small city and village that is arising of economic factors (like economic attractions and obstacles of economic in villages) as well as socio- cultural obstacles related to previous zone. Informal settlement is deniable element in country metropolitans. In contact with this phenomenon must to abstain of unilateral and to effort on serious attempt with goal of science seeking a remedy of this phenomenon is needed. In reality must this phenomenon also to treat medically and also prevention. Than methods of presentation for prevention of informal settlement Select best for Tabriz city is capability.

1- Intro duction Temperature as a hot intensity indicator is one of the main elements for recognizing weather. It is more changeable regard to erratic receiving solar energy by earth that is caused another wide change in other climatology elements (Kamali, 1381). One of the temperature change problem is its untimely vibration, especially temperature drop for freezing point which called frost. Attention to the frost subject is needed, especially in agricultural fields. The occurred frost during 6-15 Jan 2008 in the world was included Iran with drastic cold. This study aims to analyze strict cold at central Iran on 6 to 15 January 2008. In spite of statistical study of this cold period, this study has been analyzed factors of synoptic producing drastic cold. During this period, strict cold affected all of Iran areas regarding central Iran. 2- Methodology There are various criteria for determining glacial intensity that many of them also are empirical. In this research, estimated the glacial severity based on agricultural products types of case study area that is often garden type. Whenever the weather temperature is -10 C and or less called sever glacial. The needed statistical data related to minimum absolute temperature are provided from Meteorological Organization. Earth levels and temp data were provided from NCEP/NCAR databases depend on climatology and oceanography organizations and drawing earth level's maps, 850, 500 and 300 hpa for 1200UTC and 0000 UTC times and omega maps for 850 and 500 hpa in Grads software. In order to subtle studying of this phenomenon, also is used from above atmosphere data and parameters such as frost point temperature, mixture ratio, dry and humid potential temperature for assessment various day's air mass and air variable indicator, (ki, si) also are calculated on this day. For this purpose, it is used to temp data of Yazd synoptic station. The thermodynamic diagram (Skew-T) of cold climax day was drawn by Vayoming University site. 3- Discussion Statistical analyzing of severe cold in January 2008: With studying statistical glacial case 6 to 15 January 2008, it was recognized that this cold and glacial for frost, recording minimum temperature less than -10 C was pervasive in all country and weatherman said that cold with such intensity and widespread was precedence on 30 years ago. In order to study cold intensity in this frost period, minimum air temperature statistic during 6 to 15 January 2008 was used for 5 Kerman and Esfahan stations and 8 Yazd stations. On these regions, phenomenon was rainfall approximately and in many stations during frost days was reported minimum and maximum temperature under zero. In addition to temperature, report of synoptic stations in case study showed the reduction of air pressure for few days before starting frost. For example, on 3th pressure of Yazd synoptic station was 880/5 hpa, that this pressure at next day was raised to 820/4 hpa, i.e., so during 1day was reduced 40 hpa from air pressure. This is influx a strong low- pressure to region and on 5th January again with sudden pressure change. Yazd synoptic station reported the pressure 880/2. Synoptic analyzing of severe cold in January 2008: In order to analyze this cold period, has been drew air maps at 0000UTC and 1200 UTC for various atmosphere levels such as: earth level and 300 and 500 and 850 hpa and Omega maps of climax days. It was required to analyze various atmosphere levels roles from 6 to 15 January 2008. On 7th January was more intensity day during frost in studied areas.. Studying different atmosphere levels shown weather variable. Si variable indicator for Yazd synoptic station was showed number 3 on that day that signified air variable. It was recognized during next day’s also rainfall time, region atmosphere was variable and it was resistant in non-rainfall days together air frost. In 700 hpa level, temperature and mixture ratio were -15 and 1/2 that represented mA air mass. Studying effective synoptic factors in producing Severe Cold Wave on January 2008 which was clouded in all of Iran such as studied areas showed Sybri high-pressure activity and its rotation motions. This system was active more than 10 days on north Iran. Rotation mechanism governed with producing prevented system, which caused cold air over Iran. The maximum reported temperatures in 3 central provinces synoptic stations during frost also was less than 0 degree that showed severe cold wave was an advection frost. 4- Conclusion Synoptic study of this less history cold signified cold air from Russian to country. During snow day and frost, high-pressure was put over Russia on Caspian north and orderly with its rotation motion that was directed cold air across above toward Iran. This stationary air mass were governed over Iran north for 10 days and resistant this order with producing blocking, cold weather moved toward south (Iran) and are caused to cold weather remain over Iran for a long time. Also in many cases, it can be caused, cold north European weather directed toward Iran. Drawing and analyzing Omega maps of frost days has been approved acquired numbers from variable indicators. On other hand, during these days, continuously low- pressures are formed over Mediterranean, Black sea, Africa north, and even Caspian east including Mediterranean and sea black low-pressure. This system with taking humid from water sources such as Red sea, Persian Gulf and Oman Sea caused many rainfall and snow fall in Iran and also case study region. High-pressure both was formed in Arabian and southwest Iran, reinforced this low-pressures and finally caused rainfall and snowfall and making frost throughout country. Also, studies showed that in many central Iran, maximum temperatures not arrived above zero during frost period which showed severe cold wave was an advection frost.

1- Introduction Educational use is one of the most important uses through the physical body of cities and is importance for this issue. The existence of educational use is accounted as an index element through the urban areas (Zarabi et al., 2009:46). Nowadays, with regards to population invasion to big cities and due to construction of whole urban lands and insufficient positioning of municipal services especially in educational centers, several problems have been caused in the field of youth and students services. So, optimal positioning of educational centers is necessary (Mikaeili; 2009: 6). According to the statistics of Fars educational organization within the year 1388, across the city of Kazeroun, there are only 31 schools with 4611 students. Now, the educational space of guidance schools is about 58005 m2 which is accounted as less than as 1percent.. This level of area in comparison with its optimum situation, 99117m2, shows 44112 m2 shortages (Consulting Engineers of Naghshe Mohit, 2009:53). So, the necessity of making new schools across the city of Kazeroun and their proper positioning is felt. 2- Methodology The descriptive- analytical method has been used in this research. All data have been collected by field observations, study of comprehensive models of Kazeroun city and educational organization of this city. Then, proper locations for constructing guidance schools were preceded using the GIS software and after information entry, data management and analysis them. 3- Discussion In this research seven following data layers have been used in order to proper positioning of guidance schools of Kazeroun city; involving proximity to communication network, proximity to urban green space, proximity to residential centers, proximity to cultural centers, distance from available guidance schools, locating across the proper land use, locating on proper slope. Table 1 shows the Rating to information layers according to distance. 4- Conclusion There are several causes in positioning of educational centers (guidance schools), which their different aspect analysis are not been possible by traditional methods. Therefore, geographic information system is necessary for a great deal of information analysis. Also, analytical hierarchy process (AHP) and geographic information system (GIS) have a high efficiency in the field of guidance schools positioning. This efficiency is not related to the comparison and estimation different locations and optimal place selection according to mentioned criteria. After revealing the problems of guidance schools positioning of Kazeroun using GIS,, analytical hierarchy process (AHP) and index overlap model have been used in order to position new guidance school buildings. Ultimately lands which are located in the city limits of the legal and privacy of Kazeroun were leveled and six locations were investigated for new schools. Then, using AHP, these six locations were preceded and best place was detected.