نشریه جغرافیا و مخاطرات محیطی
پیاپی 18 (تابستان 1395)

ZAKERI Gary (1750) found that earthquake is jolts of some places or significant portions of land to natural causes with big voices like thunder that is often accompanied by an eruption of water, fire, smog or wind. After the earthquake, building efficiency greatly reduces because of the network’s collapse and closing of paths. However, after a catastrophic disaster, communication networks play a vital role in saving lives and accelerate the reconstruction and return of the city to normal activities. In the meantime, communicative networks, which are among the bastions of infrastructure, play an important role in increasing or decreasing the damage caused by natural disasters such as an earthquake. Continuing to live in this situation requires the continuation of infrastructure actions and traffic flows for meeting critical needs, the continuity of public services and facilitate urban management. Therefore, if the communication network does not hurt after the earthquake and maintain its efficiency, the earthquake losses will be reduced greatly, because the possibility of escape from dangerous situations and providing access to secure areas and traffic equipment aid vehicles will take place easily.
Studies show that in 2003, according to the United Nations report, Iran was ranked first among countries in the number of earthquakes with a magnitude of 5.5 and had one of the highest rates of vulnerability in the number of people killed in earthquakes. According to the same report, in Iran, earthquake is dominant among natural disasters. Tabriz as the fifth most populous city (Census, 2006) because of being located on seismic zones and several active faults with a history of major earthquakes that had had severe losses has always been faced with the dilemma of natural earthquake. Baghmisheh town is one of the most vulnerable parts of Tabriz in terms of exposure to the vicinity of active faults and two original faults are exactly in the north and south sides of the town. While the designated space for these faults is 2 kms, whole of the town is located within 500 meters of the fault.
Study area: Baghmisheh town is geographically in 38 degrees and 20 minutes of east longitude, 46 degrees and 4 minutes of north longitude, and in terms of urban area, it is located in District five of Tabriz. The town, in terms of vulnerability, has very high earthquake risk and is in the privacy range of fault. This town is the one of the high-density settlements in Tabriz.
Material and In this study, we have tried to use practical and analytical methods to assess the vulnerability of urban passages network against an earthquake. For this reason, Baghmishe town was selected. After reviewing previous studies in this area and seek the views of experts, eight criteria were selected for the study, which consisted of five sub-standards. To use these criteria in the extraction process and overlap on the final map, data should be converted to spatial data. In this context, using the use of field visit data, 1/2000 urban maps, satellite images and other sources, the model map was prepared in GIS support format. Map of structural quality is composed of four maps that include maps of building quality, grading component, the lifecycle of the building and finally IDW interpolation method was used. Data of Tabriz Master Plan and earthquake hazard Micro-Zoning plan that are provided by Tehran Padir Company in the form of GIS maps can be an important source for the study of structural quality, in particular, soil type maps glazed. The next stage of research criteria is standardized by fuzzy TOPSIS model and the importance of each criteria and sub criteria was found. By using analytic functions and commands of Arc GIS 10 Software, final overlay was done based on Fuzzy Topsis for Baghmisheh town passage network vulnerability map that indicates the objectives of the study.
The results of using these criteria in the Baghmisheh town and combining them by using GIS show that the communication network in this town does not have a good position on the earthquake risk (first hypothesis) and more than half of these networks in the area are among the average of the top risk, 6% of networks are in the very high risk area, 22% in high risk, 34% moderate risk, 28% low risk, and 10% very low risk, which represents that this town has twofold importance in terms of seismic and post crisis management because of relatively high population density with according to area and location of the town near the active fault.
Decreasing density and height of building’s walls, using highly resistant structures, devoting semi-public spaces to the buildings, using maximum area in separation crossing wall parts, observing safety course in network design, particularly passage slop, chamfer radius and nodes, observing the proper distance from the center and the right distance from the fault risk are the best practices and recommendations to improve safety and reduce the vulnerability of the city's passage network.

There are about 1500 active volcanoes across the world, among which only about 400 cases have erupted during last century, only one third of which have had recorded historical eruptions. Also, over 10% of world population lives around active and semi-active volcanoes (Tilling, 2005). The majority of hazardous volcanoes are of stratovolcano type. Plio-quaternary stratovolcanoes of Iran are considered as potential volcanic threats in Iran. Hence, it is helpful to evaluate the probability of their reactivation, their kind of threat as well as to determine locations at threat.
Study area: In this regard, we decided to evaluate the hazard aspects of Taftan volcano. Taftan volcano which is 4000 m in height lies at 61°,8ʹ eastern longitude and 28°,36ʹ northern latitude at 45 km north of Khash town in Sistan and Baluchistan province of Iran (Bahrami, Yamani & Alavipanah, 2008). This stratovolcano belongs to the volcanic arc of Makran subduction zone in which the oceanic lithosphere of Oman sea is subducted northward beneath continental lithosphere of eastern Iran and Pakistan (Farhoudi & Karig, 1977). Currently, this volcano exhibits post volcanic activity via sulfataric and fumarolic activities near its summit (Moeinvaziri & Aminsobhani, 1978). Although previously several geological studies have been undertaken on Taftan, but their purpose have been to understand it, so they have not dealt with its hazards and hazard zoning.Since the potassium-Argon and rubidium-strontium dating investigations undertaken by Biabangard (2006) revealed that its latest flows have erupted about 6.95±0.02 thousand years ago, the conclusion is that we deal with a potentially active volcano. Taftan has erupted with strombolian to plinian types of activity in the past (Biabangard & moradian, 2002) and it may erupt with 3-5 intensity on VEI scale in the future. Moreover, it is probable that the eruptions have pyroclastic flows (nuée ardente) or ash (Tephra). Thus, hazard zoning must be conducted for this kind of threat.
Material and After gathering the needed data, Landsat images and digital elevation model (DEM) of the study area were employed to create a 3D model and hill-shaded topographic model to enhance visibility. They also were used to prepare the land use layers of the area. In this study, we employed the VORIS software which is based on advection-diffusion model. In this model several parameters such as height of eruption column (H), the volume of erupting materials (M), eruption duration (D), particle size, velocity and wind direction at different elevations of the atmosphere, air temperature and some other are used. Relevant parameters are needed and were determined for the studied area was introduced to the software and it was run. The output was the ash thickness map (isopach map) (Mastin, 2009).
The contributing factors on tephra movement the air include horizontal velocity of the wind, turbulence and the rate of vertical discendance which vary according the Reynolds number of particles. The atmosphere is divided into several horizontal layers each of them having specific velocity and directions. Ash particles follow the conditions of each atmospheric layer and when entering a new layer are affected by the conditions of this new one. This process continues until the ash particle reaches the ground surface (Mortazavi, Sparks, & Amigo, 2009). The necessary wind data include its direction and velocity in five atmospheric levels (4000, 9000, 16000, 20000 & 35000 m) which in this study were taken from NCEP/NCAR national centers.
In order to determine the route of lava flows from a point (the summit of volcano), the simulation model of lava flow was employed. This model is based on this presumption that topography plays the main role in the route of flows. This model uses two logics, the first one supposes that lava will flow from one cell (pixel) to the nearby pixel whenever their elevation differences are positive, and secondly, the volume of lava entering from one pixel to the other one depends on the value of positive differences between them. In preparing the zoning map with this model, the maximum distance for moving lava was considered to be 5 kms.
The model used for simulating the maximum potential extent affected by pyroclastic density currents (PDC) is a very simple model proposed by Malin and Sheridan (1982). The principle is that the height of the starting point of the flow (Hc) ratios to the length of the run out (L) as a type of friction parameter is termed the Heim coefficient. The inclination of the energy cone is an angle (αc) defined by arctan (Hc/L). The intersection of the energy cone, originating at the eruptive source, with the ground surface defines the distal limits of the flow (Felpeto, 2009). In this study, the collapse equivalent height of nuée ardente was considered to be 200 m and the collapse equivalent angel which is the angel between collapse height and slope angel was presumed to be 6°.
According to this study, Taftan is a potentially semi-active volcano which may reactive in the future. It has erupted lava flows, tephras and nuée ardentes in the past. According to the presented hazard zonation map, the flows and nuée ardentes threats some nearby villages. The ashes will disperse and extend eastward and will rise and accumulate in some villages. It is suggested that a seismological station be established near this volcano for forecasting its probable eruptions. The kind of threats identified and the hazard zoning maps may be used for emergency evacuation and hazard reduction programs.

The Earth's crust is composed of various landforms. These forms are constantly changing. In this change, both of internal and external factors have a decisive role. The Internal factors led to the formation of the primary structure and external factors that cause erosion, deformation and destruction of these forms. Areas that have been affected by these activities confronted by various geomorphological forms, the alluvial fans were formed by different causes in this highlands. This study is an attempt to study the influence of tectonic on the formation and development of alluvial fans in the northwestern slopes of Sahand, calculate the seismic generating power of faults, and evaluate the seismic zoning of the risk arising from fault position on the alluvial fans and human activities. Sahand Mountain is located in the northwestern Iran with a geographical coordination of 37°07'to 38°02' North and 45°53' to 47°00' East. The total area of alluvial fans is 29.874297 square kilometers. This massive mountainous acreage covers an area of 8,000 square kilometers.
Material and In this study, 1: 25,000 maps of National Cartographic Center were used as the basic maps to identify tophographical units and location of alluvial fans. The geological map of 1: 100,000 were used to identify faults and geological formations of the region. Aerial photos of 1: 50,000, 1: 40000.1: 20000, from this area as well as satellite images were used in the completion of studies. After identifying alluvial fans and their initial review of the documents, the seismic data of the area was collected. Fault zones were detected by studying available geological maps, and their most important ones were drawn to the field of satellite imagery. Then, the seismic characteristics of the region were analyzed and a list of earthquakes were collected in radial expansion of 300 kilometers .The seismic potential of active faults from the initial parameters related to earthquake risk assessment were calculated using zarei, Ashjaei and Navrozi's formulas.
The impact of tectonic activity in the form of alluvial fans were analyzed by these indicators: the effects of tectonic on alluvial fans using the index Vf ; calculation of Vf on the alluvial fans of the area shows that only two alluvial fans (6 and 7) of the index are between 1-2 and other alluvial fans index are smaller than 1. The effects of tectonics on alluvial fans using the curvature index: the results of the study show that the alluvial fans of numbers 2, 3, 5, 9 have the smallest curvature coefficient and alluvial fans 6, 7 and 10 have gained the largest amount of curvature coefficient.
According to the results of this study that indicates tectonic activity status (fault) on the surface of the alluvial fans, high seismic potential of faults represent a high risk arising activity of faults in the surface of alluvial fans. Hence, any activity in the alluvial fans (build settlements, communication lines, construction projects, etc.) needs preparation and special considerations so that the losses of the operation can be reduced to a minimum. Values obtained indicate that the role of tectonic activity in the region has been higher on the alluvial fan because of the proximity of the large faults in the studied area. 2 faults in the region have the highest longitude. The risk of these faults are threatening Tabriz and Khosrowshahr cities with widespread devastation.

Wind erosion is a major Geomorphological force, especially in arid and semi-arid regions. It is also a major source of land degradation, evaporation, desertification, harmful airborne dust, and crop damage especially after being increased far above natural rates by human activities such as deforestation, urbanization, and agriculture. Wind erosion removes sediment, damage crops, fences, buildings, and highways. Fine sediment particles are lost along with nutrients, which can result in reduced crop yield. Eroded sediment particles are a nuisance for many people and can adversely affect the health of some individuals. There are also circumstances where eroded dust can obscure visibility. Such conditions can lead to fatal traffic accidents. Above 80 percent of Iran is currently located in arid and semi-arid to dry and sub-humid climates and they have sensitive conditions given the climatic conditions and natural characteristics of these regions and improper utilization methods, hence, they are potentially and actually subject to the phenomenon of desertification. The central and southeastern parts of Iran are always under the influence of wind hazards due to their location in arid and semi-arid regions of the world and existence of sand areas. This process each year makes damage to the rural housing in the area. The running sands have great influences on the settlements and facilities. The roads and transportation facilities are greatly affected by the hazards. The networks play an important role in making relations between neighboring villages as well as passenger and cargoes transportation. These networks are sometimes disrupted by the sand masses.
Study area: The Lut Desert is located in the south-east of the country. Between June and October, this arid subtropical area is swept by strong winds, which transport sediment and cause Aeolian erosion on a colossal scale. Consequently, the site presents some of the most spectacular examples of Aeolian yardang landform. It also contains extensive stony deserts and dune fields. The property represents an exceptional example of ongoing geological processes. The study area of this research is located in east Kerman and west part of Lut Desert. It is located in from 57:52:15 E to 57:53:15 E longitude and from 32:27:00 N to 32:28:00 N latitude at 298 meters above sea level. This area is in Takab of Kerman County near Hojatabad and Islamabad. There are vast sand areas in the vicinity of the area. The average precipitation in the Shahdad Station is 35 mm and most of the rainfall is in winter. The average temperature is 40 C and the average of Maximum temperature is 46 C in July and the average of minimum is 34 C in December.
Material and This is a descriptive analytical research in a survey. The research is carried out in two quantitative and documentary parts. In documentary section, we have used library and literature review, and in quantitative part we have also used statistical data to make required maps. In the method of this study, we initially found vulnerable villages and the areas susceptible to the sand movements. The villages have been observed in the field and then their border has also been specified on the map. How the villages are affected by ted sand have been determined to find the vulnerable parts of the rural areas. The most important parameters affecting the sand movement have been identified and entered into ArcGIS software. Fuzzifications have been made on the layers and they have been prioritized by Fuller Triangle. In the next stage, the villages have been ranked in their vulnerability using Oreste model.
The ranking of the villages have indicated that some villages are more affected by the sands and some others are less influenced. The villages in southeast part are more affected due to more severe winds, less ground water level, and less soil thickness. The villages of Deh Ghazi and Zaman Abad are in the 1st and 2nd ranks, respectively. The villages in northwest are less influenced by the sands due to more ground water level, less wind severity, and more surface water. The villages of Shojaabad, Dehnosalar, and Salarabad are, in order, less affected by the sands.
The results of the research have indicated that the villages located in the southeast part are more affected by the sands and that the cultivated areas, roads, and facilities in these areas are more threatened by the sand effects. On the other hand, the villages in northwest including Shjabadmohamadali, Deh no salar and Salarabad due to the parameters listed better than elsewhere in the region is less affected. Generally, natural factors can influence these rural areas differently.

Forest fire is considered as a natural disaster and a major potential threat in many parts of the world. It also has a huge impact on the form and compounds of different species and the spatial pattern of plant coverage. Fires in forests and pastures are one of the world's most important issues, not only environmentally, but also from an economic and social aspect. Forest fires usually result in the destruction of the forest or its renewal which is of different importance in different regions regarding its destruction and the amount of damages it brings about, because its severity depends on the climate of the region in which it occurs. Forest fire is a primary process which also affects botanicals and their spatial structure. The emitted smoke from forest fires is amongst the most worrying consequences of this phenomenon. Fires have a large impact on the quality of air and human health, because they release large amounts of compounds such as carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), nitrous oxide (NOX), ammonia ( NH3), particulate matter (PM), non-methane hydrocarbons (NMHC) and other chemicals in the atmosphere. On the other hand, as a result of forest fires, the soil loses a large degree of its organic materials, the risk of soil drifting increases and it also has significant negative impacts on the regeneration of previous species and the environmental conditions. Many physical, chemical, mineralogical and biological features of the soil are changed as a result of the forest fires. Due to the fact that Iran is at a critical condition with regard to its forest ecosystem and this ecosystem has experienced huge fires on an annual basis, the necessary measures should be taken to identify the causes of forest fires and prevent them if possible.
Study area: The city of Dezful is located at the plain areas of Khuzestan province, Iran, with an area of 7844 km. This city has expanded at the geographical longitude of 48 ° and 24 minutes east and latitude of 32 ° and 22 minutes north and its height is 140 meters above the sea level. Like most cities in Khuzestan, Dezful has a warm and humid climate with hot summers and Mediterranean winters. The annual average precipitation in Dezful is 250 mm and its average temperature is 3° C in winter and 49 ° C in summer.
Material and In this study, two sets of data were used to analyze the fire at Dezful’s forests. First, the statistics regarding the fires were received from the department of forest and rangelands and in order to synoptically analyze this phenomenon, the data from the upper levels of atmosphere were taken into consideration. Based on a report submitted on 12.05.2012 and 08.01.2012 (23rd Ordibehesht and 11th Mordad 1391 in the Iranian calendar), two of the fiercest forest fires of 2012 in Iran have occurred in Dez and Dezful national parks which have resulted in 700 and 270 million Tomans damage to the forests and natural rangelands of Khuzestan Province, respectively. In order to analyze this damaging risk from an atmospheric point of view, the induced data of the components of sea level pressure, geopotential height, orbital and meridional wind at 2 meters above the ground and the upper levels of atmosphere, the temperature of different levels of the atmosphere and 2 meters above the ground and the relative humidity which were taken from the website of the National Center for Environmental Prediction (NCEP) were used. The maps which have been drawn and analyzed for the atmospheric analysis of forest fires in Dezful include the maps of sea level pressure, geopotential height, the thickness of the atmosphere, wind direction, atmospheric temperature, vorticity, thermal wind and relative humidity. The maps were analyzed at the following levels: temperature maps at the levels of 850, 925, 1000 HP and maps at 2 meters above the ground, maps of geopotential heights and wind currents at different levels (500, 600, 700 and 850 HP), vorticity maps at the levels of 1000, 925, 850, 700, 600 and 500 HP, thermal wind map at the levels of 1000, 925, 850 HP, wind and thermal wind at 2 meters above the ground, and relative humidity map at the levels of 1000, 925, 850, 700, 600 and 500 HP. All the maps were developed at the latitude of 15-70 and longitude of 10-75 and the time for drawing the maps was selected to be 12 Zulu time which is equivalent to 3:30 P.M. local time because of the higher visibility of the phenomenon under study.
Discussion and Findings: The analysis of atmospheric maps indicated that at the time of occurrence of fires in thermal forests, the blocking phenomenon associated with a stack on the study area on the 12th of May and very high contours on the 1st of August were observed.The thickness of the atmosphere which is a sign of the establishment of a hot system, hot thermal wind above the region with the dominance of thermal conditions and temperature of above 40 ° C on the 12th of May and the temperature above 48 ° C on the 1st of August are amongst the other dominant atmospheric patterns these days. Atmosphere stability and negative vorticity flow which has been followed by the subsidence of the warm air flow of southern latitudes from upper levels to the ground level together with very low relative humidity (10%), which has imposed a dry atmosphere on the climate of Dezful, have prepared the necessary conditions for the occurrence of fire at the forests of Dezful.
Based on what has been stated so far, the establishment of thermal units at ground level, occurrence of blocking at the upper levels of the atmosphere and the deployment of high contours and stacks on the studied area, thickness of the atmosphere and hot thermal wind above the region with the dominance of thermal conditions and a high temperature alongside atmosphere stability and negative vorticity flow which has resulted in the subsidence of the warm air flow of southern latitudes from upper levels to the ground level together with very low relative humidity (10%) which has imposed a dry atmosphere on the climate of Dezful, have provided the necessary conditions for the occurrence of fire at the forests of Dezful. Since no study has to date investigated the thermodynamic causes of fire at the forests of the southwest of Iran and researchers have just examined the causes of this phenomenon in the northern forests of Iran, the results obtained from previous studies have similarities and conflicts with the findings of the current study. Regarding the fires which occur at the northern forests of Iran, Foehn wind is very important and flows at the high pressure ground level, while at the time of fire in the forests of Dezful, this type of wind was very important at the low pressure ground with a high pressure of central core. However, the commonality of both studies is high temperature,the relative humidity of less than 20%, the position in height, and the stack at the upper levels of the atmosphere which is observed in both the environments. In this study, some parameters have been investigated which have not been considered at all in other related studies.

Mountains are the main sources of turbulence and change in the shape of atmospheric flows, and they can cause airflow upward as well as clouds formation and rain through productive mechanisms such as upslope condensation and convection. They also have an important effect on regional and world precipitation turbulence (Banta, 1990; Barros & Lettenmaier, 1994), and can cause severe incidents such as destructive floods (Pastor, Gomez, & Estrella, 2010).
Previous researchers have done numerous studies on mountainous region weather and climate, and cause of precipitation phenomenon using different methods such as numerical modeling of airflow and satellite images. Using RegCM model, Insel, Christopher, Poulsen and Ehlers (2009) have studied the effect of Andes Mountains on convection, precipitation and humidity transformation in South America. They showed that Andes Mountains have lots of effects on humidity transfer between Amazon basin and central Andes, deep convention processes and precipitation across South America through low–level jet (LLJ) and topographical blocking from Pacific Ocean.
Zagros mountain range located in west of Iran plateau is among vast mountain ranges that locates in path of zonory flows with its south-north expansion and can affect those flows.
Therefore, the present study aims to investigate different factors affecting mesoscal convective systems from Zagros heights, and analyze their life cycle dynamic conditions using brightness temperature threshold, area expansion and RegCM4 numerical modeling.
Material and This study was done in an area of about 220000 km2 in west of Iran including Kermanshah, Kurdistan, Hamadan, Khuzestan, Lorestan, Kohgiloyeh and Boyer Ahmad, Ilam, and cheharmahal and Bakhtiari provinces. Using satellite images obtained from infrared band of Meteosat geostationary satellite, GOES and GMS, the mesoscal convective systems and their life cycle were identified.
Regarding that Inoue, Vila, Rajendran, Hhamada, Wu and Machado (2009) proved if we use one colder or warmer threshold, both initiation and dissipation phases may not indicate the life cycle, in this study, brightness temperature threshold of 224 K (Volasco & Fritsch, 1987) and 243 K (Machado, 1998) were used for identifying and analyzing systems life cycle. The researchers have tried to choose some days for this study over which mesoscal convective systems have been made and spent their life cycle without merger or split.
By transfering these systems to GIS environment using area expansion index (∆E) whose validation and viability have been confirmed by Vila, Machado, Laurent, and Velasco (2008) its life cycle was verified (eq. 1).
∆E=(1 δA)/(A δt) (1)
A = the system area in a given time (Tir

The meaning of sustainability is an effort to reach the best results in human and environmental programs which are considered to be for present and future. Zayandeh-Rud is the most important and vital river in Esfahan Area which is used in agriculture, industry, providing drinking water and all other economic sectors. This river is originated from the Zagros Mountains – Zardkooh Bakhtyari – and ends in Gav Khooni wetland. Following the development of human settlements (namely human and agricultural structures) and developing new water resources for different purposes many alterations have happened in the natural environment. These changes have caused a change in the use of the land in this natural area and also have negatively affected the sustainability of the environment. This research will investigate the environmental consequences of the development of human residences in Zayandeh-Rud Basin, from 2002 to 2013. Land use alterations with distinct divisions in two periods in 2002 and 2013, with considering the basin in 3 sectors (upper, middle, lower) are analyzed. Based on this research finding, human settlements both in terms of residential or agricultural (farming and forest) use have been developed in different parts and many original lands and farms in the Basin have been used by human activities. The raw data in this article has been used from the land use map by “National Forest and Land Organization”. The data have been gathered in 2002 and 2013 and the experts’ views are used in doing and finishing this research.
Study area: Zayandeh-rud River is a vitally important river for agricultural developments as well as domestic water supply and economic activity in west-central of Iran. It is a completely closed basin having no outlet to the sea. The river is about 350 kilometers long and runs in a roughly west–east direction, originates from Zagros Mountains, west of the city of Isfahan, and terminates in Gavkhooni wetland to the east of the city. The Zayandeh-rud contains more water than any other river in central Iran. The Zayandeh-Rud River originates from Zagros Mountains (4500 meters higher than the sea level) which is located in the most western parts and flows in a west to east orientation to the Iran’s central plain and finally ends in the most final point of the Basin in Gaav Khooni marsh. The length of river is 350 kilometer and area of basin is about 41500 Square kilometers. The Zayandeh-Rud river basin, in central Iran has a semi-arid climate and large agricultural, industrial, and domestic water uses. The Zayandeh-Rud basin with 26917 kilometers width is located in Gaav Khooni marsh basin in central desert of Iran. Zayandeh-Rud basin is limited from north to Salt Lake Basin, from western and western south to Karoon and Dez basins, from east to Daghe Sorkh and Siah Kooh desert basins, and from south to Shahreza basin. The climate of this basin is varies a lot. Whereas Chehelgerd area in west of basin has more than 1400 millimeters rainfall, in the east of basin near Gaav Khooni marsh is less than 100 millimeters. From 26917 kilometers area of Zayandeh-Rud basin, %93 is located in Esfahan and %7 is located in Chaharmahal and Bakhtiari Province. Population of the basin in 2006 was 3668000. About %98 are in Isfahan province and %2 resides in Chaharmahal and Bakhtiari Province.
In this research two methods are used, library research (book, papers, basic data collected from “National Forest and Land Organization”) and field research (observation, and interview with experts). All the basic data of this research are based on “Land Use National Plan” from the “National Forest and Land Organization”. In addition, the experts’ views were used in all the phases of the research. Having used ETM images and field work, “National Forest and Land Organization of Iran” created land use map of whole of Iran. These maps were made between 2002 and 2013 and confirmed officially. The study target in this research is Zayandeh-Rud River Basin. Border of study area was specified with spot goals of research and views of experts. Then this border was mapped in “Google Earth” and the study area's border of research was extracted from basic map of National Forest and Land Organization of Iran”. Study area of research was divided into three section as follows, The upper section is from Zayandeh-Rud river springs to Cham- Aseman dam, the middle one is between Cham- Aseman dam to Limit of Isfahan city in east middle of Baraan plain and thee lower section is from middle of Baraan plain in east of Isfahan to the end of Gaav Khooni marsh. Land use alterations are analyzed with distinct divisions in two periods in 2002 and 2013, with considering the basin in three sectors (upper, middle, lower). Land use basic map in “National Forest and Land Organization” had twenty-two items that were merged and reduced to nine land-users. Change detection was done in Arc GIS software using Union program and exhibited the map, table and descriptive information.
The comparison of land use map in 2002 and 2013 of total of study basin indicates that dry farming, agriculture, forest, residential settlements and marsh land uses have increased while water surface, canebrake, and deserts as well as rangelands have decreased. In the upper section, explosion of human settlements and revolt of nature in the recent decade have increased. Human land use such as agriculture and farming and human settlements increased to 140258 hectares and water surface and canebrake, deserts and Rangelands land use decreased to 141262 hectares. In the middle section, because of human density and spread of human settlements, whole of land use increased and only desert land use decreased. In lower section, farming (agriculture) land use, forest, marsh land, residential settlements and dry farming increased while Rangelands, desert, water surface & Canebrake and plantation forests decreased.
The results of the study indicate that spreading of human settlements in Zayandeh-Rud river basin altered all of the land use and influenced environmental sustainability. In this time (2002-2013), desert, rangelands and water surface & canebrake land use decreased while farming (agriculture) land use, forest, residential settlements and dry farming increased. Land use changes occur in all parts of Zayandeh-Rud river basin, but, most of variation happened in the upper section of area. This area includes Zayandeh-Rud river springs in Isfahan and Chahar-mahal and Bakhtiari province to Cham- Aseman dam, between Zayandeh-Rud dam and Isfahan city. With this process of spreading of human settlements without spotting the capacity of environment and nature, we will face with the destruction of environment and ecological in future. This process of development is dangerous for human and environmental sustainability in Zayandeh-Rud river basin. The development of the human residence and overuse of the natural resources bring about the destruction of nature and the natural ecosystem. Misbalancing the ecosystem in such a short time has misbalanced the sustainability of water resources and plant, animal and human ecology has been negatively affected, too. Considering all of these factors, the continuity of developing of the residences and the alteration of the land use will heavily damage the sustainability of the environment in Zayande Rood Basin.

Thunderstorms or lightning storms are kinds of storms that generally are associated with the convective clouds and usually are resulted in hailing, strong winds, and flash floods. Clouds of convective storms are observed in most regions, but a small percentage of the convective storms can produce severe weather conditions and flash floods that cause damages. A flash flood is a dangerous inundation that occurs over a few hours or less, and is caused by heavy rainfall over a small area. This flood is one of the most common types of hazards produced by convective storms, which are difficult to predict. This is mainly because such severe storms are local events and they usually affect smaller areas compared to tropical cyclones. Basically, vertical movements in the atmosphere are the key of most characteristics of convective systems. Hence, conditions leading to the development of deep convection and resulting in severe weather events (e.g., flash floods, hail etc.) are characterized generally by unstable air, high moisture at low and mid-level, and the force which stimulates convection. This force may be caused, for example, by ground heating, orography, convergence,atmospheric front, jet stream and the like, although the synoptic patterns provide favorable conditions for the development of storms.Thus, to study the convective storms, synoptic and thermodynamic conditions, humidity and similar conditions should be examined.One of these deadly thunderstorms which occurred on June 19, 2015 was a great human and financial loss. This storm killed around 20 people and financial losses were huge.In this study, the synoptic and thermodynamic conditions of this thunderstorm are discussed. The aims of this study are to predict the likelihood of thunderstorm occurrence, determine the extent of possible storms and the location of the convective storm and its relationship with the synoptic systems.
Study area: The study area is located between the northern latitude of 35° and 07 minutes to 37° and 06 minutes, and the eastern longitude of 48° and 40 minutes to 51° and 34 minutes. This area includes parts of the provinces of Tehran, Qazvin, Zanjan, Gilan, and Alborz provinces. This area includes the southern slopes of the Alborz Mountains and the plains leading to these slopes.
Material and Previous studies in thunderstorm distribution have emphasized that the synoptic patterns provide suitable conditions in which thunderstorms can develop easily. Thus using the NCEP/NCAR data, synoptic conditions in the middle and lower levels of atmosphere such as sea level pressure, geopotential height, Omega, moisture convergence, specific humidity, wind pattern and precipitable water were investigated.
Fundamental to the understanding of severe weather and flash floods is how wind, temperature and moisture vary from the surface to the top of the troposphere. Some indexes have been introduced to calculate these variations which are called the instability index.Whatever is very important, the instability of the atmosphere can be determined several hours before the beginning of convection.Hence, Skew-t diagram and upper air data were used to determine instability with instability indexes. Some of the important instability indexes areCAPE, KO, MVV, JI, TI, TQ, VGP,VT,SI, K, LI, TT and SWEATthat we used in this study to estimate the instability of the atmosphere. Theseindexes were calculated withRAOB software.Then,the intensity and probability of thunderstorm occurrence were determined.
The occurrence of thunderstorm-related severe weather (flash floods, hail, etc.) is highly correlated with the intensity of convection. Using IR data one should be able to calculate parameters related to convection intensity, such as cloud top temperature.Therefore, with the calculation of brightness temperature, the vertical and horizontal extent of convective clouds was determined and their relationships with synoptic systems were examined in GIS software.
The results showed that the favorable synoptic conditions for thunderstorm occurrence, including low pressure at sea level and mid level, moisture convergence and sufficient moisture in the lower layers of troposphere were available in this day.The precipitable water on this day has been 30.29 mm that is sufficient to produce flash floods in unstable atmosphere.
Results of instability indices showed that KO, KI, JI and VT predicted stronginstability and severe convective storms. Six indexes of CT, LI, SI, TQ, TT and VGP predicted moderate instability (convective storms) and two indexes (SWEAT Index and CAPE) predicted weak instability. RAOB Software predicted that maximum vertical speed reaches to 30 m/swhich indicated sharp rise and severe thunderstorm.These results are for the 00 GMT.
Satellite image processing for cloud top temperatureindicated that several areas have deep convective clouds. These areas are in Kordestan, East Azerbaijan, Zanjan, Guilan, Qazvin, Tehran, Alborz and Semnan Provinces where cloud top temperaturesare below 240 degrees Kelvin. The main core of the storm was between Karaj and Qazvin and it matched with the maximum negative Omega at 500 hPa. Cloud top temperature at this core had been below 230 degrees Kelvin and it had considerable horizontal extension.Vertical extension of storm (based on cloud top temperature) between Alborz and Qazvin had been about 12 kms that confirms the results of instability indexes and synoptic conditions. These results are for the 12:50 GMT. Hence, these results verified that the probability of the severe thunderstorm occurrence has been predictable several hours before beginning in the area.
Although there is wide agreement that all thunderstorms require warm and moist air (as the prime gradients leading to the formation of thunderstorm) in the atmosphere, other suitable conditions are needed to increase instability and, as a result, to initiate convective activity. The roles that may be played by atmospheric instability are very important factors in thunderstorm development. In this case, the favorable synoptic conditions for thunderstorm occurrence, including low pressure at sea level and mid level, moisture convergence and sufficient moisture in the lower layers of troposphere were available. In additionto using instability indexes, the likelihood and severity of storm estimated several hours before occurrence.Some instability indexes predicted strong instability and severe convective storms in study area and some others predicted moderate instability. The result of the preview on synoptic pattern and instability indexes proved that synoptic condition and instability were suitable for thunderstorm occurrence. Thus, accompanying suitable thermodynamic and synoptic conditions can lead to the severe convective storms.
Results of satellite image processing indicated that cloud top temperature is a good representative of convective storms. The minimum cloud top temperature is correlated with report of severe weather on the ground.In this case, the cloud top temperature reached less than 230 degrees Kelvin and according to the thermal profile of Mehrabad station, the storm had spread 12 Km far away.The minimum cloud top temperature that located between Alborz and Qazvin, matched with minimum of Omega at 500 hPa.

Although solar energy is one of the important renewable, free and clean energy sources, constant exposure to the sun, especially UV radiation, can lead to some problems. These problems include skin diseases, loss of pregnancy, permanent or temporary infertility, and cataracts (Strom, 2003), weak immunity system, and an increased risk of diseases especially in children (Hoyos-Bachiloglu, 2014). Cofounding variables such as age, gender, history of diabetes and also, the location of city increase the risk of cataract by 33% (Nakashima, 2010). Exposure to different qualities of radiation can result in premature diseases impairing the diagnostic power of eye lens cells (Blakely, 2010). Increased sensitivity to visible light could be determined by the total accumulated dose of radiation during activities (Tremsin, 2001). Many studies have shown that both PSC and cortical opacities are associated with radiation exposure (Blakely et al.,2010). Cortical cataract has a stronger correlation with exposure to UVR than PSC Cataract (Kanamoto, 2010). Chronic exposure to UVR in an interval of three days can lead to promotion of the vulnerability to the eye, but if this time is increased to 30 days, the risk of eye injury is decreased due to the repair of the damaged part (Midelfart, 2010). PSC and cortical cataract have a stronger correlation with a low dose of space radiation in astronauts, in comparison with the nuclear cataract (Chylack, 2010). Visual impairment diseases are prevalent in Chaharmahal and Bakhtiari province. There are 1912 people with various forms of eye diseases. Among these, 900 live in rural areas. This study aimed to study the effect of physiographic features and climatic factors on the prevalence of blindness and visual impairment in some rural regions. Study Area: The villages of Chaharmahal and Bakhtiari province.
Material and In this study, three sets of data were used: 1. Data on the amount of emission radiation and other climatic factors such as sunshine in all stations.
2. The data on visual impairment in 189 rural areas.
3. Digital File DEM map of Chaharmahal and Bakhtiari province in the scale of 1:25000 was used to estimate the basis of measurement and the slope in the village's location and climatic parameters.
As the amount of radiation in village location depends on such morphological factors as slope and its orientation and the location of the village, the radiation of the villages was estimated based on village morphological characteristics, using Duffy and Beckman's (1980) method. Because the slope has a significant impact on the intensity of the radiation received at the earth's surface, the amount of it and the village's slope were calculated based on the topographic map of the province. The villages slope was calculated by the raster map of digital elevation model (DEM) in the scale of 1:25000.
There were 900 blind people in the rural centers, with 547 cases in 57 villages. The percentage in 57 villages was 60.7%, including 30.2% percent of total villages. The highest number was in the south, south east and south west with 256 patients (46.8%) and 45.6% of villages, west and east, with 141 patients (25.8%), and the north, north west and north east, with 150 cases (27.4%), respectively (table 1). The correlation between the slope and the rate of blindness, with R=0.373, was significant. The correlations between slope azimuth to the south and the amount of radiation on slope, and the percentage of increase in the amount of radiation and the slope were R=0.820 and R=0.795, respectively. The village of Sar Aqa Seyyed with high blindness (13.2 in thousands) had a great slope. Sheikh Ali Khan with the highest rate of blindness (49.02 in thousands) also had a southwest slope, which was 14.6 degrees.
Evaluation of the elevation of the villages showed that all these 57 villages were at altitudes above 1170 meters, and the village of Sheikh Ali Khan with the highest rate of blindness was located at an altitude of 2499 meters above sea level. Of the 57 villages, 30 villages with 333 cases of blindness (60%) were at an altitude higher than 2000 meters, 20 villages with 173 cases (31.2 percent) were at an altitude of 1,500 to 2,000 meters, and just 7 villages with 49 cases (8/8 percent) were at an altitude of 1500-1170 meters. In villages with a greater slope, the difference between the red and blue lines was greater. The highest percentage of increase in intensity was in the slopes of the south and south west and south east. Generally, the amount of radiation on the slope level was increased by 3.5 percent in all villages. The correlation coefficient between the amount of radiation on the slope level and the percentage of the increase of radiation in the slope level was 0.892.
Solar radiation increases the epidemic risk of eye diseases such as cataracts. Mountain and high altitudes of Chaharmahal and Bakhtiari province villages made up the sunshine on slopes facing south, south west and the south east. Our study showed that 45.9% of the rural population and 42.1% of villages with a high risk of cataract were in the facing slopes to south and south west and south east. There was a significant relationship between the slope and slope orientation to the south and the rate of blindness. Therefore, by increasing the slope and changing slope to the south, the number of cases of blindness was raised in the villages. There was also a significant association between increased height and the increase in the number of villages with blindness and more cases of blindness (60%) lived at an altitude higher than 2,000 meters. Because of rise in the highland villages, the height of the atmosphere would be shorter with thinner radiation. There can be, therefore, environmental changes to improve the villages’ microclimatic conditions and reduce the risk of eye disease. For example, by increasing the relative humidity, the sun intensity could be reduced. Environmental changes can improve the village microclimatic conditions and reduce the risk of eye disease. Thus, by increasing the relative humidity, the air temperature would be reduced; the brightness and intensity of the sun could be reduced and hence, the risk of eye disease would be decreased. Better decisions can be them made to change the location or reform the physiographic features of villages needs based on further studies.