Research Article
Fariba Esfandiyari Dorabad; Ebrahim Beheshti javid; Mohammad Hossein Fathi
Abstract
Introduction:
Landslides are amongst the most damaging geologic hazards in the world. They pose a threat to the safety of humankind lives as Well as the environment, resources and property. Compared with other natural hazards such as volcanic eruptions and floods, landslides cause considerable damage ...
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Introduction:
Landslides are amongst the most damaging geologic hazards in the world. They pose a threat to the safety of humankind lives as Well as the environment, resources and property. Compared with other natural hazards such as volcanic eruptions and floods, landslides cause considerable damage to human beings and massive economic losses (Guzzetti, 2005). According to preliminary estimates, about 500 billion riyals annual are caused economic damage in Iran by landslide occurrence (Hosseinzadeh et al., 1388:27). Much literature available on landslide hazard assessment methodologies broadly falls into three main Approach groups: qualitative, quantitative and artificial intelligence (AI) approaches. in general, a qualitative approach is based on the subjective judgment of an Expert or a group of experts whereas the quantitative approach is based on mathematically rigorous objective Methodologies. Artificial Intelligence (AI) techniques can make use of heuristic knowledge or pattern matching technique as opposed to solving a set of mathematical equations. The AI broadly covers Artificial Neural Networks (ANN), Expert system, and other heuristic knowledge-based or rules-based techniques. (Neaupane and Piantanakulchai 2006:281). For the Landslide Susceptibility Mapping can be used a variety of models, such as logistic regression, Analytical Hierarchy Process (AHP), Analytic Network process (ANP), artificial neural network, the bivariate statistical models, LNRF, fuzzy logic models and etc. Usually choose the most appropriate approach and model is done based on the data type, the scale of the study area, the scale of analysis and Knowledge of researcher.
Study area:
In this study siyahrood catchment has Zonation for landslide susceptibility by using weights of evidence models (Bayes' theorem). The basin is located in the province of Gilan. The catchment area is 437 km and is sub-basins of the Sefidrood River.
Materials and methods:
The weight of evidence (WofE) method (Bonham-Carteretal.,1989) has been used to evaluate shallow-landslide susceptibility and has been tested as a useful spatial data model for various applications including mass-movement studies, mineral research, and groundwater spring mapping (Mark and Ellen, 995; Poli and Sterlacchini,2007; Barbieri and Cambuli, 2009). .It takes into account the relationships existing amongst the occurrence of a supporting evidence (shallow landslides in this study) and the distribution of causal factors (shallow-landslide predisposing factors in this study) The WofE is a statistical method based on the Bayes' theorem (Denison et al., 2002). This methods first applied to mineral exploration in1988 (Bonham-Carter et al., 1988) and Subsequently, Van Western (2002) applied the method for Landslide susceptibility assessment. Bayes’ theorem can be written as:
Equation (1) P(s│B_i )= (P(B_i│s)×P(s))/(P(B_i))
Where P (Bi | s) is the conditional probability to have Bi given s, P (s) is the prior probability to find s within the study area (AS) and P (Bi) is the prior probability to find the class Bi within the study area AS. In this study landslide susceptibility zonation has been done using several natural and anthropogenic parameters Such as (lithology, distance from fault, distance from river, rainfall, land slope, aspect, land use, vegetation density (NDVI) and sediment transport index (STI) stream power index (SPI) and topographic wetness index (TWI )).
Results and discussion:
After the Weights classes were obtained using the model for each parameter, Weights was applied to each class in the Arc map software and eventually with overlay parameters was obtained landslide susceptibility maps. The final Maps was classified In 5 susceptibility class using the method of natural breaks (very low susceptibility, low susceptibility, moderate susceptibility, high susceptibility and high susceptibility). According to the results of the model and the map developed in the lithology layer, Most of the weight is allocated to Class B (old alluvial terraces and High alluvial fans). Moderate range among the different classes of land use and north and northwest directions in the aspect parameter Have the greatest impact on landslide occurrence. As well as slope of 20-10 degrees and 10-5 degrees, respectively and in the layer distance from the river, 100 meters from the river have the greatest impact in landslide occurrence.
Conclusion:
Assessment models with using landslides occurred in the area show that with increasing risk class, landslide density in the class increases And 59 % of landslide, has occurred in very high susceptibility class. While the area of this class compared to total area of the region is only 10.5 percent. Although Classes with very low susceptibility, low and moderate susceptibility are included approximately 71 percent Area of a Region, But only a small portion of the landslides occurred (16.7%) in these classes While the roughly 83. 3 percent of landslides occurred in the area are located in the fourth and fifth class (high and very high susceptibility). Due to this can be said that the model has a good functionality in the area terms of the prediction of landslides.
Research Article
Seyed Mohammad Tajbakhsh; Hadi Memarian; Majid Asiaye
Abstract
1. Introduction
Generally, landslide studies include process identification, risk analysis and landslide risk prediction (Taleby and Ezaddoost, 2012). Nowadays, there are different methods for landslide simulation such as statistical, descriptive and process-based approaches. However, most studies in ...
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1. Introduction
Generally, landslide studies include process identification, risk analysis and landslide risk prediction (Taleby and Ezaddoost, 2012). Nowadays, there are different methods for landslide simulation such as statistical, descriptive and process-based approaches. However, most studies in Iran are based on statistical and descriptive methods (Taleby and Ezaddoost, 2012). Landslide zonation models are mostly based on grid analysis and landslide density per unit area. Meanwhile, they need more data layers to obtain more accurate results. However, deterministic models like SINMAP has been established based on numerical computations and embed precise physical parameters. The SINMAP model has been applied with different applications around the world (Acharia, 2003; Waver & Nowocien, 2003; Deb & El-Kadi, 2009; Terhorst & Kreja, 2009; Memarian et al., 2013). This study is mainly aimed at landslide risk zonation using SINMAP, while specifically analyzes the physical, tectonical and morphological parameters which affect the stability of slopes.
2. Study Area
The Havenan village has been located in the southwest of Birjand, the north of Bagheran Mountain with a coordinate of 59° 10’ 12” E and 32° 48’ 11” N. The Havenan landslide zone is not uniform. Its failure length and width is 1500 m and 500 m, respectively. The height difference between the crest and toe of the failure is 350 m. The main cliff is 20 meters high and the movement extent is higher than 10 m. Therefore, slope movement speed is low and already is in suspension condition (Saman SadRood Consulting Engineers Co., 2010).
3. Materials and Methods
Landslide risk zonation was performed on the land unit 1-8-1, which mainly involves Phyllites, Schist, and Split formations with rocky outcrops and steep slopes.
SINMAP methodology is based upon the infinite-slope stability model that balances (with edge effects neglected) destabilizing components of gravity against stabilizing components of friction and cohesion on a failure plane parallel to the ground surface. Based on the infinite-slope form of the Mohr–Coulomb failure law as expressed by the ratio of stabilizing forces (shear strength) to destabilizing forces (shear stress) on a failure plane parallel to the surface, the safety factor (SF) calculation in SINMAP is:
where Cr is root cohesion (N m−2), Cs is soil cohesion (N m−2), θ is slope angle (°), ρs is wet soil density (kg m−3), ρw is the density of water (kg m−3), g is gravitational acceleration (9.81 m s−2), D is the vertical soil depth (m), Dw is the vertical height of the water table within the soil layer (m), and Ø is the internal friction angle of the soil (°). θ is the arc tangent of the slope S, expressed as a decimal drop per unit horizontal distance.
A variety of resources were used to determine the values of model calibration parameters (Saman SadRood Consulting Engineers Co., 2010; Memarian & Safdari, 2009; Ab Pooy Consulting Engineers Co., 2008; Morgan et al., 1998; Nakhjavani, 1977). The estimated values of the parameters Cr, Cs, h, and ρs were equal to 200 (N.m-2), 2000 (N.m-2), 0/45 (m), and 2000 (Kg.m-3). The quantity (T/R)sinθ [m] may be thought of as the length of hillslope (planar, not convergent) required to develop saturation in the critical wet period being considered. This concept may be useful for establishing field estimates of R/T through the field identification of the limits of surface saturation (Memarian & Safdari, 2009). Therefore, in this work, this parameter was determined using field investigations and the Havenan’s landslide profile (Saman SadRood Consulting Engineers Co., 2010).
4. Results and Discussion
In order to a precise analysis of the Havenan landslide zone, it was systematically overlaid with 100 points and they introduced as the landslide point to the SINMAP. According to results, 71% of the landslide zone was grouped into the “quasi stable” and “stable” classes. The 24% of the studied zone was classified as the “lower threshold” slope zone and only 3% is grouped into the “upper threshold” zone. Therefore, less than 30% of the Havenan landslide zone showed a medium to high sensitivity to landslide risk. Results showed that only a small area of the landslide zone was placed within the “saturated” region. Thus, other external factors may affect the stability of the Havenan landslide zone.
The Havenan region has been impacted by the three series of main faults, i.e. Havenan, Yusht and Mazar. The intersection of these shear zones has created romboedric blocks. Rock series has been cracked and transformed by these intersected joints. Therefore, the volume and instability of the hillslope has been increased. Consequently, the landslide event is expectable. Dynamic loads and wash off of the heel’s materials play an important role in slip continuing. Furthermore, the transformation of Peridotite to Serepentinite, Brucite and Talc increased the volume and instability of the hillslope. The hillslope instability has been amplified by the Bagheran Mountain tectonic upraise and dynamic stresses (Gholami & Khatib, 2000).
5. Conclusion
The SINMAP simulation results with field investigations established that less than 30% of the Havenan landslide zone has a sensitivity of medium to high to landslide risk. A small part of the landslide area was classified in the “saturated” zone, as well. Hence, in addition to topography, hydrology and soil conditions, other external factors must be effective in landslide occurring. These factors are mainly including the placement of the Split on the Serepentinite and the existence of two series of parallel fractures with the faults Havenan and Mazar. The hillslope instability has been increased by the Bagheran Mountain tectonic upraise and cyclical seismic events.
Research Article
Maryam Fattahi Bandpey; Mohammad Ghafoori; Gholamreza Lashkaripour; Nasser Hafezi-Moghaddas
Abstract
Introduction
Landslides are among the most hazardous natural disasters. In the North parts of Iran (Alborz Mountain belt), landslides occur frequently due to geologic and climatologic conditions with high tectonic activities. In recent years, growing population and expansion of settlements and life-line ...
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Introduction
Landslides are among the most hazardous natural disasters. In the North parts of Iran (Alborz Mountain belt), landslides occur frequently due to geologic and climatologic conditions with high tectonic activities. In recent years, growing population and expansion of settlements and life-line projects over hazardous area increased the impact of natural disasters in Mazandaran Province. These events caused widespread damage to roads, farmland and other infrastructures in the area. That results, annually,millions of dollars financial defects excluding casualties and unrecoverable resources.
Landslide Hazard Zonation (LHZ) maps were produced to evaluate the potential of slope instability in the region. The aspect factor is one of the useful and applicable layers in many landslide hazard zonation methods. According to previous studies and existing definintions, The highest number of landslides event occurs in the north (and west) aspect and The lowest number of landslides in the south (and east) aspect. This phenomenon is said to be due to the low sunshine and also the accumulation and existence of water and moisture in north and west aspect in the northern hemisphere. Nevertheless, it is observed that this condition is not true in many regions and the aspect itself is influenced by other factors in this study.
In addition to examining whether this layer has a positive role in involved landslide events or not, we calculated landslide density in each class of aspect and then we investigated the most determining factors in the performance of the aspect factor on landslide events in Babolrood Watershed.
Study area
Alborz Mountainous in the north of Iran constitutes a narrow belt with 100 km wide only. These mountains are a Part of Alpine-Himalayan system in western part of Asia which wraps around the South Caspian Sea from the northwest to northeast of Iran (more than 1500 km). The study area (Babolrood watershed )is located in Mazandaran province in Central Alborz. It covers an area of about 1492/97 km2 and is located between Latitudes 36 N to 36°33 '00" N and Longitudes 52° 25' 00" E to 52° 55' 00"E. The elevation of the study area decreases from south to north along the Babolrood River.
The geological setting of the area consists of a series of sedimentary rocks mainly limestone, dolomite, marlstone, siltstone and sandstone. These rock units belong to marine geological formations of Jurassic to late Tertiary age. Quaternary deposits of alluvial have a widespread distribution over the land surface especially to the northern part of the area adjacent to the Caspian Sea. The area is part of Alborz Mountain and is known for its active and strong tectonic activity with several destructive earthquakes in the past. The highly folded and faulted rocks are associated with active tectonics in the region. The morphology of the area is directly related to the rock types and geological features of the predominant formation.
Materials and Methods
Data preparation is the first fundamental and essential step for this study. In this study GIS database was mainly composed of two parts: landslide location map and landslide predisposing factor maps. Although the region faces high potential of landslide occurrence, because of the imposing geomorphological characteristics and high density of forest cover, the available information is very limited. Therefore Landslide locations of the area (1:20,000 scale), were detected by image interpretation (aerial Photos 1:20,000) and verified by fieldwork .an essential spatial database of landslides was established using GIS techniques. digital geology map and fault map of the area were prepared based on combination of two analog geological sheet maps at 1:100,000 scale, namely Ghaem Shahr and Amol, (Geology Survey of Iran). Constructions of Aspect thematic map was from Digital Elevation Model of the area with 10 m resolution.
Results and Discussion
To find positive role of aspect factor on landslide occurrence in babolrood watershed, Landslide density was calculated in each class of aspect layear. The result shows , Aspect can not has positive role on landslide occurrence in this area. In the next step, we investigated the factors that might change its positive impact. According to studies was conducted, lithology and faults in the study area have the highest impact on landslide occurrence. We therefore evaluated the impact of aspect with regard to these factors on the landslie occurrence in study area.
In Central Alborz, geology is a major controlling factor for landsliding. We observed that the performance of aspect is difrent on Various lithologies. it can be seen that the lowest Aspect impact belong to areas with some geological layers outcrops, such as, K2 , PEm,l,s , M2,3 m,s,l , Q , OM1m,c,s These groups are mainly including, Shale, Marl, Marly limestone and old landslide, which mostly are soluble , fissile and easily weathered materials. The highest Aspect impact belong to some geological groups such as Jl , PlQ cms , TR3Js ,TRe2.
it shows very low correlation with landslide occurrences and Aspect factor where lithology is mainly including Marl, Marly limestone, Shale and where is the nearest distance to the fault for all formations. Also result shows very highe correlation with landslide occurrences and Aspect factor where lithology is mainly including resistance and strong stones like sandstone, dolomite, cherty dolomite and limestone and also in farthest distance from fault for all formations.
Conclusion
Landslides are natural phenomena which often have detrimental consequences. Landslide hazards can be systematically assessed by using different factors and methods. The aspect factor is one of the useful and applicable layers in many landslide hazard zonation methods. in some regions the aspect itself is influenced by another factors . In this study the relationship between landslide locations and Aspect factor was investigated and it was found that the relationship between the Aspect and the occurrence of landslides is low. Also the importance factors that cause negative impact of aspect on landslide occurrence in study area was identified. We therefore evaluated the impact of aspect with regard to these factors (lithology and fault) on the landslide occurrence in Babolrood Watershed in the north of Iran. We observed that the performance of aspect is difrent on Various lithologies. The results of calculation landslide density in each aspect class and for each formation seperatly shows that the aspect factor in some formation mainly including Shale, Marl, Marly limestone has negative impact and in formation inclouding strength rocks like sandstone, dolomite, limestone shows positive impact on landslides occurrence.
Also aspect impact in nearest distance from fault and Furthest distance from fault was studied. And results shows that in nearest distance from fault , aspect factor has negative impact and in Furthest distance from fault , it has positive impact on landslides occurrence . Finally, it was found the Aspect effect is minimized in the formation which mostly are soluble and easily weathered and where is nearest distance from fault,
Research Article
Hossein Malakooti; Samira Babahoseini
Abstract
Introduction
Atmospheric processes and their interactions with ground surface responsible for formation and evolution of a heavy dust storm are important for identifying dust transport pathways. Spatial and temporal distribution of Middle Eastern dust for a severe dust event during 4-8 July 2009 was ...
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Introduction
Atmospheric processes and their interactions with ground surface responsible for formation and evolution of a heavy dust storm are important for identifying dust transport pathways. Spatial and temporal distribution of Middle Eastern dust for a severe dust event during 4-8 July 2009 was analyzed by Weather Research and Forecasting with Chemistry (WRF/Chem) model simulations, in-situ and remote sensing observations. Analyses of simulated Weather conditions, during maximum dust concentrations in low level, were occurred with high pressure gradient and high advection in present of cyclonic system. This condition was caused strong surface wind shear over known dust emission sources over Iraq. This frontal cyclone was forced soil to eroded and dust to dispersed and transported for a significant long distance. The fine dust particles (< 1µm) with significant concentration were crossed Zagros mountain range and affected Tehran mega-city on 6 July 2009 and after two days left Iran from North East. The simulation results were found to well reproduce spatial and temporal distribution of mineral dust concentrations according to visible images based on the high-spatial resolution NASA MODIS, and reported hourly visibility in synoptical stations network. The performance of WRF/Chem was acceptable for simulation of spatial and temporal distributions of dust storm along affected area during simulated period.
Study area
In this study, one heavy dust storm that was formed over Iraq and then was crossed Iran to Turkmenistan and Afghanistan north in early July 2009 is analyzed.
Materials and methods
For this study, the WRF/Chem regional model was applied to simulate the formation and evolution of a heavy dust storm during the days 26 June to 8 July 2009. The NCEP Final Analysis data were used as meteorological initial and boundary conditions. The simulation was configured with 3 nested domains (with 81, 27 and 9 km horizontal resolution and with 41 vertical levels to 50 hPa) that the inner domain covers the area under influence of selected dust storm. The initial and boundary dust concentrations was considered to be zero during the simulation. The dust physics of GOCART model, such as dust emissions, transport, dry deposition, and gravitational settling in WRF/Chem was applied for dust storm simulation. In this study, the mineral dust aerosols was partitioned into 5 size bins with mean radius of 0.6, 1.2, 2.4, 4.5, and 8.0 μm, respectively. The dust emission flux in each bin p (Fp) is size-resolved, which is calculated by taking into account the soil particle fraction, erosion factor, surface wind velocity, and the threshold velocity of wind erosion.
Result and discussion
The summer Shamal winds regime is prevailing phenomenon in Middle East central region (from late May to early July∼40 days) that lifting dust from Iraq, Iran and adjacent regions are usually associated with low pressure anchored over southern Iran that forms a strong baroclincal gradient with a semi-permanent anticyclone over northern Saudi Arabia. The convergence zone between the two pressure systems induces high-velocity, turbulent winds for regional dust transport during a time of intense convection over the Tigris–Euphrates floodplain due to very high surface temperatures. From mean see level pressure patterns, on July 6th, summer Shamal formation mechanism is established over Tigris and Euphrates basin and a frontal cyclone over Mediterranean region formed with significant upper level forcing. After that along the intensification of this frontal cyclone and its entrance over Iraq, the dust formation and its ascending is accelerated over this source. The final erosion by this system was formed a heavy pre-frontal dust, that along its track, heavy dust was crossed Zagros mountain range and was formed a long-rang dust transportation.
In the beginning storm (on 4th July), Iraq was suffered by high dust concentration background especially over the north due to frontal cyclone forcing and strong dust emission in this area. After approaching of cold front and surface wind shear to the Iraq south, it is occurred a huge dust emission over Tigris and Euphrates basin. On 5th July, due to passage and forcing of frontal cyclone over Zagros mountain range, great dust emitted and ascended has allowed to cross the mountains. On 6th July, due to presence of frontal cyclone over central of Iran, mass of dust suffered deeply this area such as Tehran and on other side; Iraq was experienced lower dust concentration in this time. The presented dust distributions in last section are fully observed in spatial distribution of simulated dust concentration. The Shamal wind pressure pattern is still active on 2th July and it was caused significant emission and on 4th July, Shamal wind pressure pattern is destroyed by frontal cyclone forcing and it is coasted huge dust emission over Iraq North and on 6th July, the frontal cyclone was positioned over central of Iran with significant dust transportation and on 8th July, the Shamal wind pressure pattern was again activated and dust plum was left Tehran nearly.
The most dust emission flux and near surface concentrations have occurred over third bin with effective radius equal to 2.4 µm and on other side, first bin with effective radius equal to 0.5 µm have played most mobility and with significant concentration over long distance from its sources and showed biggest fraction of concentration over Tehran. Also sand distribution in fifth bin with effective radius equal to 8.0 µm showed significant concentration only over sources regions especially during dust storm formation on 2th July.
Conclusion
It can be concluded from this study that in late of summer with presence of Shamal wind regime over Iraq and after forcing of a dry deep frontal cyclone is able to produce a long rang dust storm alone the Middle East. In this study, it is become clear that WRF/Chem with GOCART dust physical parameterization is nearly sufficient technique for dust storm simulation. It means that this configuration is able to simulate correctly spatial and temporal dust distributions during intense dusty conditions. It is clarified that dust source in Iraq such as Tigris–Euphrates floodplain have high potential for huge emission during summer Shamal and intense frontal cyclone activity during hot and dry conditions. By frontal cyclone forcing, clay and silt particles, smaller than 2 µm are able to transport several thousand kilometers from their sources from Middle East central region, especially during summer. It suggests testing other physical parameterizations in order to study of sensitivity of simulations of dust storm to them and also suggests testing of meteorological and chemical data assimilation techniques by forcing in-situ and satellite observations to the simulations.
Research Article
Mohammadreza Mohammadpour Penchah; Mohammad Hosein Memarian; Seyed Majid Mirrokni
Abstract
Introduction
One of the factors that affect the climate of arid and semi-arid areas is dust storm. Numerical models are new methods for evaluation of dust storms which can also be used for forecasting dust storms. Weather patterns that lead to dust outbreaks can be simulated using computer models that ...
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Introduction
One of the factors that affect the climate of arid and semi-arid areas is dust storm. Numerical models are new methods for evaluation of dust storms which can also be used for forecasting dust storms. Weather patterns that lead to dust outbreaks can be simulated using computer models that support a wide range of simulations related to the long-range transport, dispersion, and deposition of aerosols. Mesoscale atmospheric models are widely used to capture the complex flow and meteorological parameters essential in dust outbreaks (for example, Ginoux et al, 2001; Zender et al, 2003; Kim, 2008).But one of the main problems in the study of contaminates such as dust is to quantify the relationship between air quality and pollution sources. Identify the source of infection is the first step in the process of determining an effective strategy for controlling pollution. One way to find the sources of pollution is back trajectory this means that the back trajectories from the receiver site can be used to specify the source location (Petzold et. al. 2009). Today, a coupling of meteorological and trajectory models are common methods in studies of dust storms.
Yazd province is one of the low rainfall areas in the center of Iran that is almost covered with desert and sandy plains. Consequently, this province is frequently faced with dust storm phenomena. In this study, owing to lack of numerical studies of dust storm in Iran, dust storms of Yazd province were analyzed using numerical models. We used two numerical models, Weather Research and Forecasting (WRF) model and HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. WRF model analyses were used to investigate meteorological conditions in the center of Iran and HYSPLIT back-trajectory analyses were used to investigate the wind patterns that led to dust outbreaks by evaluating air transport pathways reaching Yazd area during dusty days.
Study area:
Yazd Province is one of the 31 provinces of Iran. It is in the center of the country. The province of Yazd has one of the driest climates in Iran due to its location east of the Zagros Mountains. Yazd is the driest major province in Iran, with an average annual rainfall of only 60 millimeters (2.4 in), and also the hottest north of the Persian Gulf coast, with summer temperatures very frequently above 40 °C (104 °F) in blazing sunshine with no humidity. Due to this climate and geographical position, the province of Yazd have been subjected to dust storm phenomena and have been suffering from large damages.
Materials and methods
In this study numerical models are used to investigate and forecast of dust storms. At first, Dust storms in the period of 2000-2009 were studied and dust storms which reduced visibility to less than 1000 meters were extracted. Then one of the strongest dust storms on 29 May 2003 was analyzed in detail. The Advanced Research version of WRF (ARW) was used to produce atmospheric fields at a high resolution over the study region. HYSPLIT model was used to compute simple air parcel trajectories as well as dispersion and deposition simulations. 2 nested domains of 45 and 15 km horizontal resolutions and 28 vertical levels was defined in WRF model that first domain was used for synoptic analysis and second domain was used for analysis of convergence zones and convective motions in the center of Iran. The model was integrated continuously for 48 h starting from 00UTC of 28 May 2009. Initial and boundary conditions were adopted from National Centers for Environmental Prediction Final Analyses (NCEP FNL) data available at 1° horizontal resolution. Boundary conditions were updated at 6-h intervals during the period of model integration. Then WRF outputs converted to format of input data for HYSPLIT model and this model was run to investigate the source of dust storm using calculation of back trajectories from receptor site. The back trajectories provide the Lagrangian path of the air parcels in the chosen time scale, which will be useful to identify the source locations of the pollutant that fall in the track of the back trajectories. Also for reduce uncertainty of back trajectories, trajectories were calculated at different altitudes (10 m, 500 m and 1000 m).
Results and discussion
Results of this study indicated that 20 dusty dates with visibility less than 1000 meter were occurred in Yazd station. Most of these cases occurred in February to July and in most of these cases wind direction were west and northwest. Synoptic and dynamic analysis of dust storm on 29 May 2003 using WRF outputs shows that passing of cyclonic systems of high levels and surface heating create strong instability and high surface wind speed in the region that this higher surface wind speeds lead up dust and sand. These conditions are associated with deep mixed layers and convective conditions before storm and a maximum area of strong convergence of surface wind at the time of starting dust storm and dust storm has formed. Back trajectory analysis using HYSPLIT model indicated that Gavkhoni marsh in southern part of Isfahan province and arid lands around it are the sources of the considered dust storm.
Conclusion
In this study it was shown that the use of numerical models and appropriate approach to assess and predict dust storms. The models were used in this study were Weather Research and Forecasting (WRF) model and HYSPLIT trajectory model. For the case that investigate in this study WRF model simulated the wind flow under the influence of an existing cyclonic system during the study period. The passage of the cyclone with cold air in the central regions of Iran simultaneously with the heating surface area has created severe instability and formed the dust storm. Further, the back trajectories obtained from HYSPLIT model predict winds come in the quadrant between north and west where the Gavkhoni dry salt marsh is located.
Research Article
Issa Ebrahimzadeh; Diman Kashefi
Abstract
1. Introduction
The earthquake is a disaster which always threatens our country due to specific geographical conditions.
According to official statistics, in the past 25 years, 6% of country’s casualties had been due to the earthquake. On average every ten years an earthquake of magnitude 7 on the ...
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1. Introduction
The earthquake is a disaster which always threatens our country due to specific geographical conditions.
According to official statistics, in the past 25 years, 6% of country’s casualties had been due to the earthquake. On average every ten years an earthquake of magnitude 7 on the Richter scale occurs in the country (Givechi and coworkers 2013:102). Temporary accommodation is as an essential step in the management of the crisis after the event (Zargar, 1990). The aim of this study is to locate suitable places to build temporary accommodation camps in the aftermath of natural disasters in Piranshahr.
Due to this fact, this article seeks to find answers of these questions, because it is not predicted space in this existing condition, in the environmental disasters can the city meet and accommodate victims? And in consideration of open spaces as places of temporary accommodation, is transmittance of these spaces in the city optimized and balanced, and can it answer and accommodate the injured accommodation?
2. Study Area
Piranshahr is located in the southwest of the west Azarbayjan’s province and in the border of Iraq and Iran. This city with an area of about 4844 acres is widespread in a vast plain that is 1430 to 1460 meters above sea level. Piranshahr is limited to Oshnavie and Naqadeh from north, and to Sardasht from south, and also from east it is limited to Mahabad. According to the census of 2011, population of Piranshahr had been 72,722.
3. Material and Methods
The method of this study is descriptive-analytic. Available data is analyzed by using these software, IDRISI, Super Decisions, ARCGIS, AUTO CAD, and FUZZY, ANP models. Finally, after determining affective measures to find temporary housing locations and providing different maps and layers, the final plan for the construction of temporary accommodation provision has been suggested.
4. Results and Discussion
After analyzing affective factors and determining required locative and descriptive information, criteria to locate suitable sites of temporary accommodation were provided, which includes ten layers of population density, proximity applications, vulnerabilities, access to roads, health centers, education centers, security centers, green areas, arid lands and fire stations. At the end to perform the operations of finding location and leading to suitable areas to locate temporary accommodation, the standard maps of previous stages were transferred to GIS software and final maps of the previous stages are combined using AND logic, then the final map prepared for locating.
5. Conclusion
The result showed that the areas of the city with compatible applications and also with enough and open spaces to establishment of victims are suitable, therefore, the east part of the city due to its old context, high vulnerability and population density for this project, is in priority.
And the northern part of the city due to the population density and the presence of open spaces and convenient access has high capability to accommodate victims there. 11 suggested places are considered for this project which among them green areas, arid lands and schools have the most points for temporary accommodation, therefore, 4 parks in the city with a total area of 2.6 hectares, and 7 schools to create 3 camps with 6.4 acres and ultimately 3.6 hectares of arid lands are considered as a priority areas in this plan.
Research Article
Tahereh Sadeghloo; Hamdallah Sojasi Qeidari
Abstract
Introduction
Flood is one of the most common natural hazards that are considered as a phenomenon, causing loss of lives and public property and bringing untold misery to the people, especially those in the rural areas. There is also a larger economic impact, as they derail economic activities, thus ...
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Introduction
Flood is one of the most common natural hazards that are considered as a phenomenon, causing loss of lives and public property and bringing untold misery to the people, especially those in the rural areas. There is also a larger economic impact, as they derail economic activities, thus affecting growth. Over the years, several expert committees have studied the problems caused by floods and suggested measures for their management to the Government. Different measures have been adopted to reduce the flood losses and protect the flood plains. Depending upon the nature of works, flood protection and flood management measures may be broadly classified as under: (a) Engineering / Structural Measures, (b) Non-Structural Measures, (c) Integrated flood management (IFM); as a new approaches for flood management, integrates land and water resource development in a river basin, with a view to maximizing the efficient use of flood plains and minimizing loss of life. A participatory approach which includes a representative range of stakeholders in the decision making process is another key component of IFM. Community activities play an important role as a front line at each stage of flood management that is preparedness for response to and recovery from flood disaster. In addition of people participation, the governmental support systems, with capable cadre is so effective in a successful IFM process. Therefore, in this paper the main goal is strategic flood management in rural area as a vulnerable place in front of disasters and hazard, with emphasize on government and local community participation.
Study area
Iran’s north and north east area are counted as flood prone areas. Especially, in Golestan province, having the plenty river and the productive lands near the rivers that are attractive place for population, cause to increase the risk of flood happening. Due to the geographical and climatic conditions, this state has a lush and ripe river that emanate from Alborz Mountain as; Atrak River, Gorganrood River and Ghare Suo River. Mean while, Ghar- Chai Basin of Ramyan County, is one of the sub- branches of Gorganrood, which flow in the east of Golestan province.
Materials and methods
For achieving to paper goal, has used of descriptive- annalistic methodology and SWOC (SWOT) and MCDM technique. A SWOT analysis looks at future possibilities through a systematic approach of introspection into both positive and negative concerns. In this research number of Strengths (S) are 5, Weaknesses (W) 11, Opportunities (O) 6 and Constraints(C) 6 case. Data collection does in 15 rural points in study area. After of recognizing central strategies, used from TOPSIS model for ranking of strategies related subject.
Result and discussion
After the data gathering and extracting the joint internal and external effective factor in rural flood management from local community and experts, the private strategic matrix based on strengths, weakness, opportunities and treats as effective indexes in final participatory management strategy for flood management was proposed. In the second step, these indicators were scored again by locals and experts and After calculation, the best strategy in the area of strategic focus for achieving participatory management flood was determined based on the average of locals and experts scores. The obtained result show that the scores average of external factor is more than internal factor from both local people and experts. Also, conservative and revising strategies are selected as a focal strategy for action in the context of achieving cooperative management of floods in rural areas.
Conclusion
Risk management process traditionally has taken place by many approaches and tools aimed at reducing injuries and fatalities caused by environmental hazards on human communities. But in the last few centuries due to the dominance of technology-based development paradigm in planning and management, focusing on structural approach to crisis management was more than the past. But the poor results of structural approaches application, guide planners into a combination of both approaches for crisis management. Based on new paradigm in disaster management, the local community has important role as a supplement for this combinative approach and for achieving to the purposes of disaster management cycle in precaution, preparedness and mitigation of the impacts. Rural communities Participation as key stakeholders in the field of risk management can be implemented alongside of experts and officials activities, and cause to cost reduction and success of projects and crisis management in rural areas.
Research Article
Mohammad Aryamanesh
Abstract
Abstract
The study of natural disasters is one of the most important primary principles for the growth of developing cities and the development of infrastructures. To this end, evaluating geodynamic activities using morphological data is considered one of the most pivotal applied methods. In this study, ...
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Abstract
The study of natural disasters is one of the most important primary principles for the growth of developing cities and the development of infrastructures. To this end, evaluating geodynamic activities using morphological data is considered one of the most pivotal applied methods. In this study, it was tried to detect active faults in Yazd province using desert studies and remote sensing data. The results showed that there are at least five active faults along the eastern to north-eastern part of this ancient city. These faults are considered as serious hazards for this area. A comparison of the position of these faults with seismic activities is indicative of the seismic correspondence in this area. It goes without saying that the passage of any kind of main arteries and structures including road ways of gas, electricity and water lines or other urban infrastructures require specific arrangements.
Introduction
Active faults are those types of faults which are the result of rock plastic deformation. This type of deformation occurs without breakage of the rock and affects the whole faulted rock unevenly. This phenomena is closely related to the earth’ internal order to achieve stable equilibrium. In most cases, faults are the source of surface fracture. One of the pivotal tools for detecting these dynamic phenomena is to use earth morphological young deformations. Yazd city is deemed to be one the inactive areas of Iran by most people. In this study, it is tried to investigate Yazd city in terms of active faults.
Yazd city is a located in Central desert, 667 km far from Tehran. According to UTM coordinates. The geographic coordinates of the Yazd Province is limited by the eastern longitude 54◦19'56'' to 54◦23'36'' from Grinvich meridian and 31◦55'21'' to 31◦52'18'' of northen latitude from Equator. This area is between eastern 815187 to 821009 of eastern and northern 3530575 to 3536800. Yazd city is the capital city of Yazd Province.
The study tectonic area
The location of Iran plate among the Arabian plate in the east-south, Indian plate in the south-east, Afghan plate in the East and Turan plate in the noth-east has led to the creatiomn of a convergent area. Convergent, compressive forces has led to faulting and inverse folding in Iran’s crust. In the study area along Bahabad, Anar, Chapduni and Dehshir the old faults are activated. The movement of Quaternary alluvium proves this fact. The frequency of the Quaternary activities is indicative of the continuation of these movements in the area. The evidence which exists in the Iran’s Central Plateu is a manifestation of the removement of the thrust faults. To this end, satellite images and common geodectic methods are used to study this phenomenon and its behavior in the suburban areas. The results of the study showed that in north eastern part of Yazd four active areas whose activities have been formed in the Quaternary era. This gainsays the tectonic inactivity of Yazd city.
The study of Fault positions
Faults are wavelike structures which are the results of the deformation of the layers and other plate surfaces in rocks. Faults existing in the nature vary from microscopic to macroscopic scales of several kilometers length. From morphological point of view, faults have different shapes, including anticline, dome and deformation of layers, plunging faults and asymmetric faults. In order to study faults, we must first determine the type of the target fault.
Surface faults
Hidden faults
Active faults
The investigation of the faults of the study area was carried out by using ETM++ Landsat satellite images, geological maps and desert tours. Regarding the magnifying capability of the Google Earth pictures, they were also used for final control and investigation of large scale facies. Faulting is the most obvious manifestation of earth crust deformation. This phenomenon is strongly dependent on the internal earth order in order to reach stable equilibrium. Moreover, they are closely related to folding and surface fractures and in most cases, faults are the source of surface fractures. These changes are quite manifest in alluvial trace and uplifting of the earth in every area. The foldings in an area may sometimes create faults. Then, due to their gradual and continuous activities, some of these faults remain hidden under the surface.
Conclusion
Detecting morphological phenomena plays a very important role in evaluating the seismicity of an area. Recent studies showed that the eastern part of Yazd city is surrounded by many active faults. These faults have moved the quaternary sediments and have even created Holocene sediments. Moreover, recorded data have shown the occurrence of various earthquakes some of which are up to magnitude of 5.
In this study, ETM++ Landsat satellite images were used to carry out the morphologic study of the area. According to the results, contrary to the belief that Yazd is a safe city, the findings are indicative of the fact that Yazd has an active regime. Based on the analysis of the satellite images, there are four faults with NW-SE trend in the north-eastern part of Yazd city. These folds have cut Holocene sediments and have outcrops and are considered active faults of the area. The detected folds have led to morphogical changes of the earth, in a way that in the area around the fold (1) with a N48W trend, a tectonic pool has come into existence. The other detected folds have cut the trend and moved the upper and lower stream due to the uplifting and changes in the topography of the area.
The fold with a N39W trend is located near Yazd city in the form of an anticline. It can be a threatening factor for Yazd city. This fold has moved the southern alluvial fans in the southern cline with a dip of 9. The third fold which is composed of a series of consecutive anticline and syncline have strongly affected Neogene and Quaternary sediments is one of the most important threatening zones for Yazd city in terms of tectonic activities. Moreover, the earthquakes which have occurred in the margin of these folds can be directly accounted for by these young movements which are one of the most important reasons for activity of the area
