JOURNAL OF NATURAL ENVIRONMENT HAZARDS
Year:2019 | Volume:8 | Issue:19|Papers Count:15

One of the most important and advanced forms of water erosion is gully erosion that causes the destruction of land and sediment production in many areas, resulting in a lot of economic damage. The Nemarestagh watershed is one of the sub-basins of the river Haraz which is exposed to expanding this form of erosion. It is necessary to determine the sensitivity of the area by using appropriate methods to plan its control. For this purpose, 133 gullies were first recognized and recorded through Google Earth image, aerial photography and extensive field surveys. Randomly out of this number, 99 gullies are used for modeling and 34 gullies are implemented for evaluation. The layers of effective factors including lithology, elevation, slope, aspect and vegetation and land use were prepared using ArcGIS environment. In the next step, the length and density of gullies in per class of the factors were calculated by overlaying the layers and the map of the risk zoning of gully erosion in the region was provided using the frequency ratio and information value statistical methods. The results showed that Shemshak formation with shale, sandstone, siltstone and conglomerate, elevation of 1000-1200 meters, the slope of 40-50 percents, the southern direction and poor pasture have a highest gully erosion susceptibility. The evaluation of statistical methods using the probabilistic probability showed that the information value model is more suitable for hazard zonation in the area.

Salinity is one of the most destructive processes in soils, particularly in arid and semi-arid areas. In order to use and exploitation of such soils, the soil monitoring and mapping are necessary. In this study, in order to zoning and mapping of soils, sampling was collected based on network method from Bolagh (Saveh) saline lands and the electrical conductivity of saturated soil extract was determined. Then the data had been transferred to the ArcGIS 10 software and soil mapping had been drawn. The exponential model of Semivariogram showed the best cross-validation and efficiency than the other models (spherical, linear and gussian). Also, the amount of nugget effect to the threshold was 84/43% which indicates that the medium spatial correlation for soil EC amounts in the study area. Also, the variogram effect range was calculated about 261 meters. Assessment of the resultant index indicates that the geostatistical has been able to soil salinity mapping with moderate accuracy and precision. The results showed that among five soil salinity classes, the soils of study area classifying in four Classes (including non-salinity, low salinity, medium salinity and high salinity) which highest quantities are related to middle southern regions. These results show that soil salinity in this area has high variability.

Locating and identifying vulnerable areas of the aquifer and managing water supplies use and land use is a good approach to preventing underground water pollution. Nitrate has always been considered as a water pollution index. The aim of this study was assessing the vulnerability of Meymeh aquifer to nitrate through GIS, statistical methods, and Drastic Model. Drastic Model identified the vulnerability of Meymeh Aquifer as low and medium (75-128). After calculating the drastic new index using Raster Calculation in ArcGIS, the correlation between nitrate concentrations in groundwater samples and the new drastic index was calculated. The correlation coefficient of-0/162 (before optimization) to0/842 (after optimization) has increased. These correlations were significant at the 95% probability level (P-value <0/05). To gain nitrate concentration maps, samples were taken through standard sampling principles from 10 wells and analyzed through spectrophotometry approach. Next, nitrate concentration maps were drawn using interpolation models. Combining vulnerability map and nitrate concentration map indicates that most of the area under study was safe and low-risk and only one area of Meymeh was a high-risk area with nitrate concentration above 50 milligrams per liter in underground water. According to the nitrate concentration zonation map, The highest concentrations were observed in groundwater in the southern region of the Meymeh aquifer is due to the interaction of pollution caused by farming activities, Return water irrigation, Lithology, Higher nutrition rates, Hydraulic Conductivity and The permeability of the soil.

In Iran, the vast floods are occurring frequently those are due to huge area, climate changes, land use change and temporal and spatial variations of precipitation. The current research mainly aims to assess Analytical Hierarchy Process (AHP) method to provide flood susceptibility map. In this study, different factors, e. g. elevation classes, the percentage of slope, land curvature, distance from the river, geology, land use types, curve number and soil hydrological groups are used in the Razavar watershed in Kermanshah province. The raster maps of these layers were provided by using ArcGIS10. 1 and SAGA GIS2. The flooding probability of each class for different factors as well as the importance of each factor in comparison with other factors was evaluated according to the expert opinions, and then the related weights were calculated in the expert choice software. Furthermore, the obtained weights of each class/factor were applied to every layer using Geographic Information Systems (GIS) to provide flood susceptibility map. The results showed that the percentage of the slope had the highest effects on the flood, and also distance from the river and the elevation classes are in the next priorities. The lowest factor in the flood is related to curve number. Moreover, the results indicated that about 48. 5% and 30. 9% of the study area were recognized with high sensitivity and low/very low sensitivity, respectively.

Always crises, natural and unnatural disasters have threatened the urban life and have led to cities destruction. But many cities shortly after these crises have been able to return to their ordinary life. This return can be called as resistance. Increasing in resistance of the cities against the natural disasters, especially earthquake is effective in reduction of losses and also in the recovery period of the societies. The plan makers and administers the cities, as the most important entities involved in designing the cities, have a key role in increasing the resistance of urban communities against earthquake. Physical resistance is one of the effective aspects of resistance of societies, through which the physical and geographical characteristics of the cities in disasters can be evaluated. This study is a practical, descriptive and analytic study and aims to identify the indicators and factors affecting physical resistance and to quantify and compare the physical resistance sub-criteria in old areas of Bushehr. The population of this study is the residents in old areas of Shanbadi, Aliabad, Mahkboland, and etc. 381 questionnaires consist of general and specific questions, using Liker scale, were handed out among the residents of these areas. The reliability, using Cranach’ s alpha, was evaluated for analysis of physical resistance in old areas, ANOVA and T-test have been applied to divide the areas according to physical indicators. In order to obtain the required map in these areas, GIS software was used. Finally, physical resistance indicators (e. g. access, quality of buildings, the access before the earthquake, infrastructural resistance, earthquake, resistance) using multi comparison T-test were studied. The results show that the neighborhoods in these areas are different in terms of their physical resistance indicators.

The particulate matter less than 10 μ m (PM10) and visibility are known as two important parameters in researches connected to the tropospheric aerosols and dust so that the air pollution is related to those at the specific time. This study analyzes the relationship between PM10 and visibility whit using evolutional Genetic Algorithm. The area’ s case study was Yazd city as representative of central of Iran. Visibilities data whit separation of 05, 06, 07 and 09 synoptic conditions, for 5 years (2010-2015) from Yazd Meteorology Organization; and PM10 data from air pollution control stations connected to Yazd Environment Organization have been catches. To reach mentioned mathematic relations, linear regression equation and several kinds of famous functions have been a comparison; which Gaussian function selects as the best fitness function. The results of this research, were the general equation between PM10 and visibility, PM10 and visibility whit 05 code, also PM10 and visibility connected to 09 synoptic code, using Gaussian function in 1 term; and equation between PM10 and visibility when to happen 06 and 07 synoptic conditions, using Gaussian function in 2 term that has been presentation.

One of the most important applications of satellite images is the use of it to determine and estimate the surface temperature of the earth. To investigate this, the Landsat 8 series was used to calculate and estimate the air temperature in the city of Isfahan and surrounding area. The surface of the earth's surface temperature (LST) was calculated using the Subrino window algorithm. The results showed that the use of this method on satellite images of Isfahan region, which covers a variety of urban areas, green spaces, and major industrial areas, shows the ability of this model and the proportion of these images for this purpose. The comparison of a temperature measured on the image and the temperature calculated in two of Ozone-metric and Airport stations in Isfahan shows a range of changes of about 4. 5 degrees Celsius. However, the calculated temperature in four days of the year is more than the measured temperature at a depth of 5 cm in the soil at the site of the two Ozone-metric and Isfahan Airport stations and this value is at a maximum of 4. 25 degrees Celsius above the station's temperature. The correlation relations between the LST surface temperature map and the normalized vegetation difference index (NDVI) at 9100 pixels of the area code with a correlation coefficient of 0. 445 are confirmed at a confidence level of 99% which confirmed the validity of the method used to estimate the surface temperature. .

Droughts are the expanded period during which available water is significantly lower than usual. Among the climatic phenomena that affect communities and the environment, climatic drought is one of the most complex ones. This feature makes the need for more recognition of its different aspects. The purpose of this research is to express some of the characteristics of climate drought, especially their severity in arid and semi-arid regions of Iran. After providing hourly data on average, maximum and minimum temperature as well as average rainfall, of Kerman and Shiraz synoptic stations which are representative of arid and semi-arid regions of the country respectively, and converting them into daily and monthly scales, the severity of climate droughts was calculated based on four SPI, RDI, SPEI and EDI indicators during the statistical period of 1965-2015 and at 5 different time steps. The efficiency of each indicator was evaluated in determining the characteristics of climate drought. The results showed that the drought severity estimated by each of the indices at different time steps in arid regions (Kerman) and semi-arid regions (Shiraz) has the same monthly changes and fluctuations. But in each region, based on the type of climate, the index that has the highest correlation with the others at different time steps is different. So, in Kerman, RDI6 (R2=0. 64) and RDI9 (R2=0. 70) in Shiraz had the highest correlation with other indices, and have higher efficiency for Justifying the quantitative changes of other indices. In addition, at different time steps, the SPEI in Kerman and RDI in Shiraz have good performance in determining the number of dry months. Meanwhile, in terms of the frequency of occurrence of dry months in different drought severities, the class of mild dryness (0> I>-1) with a frequency of 65% and then the moderate dryness class (1> I>-1. 5) had the highest percentage Frequency, and severe dry and severe drought (I>1. 5) had the lowest percentage of abundance (15%) at both stations.

Today, only the urban problems are not limited in the social, economic, political, cultural issues, but natural factors which constitute the substrate of cities have a significant impact on the process as well. So the ability of cities to cope with natural hazards and proper planning is of particular importance to prevent or reduce the adverse effects. The aim of this study was to assess the seismic status of physical and demographic vulnerability in Rafsanjan City against earthquake. That's why the seismic assessment of the statistical and analytical methods and assessing the physical and demographic vulnerabilities with indicators of buildings, roads, and population was conducted by using Geographic Information System Software (GIS). Also, Analytic Hierarchy Process (AHP) is used to rank the vulnerability. The results show that 52. 36% areas of Rafsanjan are in the moderate seismic hazard zone. 47. 64% area in the low seismic hazard zone. In assessing the physical and demographic vulnerabilities, 13. 51% areas of the city are largely affected, the 36/41% areas are moderately affected, and 50. 08% areas of the city have low vulnerability, However, according to the results, Rafsanjan city also has high seismic risk, but seismic analysis indicates that the probability of an earthquake with magnitude of 7 Richter scale is possible. For this reason, considering that about 50% of the city areas is vulnerable in terms of physical and functional condition so planning to reduce the risks is high important.

The country is dry and low in the water, the coincidence of this situation and its position in the global rebound belt has brought about very bad conditions. Repeaters in recent years have been affected by the severity and frequency of major events in Iran and, in terms of environmental issues, studying and managing the reduction of its effects is a priority. The purpose of this research is to evaluate the role of the transverse boundary layer in the transition, the conditions creating and exacerbating the disturbance of dust to the southwest of the country. The research methodology first extracted days with dust and a period in which this phenomenon was enormously and intensely studied in the studied area (February 21-24, 2016) for monitoring. The data boundary layer height (BLH) based on the outputs of base ECMWF, Paramtryhay Hvasphr base NCEP / NCAR and Aerosol Optical Depth (AOD) was extracted from MODIS. In addition, in order to evaluate the conditions that create and exacerbate disturbances, the numerical value of Richardson Number was calculated for two radio stations in Ahwaz and Abadan. The results showed that the boundary layer of the atmosphere in creating turbulence and transfer of dust to the country has a significant and non-interlocking role so that in every 4 days the study between the height of the borderline and the optical depth of the particles was greater than 0. 70. Unstable airborne conditions such as very deep creeping, strong rotation with a significant positive tau in the axis of the woods, along with negative omega that suggests climb, air instability, and consequently creating uneasy and turbulent conditions in the region, are very favorable and Has strengthened dust removal. The Richardson numerical value in the selected days represents the overrun of the mechanical force of the vortex generator from the thermal deterioration force, which resulted in an uneven and turbulent flow, and the mixing process was performed more easily and quickly.

The purpose of the seismic hazard analysis is to predict the extent of the strong ground movements over a certain period of time on a specific site. There are uncertainties in all the inputs of the risk analysis, each of which expresses a property. As a result, recognizing uncertainties and how they are considered by different risk analysis methods can indicate the reliability of those methods in seismic hazard assessment. Fuzzy logic is a suitable tool that is used as a decision-making method for solving problems and modeling uncertainties and ambiguities. Nowshahr Port is located in the Alborz seismic province which is one of the seismic regions in Iran. In this study, a seismic hazard estimate for a range of 200 km radius from Nowshahr port was carried out at a latitude position of 34-38 degree north latitude and 49-54 degree east longitude. For this purpose, 16 potential seismic sources have been used in the studied area. First, seismic hazard estimation was done by the Conventional deterministic method and then using fuzzy logic. According to the results obtained in the conventional deterministic method, Peak Ground Acceleration values estimated from Conventional deterministic method 0. 52g and 0. 55g application fuzzy Logic System.

Wetlands play an important role in the prosperity of society in developing countries through the provision of goods and services that are used directly or indirectly, and therefore they are valuable. In this article, the value of carbon sequestration, oxygen production, water conservation and soil conservation were estimated to assess the economic losses caused by drought. the information needed to estimate the value of the production and regulation functions were obtained from Environmental protection organizations, The Forest Service, Rangeland and Watershed and previous studies, in the year of 2015. The production and regulation functions were estimated by using the market valuation method, alternative cost and shadow price. The results show that the functions of regulating gas (carbon absorption and oxygen production) are 86920, Conserving soil and water conservation is 174004/31, 1629163/63 $. and the total value of the regulatory functions of Hamoon wetland is 165/071 billion. Estimated values for Hamoon wetland ecosystems have two major applications: first, in cost-benefit analysis, gaining economic support for the protection of Hamoon wetland and can be used to determine the number of damages and destruction of wetlands caused by drought. Second, the estimated value can be used in the production of the gross domestic product.

Sistan River is one of the main rivers in Sistan plain which has the various hydraulic structure built upon it. Parts of the river and its structures have been influenced by the entrance of sediments into the river’ s bed which are due to several reasons such as drought, extreme wind, and transportation of fine sediments. The research regions included the water entrance to Chahnime, Kohak dam, Zahak Dam, Sistan Dam, and Nohrab Bridge. In the first stage, the direction of the river in respect to dominant wind and the condition of shores facing wind are studied, and the natural and artificial obstacles, such as vegetation, natural heights, and buildings, which were in the path of the wind, were determined. In the second stage, soil texture, dry unit weight and soil coherence of shores facing wind were measured. Based on the research, the Sistan River direction was parallel, oblique, and perpendicular in respect to the dominant wind direction. The soil texture was mainly silty clay with gravel, loam, and loamy sand. However, the soil texture changed at the riversides to loam and silty loam. The liquid limit of the studied soils was lower than 25 with little soil coherence. The undrained shear strength of surface soils within the path of the river and its shores were determined less than 30 kPa. Also, the range of dry unit weight of soil in the studied area is between 1. 2gr/cmᶾ to 1. 3gr/cmᶾ and its vegetation indicated vegetation was lower than 20% near the engineering structures. The results of this study indicate that the, Kohak dam, the Sistan dam, and Nohrab bridge, have the most impact on erosion and transport of wind sediments.

In order to study the Synoptic structure of the atmospheric circulation patterns of effects on the semi-easterly snowy days of Iran an environmental-cyclic approach from synoptic climatology was used. For this purpose, the first snow days based on current weather codes were obtained (WW) from the Meteorological Organization of Sistan and Baluchestan and South Khorasan province. Based on these days, variables such as sea level pressure, temperature, geopotential height, orientation and zonal components of the wind, thickness, streamlines in various levels were taken from the website of National Center for Environmental Prediction and National Center for Atmospheric Research (NCEP / NCAR) with a resolution of 2. 5 by 2. 5 degree and the synoptic maps were prepared. The results of this study showed that snowfall in this region is a low-frequency phenomenon because of the geographical location and the type of dry and dry climate and in the formation of rainfalls in the form of solid or liquid (snow or rain) elevation has a greater effect than latitude. Meanwhile, snowfall can be affected by the influence of synoptic systems such as Siberian high and its integration with the high pressure of Europe to advection the cold air and simultaneous transmission of wet and warm air will be obtained by the low-pressure systems on the Arabian Sea, the Gulf of Bengal and the Gulf. It is necessary to state that the formation of Siberian high pressure in the lower latitudes is much more effective for snowfall. In this situation, the central pressure of this system is about 1040 hPa and line 1030 hPa affects East of Iran. In addition, the study showed that when the major part of the country (especially on the Zagros Mountains) is under the influence of local highpressure, with an anticyclonic circulation, it causes to transmission of a wet stream of Caspian Sea to the region. Other results this study are the role a strong jet stream with a speed of 65 m/s at level 300 hPa in the southeast and south Iran and the output axis of the jet stream is associated with a southwest-northeast axis. Snowfalls occur in thickness of 5300 to 5400 meter and temperature of about 3 degrees Celsius in the area.