Geomorphology
mojgan entezari; shokoh Esteki; Hamide Gholamhaydari
Abstract
A major cause of landslide and relevant losses and fatalities is inappropriate land management, especially in mountainous areas and valleys. In this study, risk-vulnerability superimposed model was used to investigate the probability of occurrence of fatal landslides in Tarom Watershed. The risk-vulnerability ...
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A major cause of landslide and relevant losses and fatalities is inappropriate land management, especially in mountainous areas and valleys. In this study, risk-vulnerability superimposed model was used to investigate the probability of occurrence of fatal landslides in Tarom Watershed. The risk-vulnerability superimposed model has been formulated to evaluate the landslide risk and vulnerability. These factors include topography, geology, number of streams, rainfall, frequency of faults, land use, density of roads, population density, and construction density, which were considered and analyzed in the present model. According to the model output (i.e., risk-vulnerability map), it was figured out that the eastern and northeastern parts of Tarom Watershed are exposed to highest levels of risk and vulnerability. That is, occurrence of a fatal landslide with financial losses is more probable in these areas, as compared to other parts of the watershed. Results of the present research showed that 17%, 35%, 23%, 16%, and 9% of the entire watershed area were classified as being exposed to very low, low, moderate, high, and very high risk-vulnerability levels, respectively. Advantage and superiority of this model over other models and methodologies for landslide study is simultaneous consideration of landslide occurrence risk and vulnerability of the study area to the landslide, making it capable of determining the areas of higher probability of fatal landslides with financial losses.
Geomorphology
Mousa Abedini; biuk fathalizadeh; Masomeh Rajabi
Abstract
Introduction
When a natural process threatens human life or property, it is called natural hazard. Disasters’ statistics have shown that their effects are, considerably, increasing all over the world. Most of such disasters originate from geomorphological events. In fact, natural disasters have ...
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Introduction
When a natural process threatens human life or property, it is called natural hazard. Disasters’ statistics have shown that their effects are, considerably, increasing all over the world. Most of such disasters originate from geomorphological events. In fact, natural disasters have been a global concern and most of them have mainly been geomorphological. Hence, developing countries, in particular, are deeply influenced by such disasters. One way of decreasing damages caused by natural disasters is identification of disaster-prone areas and prevention of their development in such areas relying on land use planning. In this research, geomorphological hazards of flood, landslide and neotectonics were investigated in Zonouzchay catchment. The catchment in an area of 323 square km has been located in political-administrative zone of Marand county.
Methodology
The aim of the present study is to evaluate geomorphological hazards in Zonouzchay catchment through preparing zoning maps of flood, landslide and neotectonics hazards. Digital evaluation model images of height (DEM), geological maps and sentinel satellite images are the most important data used in the present study. For preparation of flood and landslide hazards’ map in Zonouzchay catchment, ten variables and effective parameters on flooding and flood spreading were combined in GIS environment. These variables are considered for zoning flooding hazard factors such as height, slope, convexity of the land surface, valley depth, lithological units, drainage density, distance from the main streams, height of the runoff, use and vegetation. For zoning landslide occurrence risk, the above mentioned variables (except for stream height, drainage density and valley depth) were used along with the three variables of distance from fault, slope direction and rainfall. ANP model in GIS was used in order to combine effective variables on flooding risk and landslide in Zonouzchay catchment. Moreover, zoning relative neotecnic activities for the underlying area was conducted by using relative tectonic activity index (Al Hamdouni, et al, 2008). Relative tectonics activity index (Iat) is developed by combination of other indexes. The index classifies the perspectives in four classes of relative tectonic activities:
Class 1: too high tectonic activities with values 1 < S/n < 1.5
Class 2: high tectonic activities with values 1.5 < S/n < 2
Class 3: medium tectonic activities with values 2 < S/n < 2
Class 4: low tectonic activities with values S/n < 2.5
Results and Discussion
Zoning Relative Tectonic Activity
Results of Iat index-basedzoning indicate that neotectonic activities in Zonouzchay catchment are, generally, medium to relatively weak. Field observations also indicate that erosive processes (in spite of resistant formations) are predominate in the study area. Lack or rare dispersion of neotectonic landforms, retreat and destruction of mountain fronts and widening of the valleys are among the reasons, which show relative weakness of the active tectonic in Zonouzchay catchment. The main part of the morpho-tectonic landforms of the catchment is in line with Zonouz-Harzand fault. For most of the sub-catchments Iat values are in classes 3,4, which shows average to weak status of the relative active tectonic in the catchment.
Zoning Flood Event Risk
ANP model-based results indicate that from among the employed variables, slope, distance from river and land surface convexity are, relatively, the most important variables with coefficients 0.23, 0.19 and 0.16. Findings of the study indicate that about 4% of Zonouzchay catchment area is in too high risk class, 7.4% in high risk class, 8.3% in medium risk, 21.7% in too low risk class and 58.6% is in too low risk class. Almost all upstream parts of the study catchment are in low risk to high risk classes. In the middle parts of the study catchment, flood zones are mostly bounded to two main valleys of the catchment. Width of the valleys has increased in different periods and, consequently, flood plains have been formed in the basin of such valleys. Some parts of Miyab and New Harzand villages have been located in this geomorphologic position. In the downstream parts of the catchment, width of Zonouzchay has increased considerably and also the two main streams of the study catchment join each other in this part. Presence of low slope lands, low relative height, adjacency to the main rivers, lower values of convexity index, higher density of drainage and the valley depth are considered as the most important effective factors of this part of the catchment in terms of flood event.
Landslide Risk Zoning
According to the results of ANP model, the three variables of slope with coefficient of 0.24, lithology with coefficient of 0.22 and rainfall with coefficient of 0.16 have the key influence on landslide occurrence in the study area. Hence, about 16.6 % of the catchment area is in too low risk class, about 38.1% is in low risk class, about 23% is in medium risk class, 15.8% is in high risk class and finally 6.5% is in too high risk class. Spatial distribution of the risk classes indicates concentration of high risk and too high risk classes in the middle arts of the study catchment. This can be related to various factors. Maybe, the most important reason is related to presence of geological formations prone to landslide and appropriate slopes for occurrence of such geomorphological process. In fact, in the middle parts of the study area dominance of slope 10%-40% , presence of high alluvial terraces , also occurrence of Marens , conglomerate formulations with Maren interlayers and dispersion of Flysch type have provided appropriate conditions for landslide.
Conclusion
Results of geomorphological indexes indicate that considerable part of anomalies of this index are originated from lithological differences of the area. Moreover, active tectonic zoning of the area shows relative weakness of neotectonic processes and movement of the area’s faults along with dominance of erosive processes. Regarding flood occurrence risk, results of ANP model indicated that the variables of slope, distance from river and convexity of the land surface have higher importance in flooding. From flooding occurrence perspective, about 4% of Zonouzchay catchment is in too high risk class and 7.4% is in high risk class. The dangerous zones are accordant to valleys’ bed of the two main streams of the catchment and hence, some parts of the residents in these valleys are exposed to destructive floods. Finally, based on results of ANP model results, three variables of slope, lithology and rainfall have higher importance in probability of landslide occurrence in the study area. About 16% of Zonouzchay catchment is in high risk class, and 7% of it is in too high risk class of landslide. Landslide occurrence in the middle parts of the catchment is highly expected due to a set of conditions such as vulnerable slope and geological formations.
Geomorphology
Leila Khodaei Geshlag; shahram roostaei; Davod Mokhtari; Khalil Valizadeh Kamran
Abstract
Introduction Risk management and landslide assessment begin with a comprehensive identification and monitoring of their movements and mapping them, which can be used as a basis for achieving knowledge about their spatial and temporal distribution. The integrated vision of the radar remote sensing images ...
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Introduction Risk management and landslide assessment begin with a comprehensive identification and monitoring of their movements and mapping them, which can be used as a basis for achieving knowledge about their spatial and temporal distribution. The integrated vision of the radar remote sensing images has made them a powerful tool for preparing distribution maps, assessing the risk of landslides, and evaluating the instabilities reoccurring at various time intervals. Therefore, this study aimed to identify, monitor, and measure the extent to which the region is at the risk of slope instabilities in the period of 2009-2011 in the Ahar-Varzeghan region in the Ahar Chay heights using the Interferometry Synthetic Aperture Radar (InSAR) technique. Data and Method The studied area is a part of Ahar Chay watershed with an area of 1593 km2, which makes it the largest watershed in the East Azerbaijan province. The said area has an east longitude of 35´ 46° to 10´ 47° and north latitude of 20´ 38° to 45´ 38°. This area is located on northern slopes at an altitude of more than 2730 m, and in the Alpaut and Chaligh areas with an altitude of less than 1260 m. Various types of data were used in this research, including radar imagines, ENVISAT-ASAR, and data captured by Global Positioning System (GPS) in field research. Besides, topographic maps of 1.25000 associated with the country's land surveying organization and geological maps of 1:250000 related to the country's geological and mineral exploration organization were used to examine the area's geology and morphology. Besides, SAR scape ENVI4.8 and Arc/GIS software environments were used to prepare and process radar images, and provide the displacement maps associated with the landslides. INSAR is a remote sensing technique developed to study the earth's surface movements in the 1992 Landers, California earthquake. When this technique is adopted, two or more SAR images are used to generate a digital elevation model or prepare a map of the movements of the earth's surface. Also, this technique measures the phase difference between two different waves, and this phase difference is attributed to the change in the distance between the sensor and the earth target or the movements of the earth's surface. SAR images show the movements of the earth's surface in the direction of the satellite's line of sight. However, SAR images can be used in both ascending and descending modes, which enable them to measure the earth's surface movements in three directions: vertically, from the north, and east. The following steps must be taken to measure the movements of the earth's surface and/or develop a digital elevation model using the InSAR technique: SAR image formation: - Interferogram generation - Ambiguous phase extraction - Phase recovery in the generated interferogram - Elimination of the effect of the topographic phase on the interferogram - Displacement phase extraction Results and Discussion The InSAR technique has been used in this study to identify the range of slope instabilities and the rate of displacement of unstable landslides. Based on the research findings, radar images and differential interferometry processing methods could potentially identify unstable active areas and calculate the rate of displacement. In this study, the results of the ASAR radar image processing were used to calculate the rate of displacement from 2009 to 2011. Figure 9 showed the displacement rate for the period of 2006-2011. It should be noted that positive and negative numbers in this figure indicated the rate of upward and downward movements, respectively. According to this figure, the highest and lowest rates of downward movements were associated with 2009 and 2011, respectively. In other words, the rate of downward movements had decreased by 2011. However, the rate of upward movement in the region was the highest for the years 2009 and 2010. Also, the lowest rate of upward movement recorded for this area was in 2011. Conclusion The present study utilized the InSAR technique to identify the range of landslides and to estimate the displacement of unstable landslides. The results of this study showed that radar images and differential interferometry processing methods could potentially identify unstable active areas and calculate the rate of displacement. In this study, the results of the ASAR radar image processing were used to calculate the rate of displacement between 2009 and 2011. Then, the validity of the results of the InSAR technique was measured by adapting the displacement maps to field operations and Google Earth. According to the research findings, the highest rate of fall or downward movement occurred in approximately 8 cm in the southern areas. Moreover, the highest rate of elevation or upward movement occurred in about 5 cm in the east northern areas in 2009. The highest rate of falls in this year was associated with areas with old landslides, among which the villages of Depigh, Nasirabad, and around Sariaraghan were more affected than other areas. These instabilities in the village of Depigh were mostly located around the bed of the Ahar Chay river, in a way that severe landslides in this area caused enormous rocks to accumulate on the surface of the river bed.
Geomorphology
sayyad asghari; delnya palizban; Hadi Emami; ehsan ghaleh
Abstract
Introduction Landslide is a term that encompasses a variety of amplitude motions and causes the movement of a mass of material in the slopes. And creep is classified. Natural slope instability is one of the geomorphological and geological phenomena that plays an effective role in deforming the ...
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Introduction Landslide is a term that encompasses a variety of amplitude motions and causes the movement of a mass of material in the slopes. And creep is classified. Natural slope instability is one of the geomorphological and geological phenomena that plays an effective role in deforming the earth's surface. Identifying areas with potential for landslides and their zoning is one of the key steps in managing environmental hazards and reducing the damage caused by this phenomenon, because this phenomenon causes financial and human costs, soil and land degradation and increased sediment production at the basin outlet. It becomes. Iran with its predominantly mountainous topography, high tectonic activity and seismicity, diverse geological and climatic conditions, has the most natural conditions to create a wide range of landslides. The purpose of this study is to zoning the risk of landslides on the Sarab-Nir road. In this research, two models of network analysis and fuzzy logic are examined and evaluated. It is hoped that eventually, by preparing a landslide risk zoning map, it will be of great help to planners and managers in order to reduce potential damages and find safer locations for development, construction and road construction. Methodology Sarab-Nir road is located between East Azarbaijan province and Ardabil province and is a communication route between these two provinces, whose geographical coordinates are 37 degrees and 94 minutes to 38 degrees and 03 minutes north latitude and 47 degrees and 53 minutes to 48 degrees and 01 minutes. It is east longitude. In this study, network analysis model was used to determine areas prone to fall and zoning. In order to better understand the causes of landslides and also to organize the research in the field, the study area was visited and 15 geographical points from different areas of the study area were recorded. The geographical location of the points prone to fall was also recorded with GPS. Then, according to the network analysis model, information layers were prepared in ArcGIS software. The information layers for landslide risk zoning are: fault, slope, slope direction, distance from road, and distance from waterway, land use, geology (lithology), precipitation, altitude and vegetation. The elevation file or digital model of the elevation of the area was prepared with an accuracy of 30 meters from the USGS site and the desired DEM is a digital file obtained from the ASTER sensor and according to this DEM, the information layer such as streams, slope and direction The slope was obtained. Results and Discussion Four maps have been developed to investigate landslide hazards, which are rainfall, slope, elevation and land use layers. After creating information layers in order to prepare the final landslide hazard map, fuzzy information layer maps were created. In this study, in order to determine the effect of different classes of criteria on landslide sensitivity zoning, the layers are based on the type of performance of each in the landslide event using fuzzy membership functions in the range of zero to 1 fuzzy. Were made. The results obtained from the information layers and finally the landslide hazard map show that altitudes of more than 2000 meters have the highest share of landslides, and altitudes of 1400 meters have been significant landslides due to the instability of the slopes against Climatic and environmental factors. Also, most of the landslides occurred at a distance of 3 to 6 km from the faults, which shows the importance of faults against landslides. About 40% of landslides occur in very high-risk classes. This indicates that the model has a high capability in predicting landslides. It is necessary to explain that most of the landslides occur in the area of Saein pass, which have very favourable conditions for the occurrence of range movements that start from 25 km of mirage and continue for a distance of 15 km of Nir. Conclusion Factors such as slope, precipitation and geology play a more important role in landslides than other factors. Slopes of 60 to 80% have the greatest impact on landslides, which are more pronounced at altitudes above 2000 meters. Therefore, altitudes above 2000 meters have the most landslides. Also, due to the direct relationship between altitude and climatic fluctuations in these altitudes, the amount of precipitation is higher and, of course, has a great impact on the occurrence of landslides. In these areas, vegetation is at a minimum and due to the cold region, the vegetation in these areas is very small, which prepares the conditions for landslides and due to the presence of sedimentary formations such as sandstone, Siltstone mudstone with tuff interbreeds in the area, the conditions for landslides have become more prone and because these formations lose their stability sooner and are strongly influenced by physicochemical factors, they are more prone to landslides than other formations. To be. According to the results, the low risk floor with the highest value, 405.44 square kilometers, occupies approximately 30.87 percent of the area, but the very high risk floor with 288.2 square kilometers and the high risk class with 23.23 square kilometers. , Occupy a total of 37.25% of the area of risk classes.
Geomorphology
shahram roostaei; christineh jananeh
Volume 23, Issue 70 , March 2020, , Pages 169-188
Abstract
Landslides and slope instabilities are among the important natural hazards, which cause human and financial casualties and loss of economic resources every year. These hazards mostly occur in natural slopes or those manipulated by human. Landslide hazard zonation is one of the methods by which, areas ...
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Landslides and slope instabilities are among the important natural hazards, which cause human and financial casualties and loss of economic resources every year. These hazards mostly occur in natural slopes or those manipulated by human. Landslide hazard zonation is one of the methods by which, areas prone to landslide occurrence can be determined and plannings can be done using the obtained zonation maps to reduce the casualties. The aim of this contribution is to study landslide hazard zonation within the Baleghluchai watershed in NW Iran. First, the main factors including the slope and its direction, geology, soil, climate, distance from the road and river and land usage were determined. The method of current investigation was Fuzzy AHP in the GIS environment, based on which, after preparing data layers using the above-mentioned parameters and giving weights to them in the GIS environment, the landslide potential map, as well as classification was carried out by Fuzzy AHP method. Results showed that the largest part of the watershed (32.21%) has low landslide potential, while about 13.5% of it has very high potential. Areas with very high and high landslide potential (327.39 km2 area) are mainly located in the northwest of the watershed, with some small areas distributed in the south and east, while areas with very low and low potential (504.06 km2) are mainly found in the central to northwestern and southern parts of the watershed.
Geomorphology
musa abedini; shahram roostaei; Mohammad Hossein Fathi
Volume 22, Issue 66 , January 2019, , Pages 187-205
Abstract
Diagnosis and classification of landslides is a critical need in the risk analysis before and after the disaster. And primarily through land surveying or traditional interpretation of images was done. In this paper to identify and classify types of object-oriented approach landslide has been paid. The ...
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Diagnosis and classification of landslides is a critical need in the risk analysis before and after the disaster. And primarily through land surveying or traditional interpretation of images was done. In this paper to identify and classify types of object-oriented approach landslide has been paid. The data used in this study consisted of false color images obtained from satellite data Resourcesat-1 with spatial resolution of 5.8 meters and digital elevation models with 2.5-meter resolution satellite image of 10 meters of Cartosat-1 was used. This method was used for the North West basin and then used without further reforms in the eastern part of the basin. A total of three sliding using this method accurately identified 71.11% and 91.4% classification accuracy has been detected. In this way, the landslide early detection of high accuracy and speed, hence has great potential to assist in risk analysis, disaster management and decision making process after the earthquake or heavy rainfall, can be used related entities, including crisis management headquarters, natural resources and watershed institutions.
Geomorphology
Ebrahim Asgari Kalajahi; Fatemeh Namakchi; Abdolreza Vaezi Hir
Volume 20, Issue 56 , August 2016, , Pages 19-38
Abstract
Landslide is one of the natural hazards which affects mountainous areas and destroys residential areas, farms and basic facilities each year. In addition to the damages caused by landslides on roads in towns and villages, the natural environments are also affected by soil erosion. The study area with ...
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Landslide is one of the natural hazards which affects mountainous areas and destroys residential areas, farms and basic facilities each year. In addition to the damages caused by landslides on roads in towns and villages, the natural environments are also affected by soil erosion. The study area with an area of about 80,000ha is located in the west of Khoy city, northwest of Iran. Some landslides have occurred on the southern slopes which verge on the roads and frequently damage the main road, Iran-Turkey railway and several villages, such as Gougerd and upper Kalt village. Due to the proximity of the study area to the main roads and residential areas and the existence of several historical mass slides, evaluation of landslide hazard and preparing a risk map is necessary. In this research, the potential landslide zoning map was developed by evaluation of each parameter influencing landslide including lithology, slope geometry, geological structures, relative elevation, land use and coverage and ground-water. Final zoning map was produced through overlaying of the maps developed by scoring of the mentioned parameters. The study area was divided in to 5 zones from potential landslide view of point, including safe, low, medium, risk and very high risk zones. About 23 and 5.6 percent of the total area are subjected to high risk and very high risk landslide hazards, respectively.
seayed asadollah Hejazi
Volume 18, Issue 50 , February 2015, , Pages 135-152
Abstract
This article aims to evaluate sensitivity of Goijabel basin lands in landsliding based on GIS and AHP. The main reason for selection of this basin for research is to observe the current landsliding in the region by the author and environmental preservation attitude of the authors. This basin is one of ...
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This article aims to evaluate sensitivity of Goijabel basin lands in landsliding based on GIS and AHP. The main reason for selection of this basin for research is to observe the current landsliding in the region by the author and environmental preservation attitude of the authors. This basin is one of the sub-basins of Aharchi in area of 7406 Hectares with geographical statues of 46,47,21/26 to 46,56,53/64 east longitude and 38,21, 42/13 to 38,27,39/04 north latitude. The criteria selected for analysis of landsliding sensitivity in the study basin involve nine parameters (slope, aspect, height, lithology, fault, road, landuse, precipitation and main water ways) extracted from basic maps, field studies and spot satellite images and their primary valuation was conducted by using GIS techniques in five layers relative to the effect of each measure on incidence of landsliding. Then pair comparison of the layers was carried out by using Mariyoni attached program (AHP extension) and final map of the land sensitivity in landsliding was extracted. The results of landsliding sensitivity analysis in Goijabel basin showed that the most effective factor in land sliding is lithology with weight of 0.3113 according to the highest weight and then the height with minimum weight of 0.0178 is the criterion with lowest effect in landsliding. Also the analysis of landsliding danger in the study basin shows that endangered lands with high sliding capability involve 1222 ha which cover %16.5 of the total regions.
Aghil Madadi; Behnam Noee; Abazar Esmali
Volume 17, Issue 43 , October 2013, , Pages 307-326
Abstract
Identifying of impact factors in occurrence landslides of and hazard zoning is basic instrument for controlling this Phenomenon. Aim of this research is the assessment of the effective factors in landside occurrence and mapping it by using landside index model (LIM). For above pepouse", 11 important ...
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Identifying of impact factors in occurrence landslides of and hazard zoning is basic instrument for controlling this Phenomenon. Aim of this research is the assessment of the effective factors in landside occurrence and mapping it by using landside index model (LIM). For above pepouse", 11 important factors in mapping of landslide were evaluated and recognized by field working. Then landslide hazard zoning was performed by landside index model on the basis of 11 factors weight. After calculating of these factors (altitude classes, slope gradient, slope orientation, network dantsity, distance from river, distance from road, lithology, distanse from fault, vegetation cover, land use, annul rainfall and soil hydraulic group), final map was commutated from algebraic overlaying of 11-layers and there by final weight map was obtained. Study and analysis of 11-raster map, and important factors in Givi Chay watershed landslides using LIM Method showed that area with annual 375-405 mm precipitation had more influence in landslide occurrence. Also altitude classes between 1512-1927m area with low vegetation, area with high permeable soils and slopes with east and northeast orientation higher influence in occurrence.
Alireza Ildoromi
Volume 16, Issue 37 , November 2011, , Pages 1-33
Abstract
The watershed area of Ekbatan dam with an area equal to 22155 ha has located in the northern front of Alvand mountainous in Hamadan province and in a distance of 10 km from Hamadan. In this area landslides have a very specific morphological role and have caused the bareness of the skirts. According to ...
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The watershed area of Ekbatan dam with an area equal to 22155 ha has located in the northern front of Alvand mountainous in Hamadan province and in a distance of 10 km from Hamadan. In this area landslides have a very specific morphological role and have caused the bareness of the skirts. According to the field examinations and air photography seven cases of land slides have been registered which had specific dispersion in the region. Examinations show that most of the landslides are shallow and over the surface. Collection of surface sediments mostly of sands and gravels in some regions specially depositing pits which are suitable places for the creation of slides. Increase in the stress and increase in the cut stability under different factors cause increasing cuts and land slides in the said pits. Quantity analysis of the slides through morpho metric indicators such as depth indicator, expansion, narrowness, displacement etc. are the representatives of surface slides. Almost all of the landslides in the region are in equilibrium which show the main part of the stable materials from the first site. The increased amount of D/L ratio represents the side expansion and the width change shape of the materials and the estimation of L/D, W/D, and L/W show the direct effect of the slope in creation of landslides. Results showed that changes in the length of slides have been severe and it is more severe in case of length change which with characteristic represents a surface equal to 26668.76 2m and a volume equal to 60517.7 3m, which shows a surface equal or more that 44 cm. In the level of the region they are erupted through the landslides. Therefore slides have an important role in displacement of the materials in the skirts and creating stability and also by creating sediment and leaving it to the rivers of dam region causes the transition and gathering of sediments in the dam and reduction of the Ekbatan dams life.
