مجله مخاطرات محیط طبیعی
پیاپی 15 (بهار 1397)

Flood can be having devastating effects on watersheds and human life, so, recognize of flood prone areas have a high influences on flood management. The aim of this study is to assessment of flood susceptibility at Talar watershed with an area of 2067 square kilometers. For this purpose some flood conditioning factor such as elevation, land slope, curvature, topographic wetness index, stream power index, average rainfall, distance to the river, hydrologic group of soil, maximum depth of soil, and land-use have been used. Flood conditioning factor have been prepared using related software and then converted to raster format. In the next step the 135 flood location in the study area were determined. These flood location were divided into two groups consisting of 93 locations for calibration and 42 locations, for validation. Then with comparatively analysis between previous floods coordinates and impressive environmental parameters on flood occurrence the probability of flooding for each class of each parameter was calculated. Faunally was obtained the flood risk map of the study area. Based on the flood risk map, the territory was divided to 5 class sensitivity, very high, high, medium, low and very little. The results have been showed that the frequency ratio method with 80% accuracy have high performance in determination of flood prone areas in Talar watershed.

Across the globe, floods have posed a tremendous danger to people's lives and properties and have had a great impact on human development, properties, infrastructures as well as environment. In the paper, we have investigated Qaresou River to the end of reducing, mitigating and management of floods with providing of zoning map using Fuzzy Logic in ArcGIS Environment. For studying the river, we have used parameters such as slope, elevation, a distance of channel, drainage density, land use, lithology, precipitation, profile curvature and planimetric curvature. To provide data and layers we have used DEM, topographical maps(1:50000), geological map(1:100000), land use map of Kermanshah province, a satellite image of Landsat(ETM) and the image IRS- LISS III. The methodology of the research is fuzzy logic in GIS environment to provide zoning map. Results show that the Gama of 0/7 is the best operator for zoning the region. According to the map, the high-risk segment contains 24 percent of the region that has located in the north of the river and the south as well, where Kermanshah city has located. Thus. With a distance of the river in the high elevation and slope, the rate of risk of floods reduce. Results show that the most effect area (in floods map) is located between slope 0-5 degree, elevation 1240-1250m, the group of hydrological soils D, Drainage basin 0/4-1, precipitation 650-750mm, Planimetric profile 0/6, the land use of urban and distance of 500-1500 m of the river.

In this research in order to identify the most effective jet stream pattern, creating pervasive rain falls in Iran during the period 1971 to 2008, from turning approach to the environmental approach was used. For this purpose, first of all, an elemental analysis with component based approach on wind speed data with the balance of 300 HP for 12 of Zolo was done by demystified data of United States of America Atmospheric Prediction Center. The analysis showed that 8 main components are able to explain 85% of the diffraction of data. Then, by applying a hierarchical cluster analysis with Ward's method on the scores 8, mentioned component during the 3098 days under study, eight prevailing jet stream was detected on Iran. Then for every pattern, using the interclass correlation, one day with the most correlation was chosen as the day of an agent of that pattern. The next step is to determine the most effective model jet stream leading to rainfall, the amount of rainfall of 32 synoptic stations in the center of provinces, along with maps in heights, Omega, 1000, and 500 hp and map the convergence of moisture flux for levels of 700 and 850 hp for each of the days of the agent was investigated. The results showed that the pitch of strong jet stream in fourth pattern with a speed of 65 meters per second at the level of 300 hPa in southern of Iran along with formation of through cold Chali on the Caspian Sea, simplify the conditions for the convergence of the lower levels of Iran atmosphere, and influx of moisture from the Mediterranean Sea along with along with unstable conditions of high atmosphere, causing pervasive rain in Iran.

Forests as the lung of land part of our natural resources have an important role to play in the physical and mental health of living beings. Forest fires in Iran and especially in boreal forests had been devastating effects on the appearance of these areas. One method of prevention and risk management established within the field of forest fires is a determination of hazard distance. The purpose of this study was to determine areas vulnerable to fires in Noshahr forests. After identifying the factors contributing to the fire (slope, aspect, elevation, land cover, temperature, precipitation, distance from settlements, distance from roads), weights each of criteria and sub-criteria calculated using multi-criteria decision-making techniques and fire map were prepared in the environment ARC GIS software. The results showed that 17.32 percent of the area which is 311.8 Km² in classes risk high and very high and 17.32 percent of the area which is 311.8 Km² are located in classes risk low and very low. Furthermore, evaluate result's using of kappa statistics coefficient shows that the methods used with coefficient 0.64 are of a good accuracy zoning the forest fire risk.

If air pollution issue is not one of the acutest problems caused by mechanized civilization, undoubtedly it is one of the most complicated ones because air is spread everywhere and is being used in 24 hours. Gathering of most of the people in urban areas and high standard of living expectation with minimum price without any attention to the environment has caused to increase of air pollution density in dangerous and noticeable level. Now the growth of cities especially in developing countries causes urbanization and environmental waste. To reach a sustainable development in cities, reduction and control of air pollution can be very important. In this research 8 factors: overcrowding, precipitation, DEM (digital elevation model), distance from connecting roads, distance from green space, distance from CBD (central business district), distance from industrial centers and land use have been used as effective factors in air pollution. The information layers have been prepared in GIS (geographic information system). The evaluation and normalization of the criteria maps were done simultaneously using the fuzzy method. The analytical hierarchy process was used to weigh the factors. The air pollution zonation map was prepared in the environment of Edisi and using the Vikor method. According to The results obtained from the model, the direction of West, North- west and The Central Part of The city has the most pollution zonation. In addition, according to the results of the study for preparing the air pollution zonation map in Tabriz, the usage efficiency of the membership function in the fuzzy steps and Vikor model have been approved, and according to which, using the multi variate analysis techniques lead to increased attention and speed of the work as well as the better quality and variety in the results of the study.

The occurrence of heavy rains often leads to destructive floods, thus exploring the dominant pattern of climatic systems provides the possibility of its analysis and forecasting. Thus, the aim of this study is identifying the patterns and synoptic conditions of heavy rainfall and generated flood event in the Germi area. The recorded data of an 11 year period (2004-2014) were used in this study which is including synoptic maps of geopotential, sea level pressure, jet streams, temperature, runoff, Omega and perceptible water were investigated. The results showed that the concurrence of rainfall variable in the study area is due to a combination of local and extra-local factors. The location of the Germi area in the path of entering Caspian air masses, Anticyclone and Western cyclones, experienced heavy rainfall in every year. The results indicated that the most recorded heavy rainfall events were observed during the April, May, and June months having 36.3, 46.2, and 37.4 rainfall amount, respectively, which is responsible for the occurrence of most natural hazards, including floods in the spring season. The maximum value of rainfall was observed in June 2014 with 120.8 mm rainfall value. The main cause of heavy rainfalls in the studied temporal and spatial extent can be attributed to existing the low-pressure center over the Study area, as well as the formation of two simultaneous waves along with a blocking center over the Mediterranean Sea and two low-pressure area.

Forest fires are a major environmental problem that led to the economic and environmental damages. Forest fires are one of the environmental hazards in Iran. Naturally, it is impossible to control the forest fires. By the use of forest fire risk maps, we can identify the areas with high risk of fire and reduce the fires as well as possible. Preparing the map of forest fire risk areas as a strategy is necessary for protecting the forests against fire. In this paper, in order to prepare the forest fire risk zoning, at first the effective criteria’s and indices are identified by Delphi technique, and all of the criteria’s and the indexes were normalized by Fuzzy logic. And also the weights of criteria prepared with Analytical Network Process, then by using GIS system and integrating it with Weighted Linear Combination methods (WLC) the map of zonation of the forest fire risk in the study area was carried out. To assess the accuracy of the evaluation, the results obtained from the study were compared with the past year's fire history data of studied area. This was done using the Kappa coefficient test. The results of the comparison indicated that the prepared map has 90% accuracy for Kappa coefficient test.This result showed that the prepared map had high accuracy and efficacy.

Climate and air pollution can be a factor affecting human mortality. Ilam province has a different and contradictory climate due to geographical location, climate, and proximity to the deserts of neighboring countries such as Iraq, Saudi Arabia, Syria and the Scattering of its cities. The purpose of this study was to investigate and compare the climatic elements affecting respiratory diseases in mountainous regions and plains in Ilam province. The population under study was the number of people referred to Mustafa Khomeini Hospital in Ilam during the five-year statistical period (2009-2013) in both regions. The data on climatic elements in the years between (2009 - 2013) is presented in this study as an independent variable. In the present study, using descriptive and inferential statistics and regression models at a significant level (P

The drought is one of the important natural hazards that have direct and indirect consequences, especially in rural areas Successive droughts caused a loss of Agriculture and empty villages that sent residents have migrated to the cities. The purpose of this study is to analyze and identify the most important consequences of the 1390-1394 drought on the lives of people in the city Fereydunshahr is Choqa village Choqa population included 375 residents of the village who were heads of households using Morgan table and Krejcie 230 samples were selected. Data were collected through a questionnaire that Cronbach alpha was calculated that more than 87percent. Statistics and data using different statistical methods such as factor analysis were analyzed. The results showed that the consequences of drought in the village of Choqa in economic factors (reduction Dramdnashy and horticultural crop production, rising prices of agricultural inputs and costs associated with the production, reduction of non-agricultural income, etc.), which is a 46/25 percent of the variance. As well as environmental and social factors to the values of 89/22 and 63/15 percent of the variance, were the next category. Field studies also show that crop production and crop cultivation declined significantly. The increased production costs, the rural and social status of the village also had a lot of negative changes.

Soil erosion is one of the most important environmental problems we face today. Increasing human exploitation and lack of proper management of the natural environment has a great impact on intensifying the process of soil degradation and erosion. In this study, the erosion and sediment yield in a Kohpayeh - segzi plain with 136 thousand hectares were studied using the Revised Universal Soil Erosion Model (RUSLE). Data and tools used in the study included Weather stations data, Information 21soil sample, digital elevation model (DEM), Satellite image OLI sensors, geographic information system (GIS) and remote sensing (RS). by investigation efficient parameters in RUSLE model, including rain erosion factor, K-factor, the factor is the topography, vegetation factor, and protective operations factor, The amount of the erosion in the region has been estimated. Accordingly, on the result the annual erosion in the entire study area has been estimated zero to 95 tons of soil per hectare per year. The results showed that topographical factor with the highest coefficient of determination (R2=0.9) has the greatest impact on estimates of annual soil erosion using RUSLE model. This research approves the effectiveness of new technologies, GIS and remote sensing for estimating soil erosion.

Neo-tectonic has a very important role in the morphological evolution of each drainage basin. The tectonic history can be retrieved by morphotectonics quantitative indicators in each region. Hamedan batholith masses valleys with NW-SE direction in the South, South East, and West of Hamadan, have been influenced heavily by the geomorphological, tectonic and other eroding factors. The core of tectonic geomorphology is the study of the frequency of tectonic processes that tend to topography and surface processes. By studying Morphotectonics indexes can be assessed valleys an unstable. Evaluation of Morphotectonics indicators in the northeastern and southwestern slopes of the mountain front sinuosity Hamedan according to different heights of mountain front is purpose of this study Evaluation of tectonic activity in Alvand mass range, have been estimated by using Morphotectonics indicators in 28 sub-basin, topographic maps with scale 1:50000, satellite images, field visits and software. The results of slope length of the river (SL), asymmetric factor (Af), integral hypsometric curve (Hi), valley floor width-to-height ratio (Vf), Mountain-front sinuosity (Smf), transverse topographic (Tp) and sinusoidal of river (Sr) indicators were assessed by using IAT index. According to this index, 50% of Northeast Slope sub-basins and 37.5% of southwest slope sub-basins have gained class 3 activities which imply a more active tectonics of the southwest toward the northeast slope. Due to the erosion and geological factors, south-west slopes tectonic activity is more evident than north-east slopes. The northeast slopes Mountain-front sinuosity is 200 meters higher than south-west slopes, according to the higher density of faults on the southern slopes of Alvand can say that the lower altitude mountain-front has provided favorable conditions for reflection Morphotectonics area.

Dust event is one of the atmospheric events of the world arid and semi-arid areas that had a significant increase in recent years and negative effects in different parts. In this study used MODIS data to identify and select the best algorithm for dust detection. For this purpose, three dust events of South West of Iran detected in 2012 using five different algorithms of dust detection including Ackerman BTD, Miller, dust index, TIIDI and DUST RGB methods, and methods compared. Studies show that methods of Ackerman BTD, Dust index, and Miller need to threshold regulation for each dust event; for this reason, suitable threshold was determined for each dust event using histogram method and dust identified. In addition, TIIDI method could separate dust phenomenon from other complications on the surface of the earth but as well could not identify dust on water. In DUST RGB method as well dust identified from other complication. In addition results of images classification and accuracy assessment showed that in all three dust events, DUST RGB method has maximum total accuracy among of other methods. Therefore, based on the results of matrix error and accuracy assessment, DUST RGB method was chosen as the best algorithm for dust detection.

Today, with increasing urbanization and changing land border cities such as gardens, agricultural land, Barren land into residential areas, causing damage morphology and physical properties and hydrological basins are, This will redirect the natural flow of the water from rainfall and reduced infiltration basin is a result of problems such as flooding. Darab in Fars province and city in the study area were dry climate is Intense rains occur from time to time that the formation of rainfall runoff is significant BMP and LID are ahead in research techniques and strategies such as rain barrels, infiltration trenches, wells, Absorption, permeable flooring, bio-gardens and the use of storage tanks have been used and have shown good performance. Using information such as maps, land use, topography of the region, and rainfall statistics and modeling to model swmm5 After the reform and the implementation of the proposed method in comparison with the situation in the rain with a return period of ten years the peak runoff in the basin, 31% and maximum water level in the channel output to half the rate of 17.5% compared to current situation has increased infiltration basin In this study, we were able to construct 6 of 61 thousand cubic meters of rainwater storage tank to store it.

The water cycle and the formation of clouds in different climates are very important. Cloudiness and trends in the spatial distribution days to decide and environmental strategies are important. The aim of this study was to investigate the temporal and spatial variations days of annual changes in cloudiness is based on geostatistical methods. Methods based on data cloudy days were 43 synoptic stations from 1970 to 2010. In order to determine the spatial pattern of different methods of geostatistical interpolation was used. The measurement accuracy of the methods of validation criteria MAE, MBE and RMSE and to assess the trend of Kendall and least squares method was used. The results showed that from North to South and from West to East, Iran, the number of cloudy days is reduced and large spatial differences in the number of day's cloudiness in the country. Distribution Spatio-temporal cloudy days in the country is subject to component location and latitude factor is most effective. Results Criteria validation showed that for cloudiness Annual methods GPI and C / K and in winter interpolation method C / K, in the spring of IDW, in the summer LPI and autumn approaches RBF and EBK greater performance in the spatial distribution cloudiness of Are. The cloudy days in the country was further reduced so that more than half of the stations studied, show the significant decreasing trend. Since the introduction of cloudiness is precipitation, results in the management of risks disasters awareness and management of water resources are important.