Hydrogeomorphology
Mohammad Hossein Rezaei Moghaddam; Davoud Mokhtari; meysam skandarialni
Abstract
Hydrological models are an effective tool for managing water resources as well as water balance components among research works. Today, basin hydrological models have been developed, but choosing the right model to simulate a specific basin has always been a challenge. Therefore, it is necessary to choose ...
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Hydrological models are an effective tool for managing water resources as well as water balance components among research works. Today, basin hydrological models have been developed, but choosing the right model to simulate a specific basin has always been a challenge. Therefore, it is necessary to choose a model that can simulate the hydrological processes with the simplicity of the structure and using minimal factors. Northwest Iran was simulated by AWBM and SWAT models. The AWBM model is an integrated model that simulates the runoff in catchment areas using two variables, rainfall and evaporation, and on the other hand, the SWAT model is a continuous and semi-distributed model that simulates hydrological processes using the physical characteristics of the basin (soil, land use, slope) as well as several water and meteorological information such as rainfall, temperature. The results of runoff simulation in the calibration and validation periods were evaluated using two Nash Sutcliffe statistical indices (NSE) and R2 coefficient of determination. By comparing the results of the statistical indicators used in the study, it was found that the SWAT model has better results in the simulation of monthly runoff in the validation and validation periods.
Geomorphology
Davoud Mokhtari; Mohammad Hossein Rezaei Moghaddam; diana dortaj
Abstract
Tectono-karst processes play an important role in the formation and change of landforms. Some areas, such as Zagros in Fars province, are affected by tectono-karst activities due to being in a tectonically active area and also having karstic formations. Due to the importance of studying landform changes ...
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Tectono-karst processes play an important role in the formation and change of landforms. Some areas, such as Zagros in Fars province, are affected by tectono-karst activities due to being in a tectonically active area and also having karstic formations. Due to the importance of studying landform changes in different planning, in this research, the analysis of tectono-karst processes in the formation and expansion of the transverse valleys of Zagros, Fars, from the range of Avaz to Karmostaj has been done. In this research, Sentinel 1 radar images, SRTM 12.5m high digital model, 1:100000 geological map of the region and hydroclimatic information of the region are used as the most important research data. The most important tools used in the research were ArcGIS and GMT. This research has been carried out in two stages according to the desired goals, in the first stage, the tectonic status of the region has been evaluated using the SBAS time series method, and in the second stage, using the Fuzzy Logic-AHP integrated model, to the potential The measurement of areas prone to the development of karstic processes has been discussed. The results obtained from the SBAS time series method have shown that some of the transverse valleys of the region are subsiding in comparison to their downstream regions, and this problem has caused a decrease in the height difference, a decrease in the speed of runoff, creating the necessary opportunity for erosion and dissolution, and in The result is the transverse development of these valleys. Also, based on the results, all the transverse valleys are located in the category with high or very high potential for the development of karstic processes, which indicates the role of karstic processes in the formation of transverse valleys in the region. The total results of this research have shown that the formation and development of transverse valleys in the studied area were affected by tectokarst factors.
Hydrogeomorphology
Fariba Karami; Davoud Mokhtari; Farnush Ahmadi
Abstract
The aim of this study is to estimate the rate of soil erosion and its relationship with landforms of Zonuzchay catchment in Marand city. In this study to estimate the rate of soil erosion and sediment production, the modified global model of soil loss (RUSEL), geographic information system (GIS) and ...
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The aim of this study is to estimate the rate of soil erosion and its relationship with landforms of Zonuzchay catchment in Marand city. In this study to estimate the rate of soil erosion and sediment production, the modified global model of soil loss (RUSEL), geographic information system (GIS) and remote sensing (RS) was used. To implement the model, rainfall erosivity factors (R), soil erodibility factor (K), slope length-gradient factor (LS), support practice factor (P), and cover-management factor (C) in Arc GIS environment calculated and Then a soil erosion map was drawn. Topographic position index (TPI) was used to classify and map the landforms of the basin. Then, the role of different landforms in relation to soil erosion rates was investigated by combining relevant maps. The results showed that the values of soil erosion in Zonuzchay basin vary between 0 and 50.20 tons per hectare per year. Valleys and cuts located on heights and slopes have the highest rate of erosion and low-slope domains and flat areas and plains include areas with low and very low erosion. In Zonuzchay basin, soil erosion is mostly on the builders of Flysch type deposits, red and gray conglomerates with Marny layers and alluvial terraces. Investigation of regression relationships between (RUSLE) model factors and soil erosion of Zonuzchay basin showed that the slope length-gradient factor has the greatest effect in calculating the rate of erosion of Zonuzchay basin. .
Geomorphology
somayyeh moazzez; Davoud Mokhtari; Mohammad hossein Rezai Moghadam
Abstract
AbstractAlluvial fans are among the areas prone to geomorphological hazards. One of these hazards is liquefaction, which the main purpose of this research was to investigate this phenomenon in the surface of the alluvial fan. The FUZZY-VIKOR combined model and GIS technique were used to prepare the liquefaction ...
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AbstractAlluvial fans are among the areas prone to geomorphological hazards. One of these hazards is liquefaction, which the main purpose of this research was to investigate this phenomenon in the surface of the alluvial fan. The FUZZY-VIKOR combined model and GIS technique were used to prepare the liquefaction risk potential map. The used parameters in this research were: slope, depth of underground water, type of soil and seismicity. The information layers of each of these parameters were prepared in the ArcGIS software environment. Next, the fuzzy model was used to standardize the layers. At the end, the weighting of the parameters was done by Vikor method. . The results of weighting the parameters by Vikor method showed soil and depth of underground water have obtained the highest importance coefficient with the weight of 0.442 and 0.236 respectively. The final map was prepared by overlapping the layers and multiplying the final weight of the criteria in each layer in 5 classes from very low to very high potential. The final map was prepared by overlapping the layers and multiplying the final weight of the criteria in each layer in 5 classes from very low to very high potential. The results of examining the area of each risk class showed that 0.28% of the area is in the very high class and 70% is in the high class in terms of the risk of liquefaction. Mainly, the areas with high risk potential are located in the downstream parts of the region.
Hydrogeomorphology
Abolfazl Faraji mondared; shahram roostaei; Davoud Mokhtari
Abstract
Due to their geomorphological characteristics, alluvial fans are part of the high flood risk area. Placement of human phenomena in flood zones is a factor that intensifies the instability of currents. For this purpose, in this research, we applied the location of human phenomena in the geographical space ...
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Due to their geomorphological characteristics, alluvial fans are part of the high flood risk area. Placement of human phenomena in flood zones is a factor that intensifies the instability of currents. For this purpose, in this research, we applied the location of human phenomena in the geographical space of Pardisan in the flood zone with an applied-experimental method. To achieve this goal, the HEC-RAS-6 hydraulic model has been used as a working tool. Due to the size of the area, the area was divided into 15 sub-basins. First, the sub-layers of rivers and floodplain network were extracted, then human phenomena in the studied space were extracted and located on the RAS background map. Then the measured data and values were considered and implemented in the model. By locating the phenomena and considering the conditions of the alluvial fan flood, it was determined that the 100-year-old flood in the area of railway and communication lines, stairs in the west of Pardisan, west side of Payamnoor University, upstream of Pardisan town and also agricultural lands, has a high vulnerability rate. In general, despite the newly established Pardisan town, urban design and subsequent study and modification of the route did not match the geographical features of the region and the prospect of instability has prevailed in the geographical space of the area. It is suggested that for the future development of the city, the flood route be improved and monitored upstream to maintain environmental sustainability.
Hydrogeomorphology
Davoud Mokhtari; Amir Heshmati
Abstract
Knowing the subsurface structures is one of the ways to access underground resources, and knowing the characteristics of alluvial sediments is very important for exploitation, management and control of underground water. Shahryar plain located in the west of Tehran city and south of central Alborz, which ...
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Knowing the subsurface structures is one of the ways to access underground resources, and knowing the characteristics of alluvial sediments is very important for exploitation, management and control of underground water. Shahryar plain located in the west of Tehran city and south of central Alborz, which supplies an important part of Tehran city's drinking water, is covered with Quaternary alluvium. The purpose of this article is to determine the thickness of these alluviums. There are different geophysical methods to estimate the thickness of different layers of the earth to determine the characteristics of alluvial deposits, including the type, depth, thickness, etc., of this plain, the data of electric soundings includes: 12 profiles and 186 sections, received from the regional water organization, geological maps, and data DEM used. After checking and validating the data, by choosing the normal kriging interpolation method with exponential variogram, the alluvial thickness and topography maps of the underlying layers include: alluvial thickness map, evaporite sediment surface topography, tuff and igneous rocks topography, The topography of the bedrock of the region, the thickness of evaporite sediments and the topography of the conglomerate surface of the region were preparedin in GIS with the highest accuracy. Then horizontal and vertical characteristics of these deposits were investigated. The results showed the maximum thickness of the alluvium is up to 350 meters in the center And near the edge of the plain, the thickness of alluvium decreases so that it is about 10 meters in the west and southwest.
Geomorphology
Reza Abbasian valandar; shahram roostaei; Davoud Mokhtari
Abstract
The Tamtaman area is located between 37◦38/00//-37◦44/00//north and 44◦40/30//-44◦59/30// east in northwestern Iran, approximately 15 km northwest of Urmia. This study aims to identify and zoning the potential development of karst in the area of Tamtaman cave in west Azerbaijan province using ...
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The Tamtaman area is located between 37◦38/00//-37◦44/00//north and 44◦40/30//-44◦59/30// east in northwestern Iran, approximately 15 km northwest of Urmia. This study aims to identify and zoning the potential development of karst in the area of Tamtaman cave in west Azerbaijan province using the AHP method. In this study, the information layers of lithology, tectonics, topography, slope, aspect, hydrology, land use, and climate have been considered as factor maps. The above layers have been called to extract the karst potential model in the GIS environment. Different information layers were classified as Criterion maps by applying expert judgment and assigning the weight of each layer in Expert Choice software and field visits. Finally, according to the obtained weight, the karst development zoning map in the Tamtaman area was obtained. The results obtained in this region exhibited a total area, of 6.68% within the very poorly developed class, 15.64% in the less developed class, 42.50% in the normal developed class, and 35.18% in the developed floor are located. The results show that in the Tamtaman region, the lithological and tectonic factors have the highest weight and are the most important factors controlling potential karst growth, while the land-use factor has the least impact on karst formation.
Mohammad Hossein Rezaei Moghaddam; Davoud Mokhtari; Nasrin Samandar
Abstract
Land use change is one of the important factors in changing the hydrological flow, basin erosion and biodiversity destruction. Therefore, knowing the effect of land use change on discharge and suspended load is an inevitable necessity. The main purpose of this study is the efficiency test of the model ...
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Land use change is one of the important factors in changing the hydrological flow, basin erosion and biodiversity destruction. Therefore, knowing the effect of land use change on discharge and suspended load is an inevitable necessity. The main purpose of this study is the efficiency test of the model and its usability as a simulation of the process of land use change on discharge and sediment is from the soil and water assessment model (SWAT) and SUFI2 program. Model simulation was performed for 29 years from 1987 to 2015, the first 5 years of which were selected for model calibration and the last 5 years for model results validation. Four statistical indices, r_factor, P_factor Nash-Sutcliffe (NS) and coefficient of determination (R2), the ratio of squared root-to-standard deviation (RSR) and the percentage of skewness (PBIAS) were selected monthly to evaluate the model. The accuracy of monthly simulation using NS evaluation index in the calibration and validation stage for flow and suspended load is equal to 0.65 and 0.49, respectively. The results of the study were considered acceptable according to the interpretive domains used in previous studies and indicate the satisfactory efficiency of the SWAT model in simulating the components of the impact of land use change on sediment and discharge in the Ojan Chay Bostanabad watershed. The results showed that the height of surface runoff increased by 1.15 mm and the sediment concentration increased by 1.5 tons per hectare per year.
Mohammad Hossein Rezaei Moghaddam; Davoud Mokhtari; Majid Shafieimehr
Abstract
Floods are one of the most common natural hazards, causing significant loss of life and property each year. The purpose of this study is to determine the risk areas of floods in Shahr Chai Miyaneh watershed. To implement this model, different layers such as slope, aspect, elevation, distance from river, ...
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Floods are one of the most common natural hazards, causing significant loss of life and property each year. The purpose of this study is to determine the risk areas of floods in Shahr Chai Miyaneh watershed. To implement this model, different layers such as slope, aspect, elevation, distance from river, river density, land use, vegetation, lithology, rainfall and soil were used. The final analysis and modeling was performed using the Vikor model. The results showed that rainfall, slope and distance from the river have the greatest impact on the occurrence of floods in this watershed. Also, according to the obtained results, 5.2 and 1021.7 square kilometers, respectively, are located in a very high-risk and high-risk area. Dangerous and very dangerous areas are mainly located along the main river and mountainous in the steep logic. Due to the high slope and height of the region, it plays an effective role in the amount of runoff and flow peak floods. Also, in the catchment area of Miyaneh Chai city, 2.2, 27.2, 1099.6, 1021.7 and 10.2 square kilometers, respectively, are in a very low risk, low risk, medium, high risk and very high risk area.
Fatemeh khodaei; shahram roostaei; Davoud Mokhtari
Abstract
1-IntroductionThe phenomenon of desertification refers to the process of destruction and devastation of natural ecosystems in arid, semi-arid and semi-humid arid regions, which leads to a decrease in biomass production and the emergence of soil destruction effects or erosion (Ekhtesasi et al., 2011: ...
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1-IntroductionThe phenomenon of desertification refers to the process of destruction and devastation of natural ecosystems in arid, semi-arid and semi-humid arid regions, which leads to a decrease in biomass production and the emergence of soil destruction effects or erosion (Ekhtesasi et al., 2011: 14). Desertification occurs due to natural factors such as climatic variables and human activities (Binal et al., 2018: 10), (Collado et al., 2002: 121) and its impact on ecological processes is very high and complex, such as negative effect on plant characteristics (such as biomass, lands density and area covered by vegetation), soil biodiversity loss and reduction soil fertility, change in landscape patterns of arid areas at various geographical scales (Xu et al., 2009: 1738). Therefore, combating desertification is essential to ensure long-term soil and land exploitation in arid regions of the world. Destruction of water resources, both quantitatively and qualitatively, can lead to biomass depletion and eventually desertification. Groundwater quality is the result of all the processes and reactions that operate on water from the moment of condensation in the atmosphere until it is discharged from a well or spring.2-Methodology1-2- Study areaThe study area included part of the Urmia catchment located in the northwest of Iran with a longitude of 44”0’ to 47”0’E and latitude of 37”0’ to 38”20’N, with an area of 14.395km2. The intersection of the mountain and the plain indicates the boundaries of the study area. (figure 1). Fig (1): The study area2-2- Method of Preparing a map of desertification sensitive areas in a project entitled “MEDALUS”It was carried out by the European Commission, and the ESAS model was presented in 1999. In the Medalus method, four key criteria are evaluated: soil quality, climate quality, vegetation quality and management quality. Each criterion also has indicators that, in fact, form the layers of that criterion.In Iran, by calibrating the mentioned model, at first, the most important criteria affecting the desertification process are identified and scored based on descriptive-quantitative indicators. The score 1 is considered for the best conditions and the score 2 is considered for the worst conditions and for the average conditions the score between 1-2 is considered. In the next stage, the score of the indicators is investigated and using the geometric mean based on equation 1, the status map is calculated for each main criterion:(1) Ix = [(L1) × (L2) × (L3)…… .. (Ln)]1 / n Ix: The status related to each main criterion includes: soil status, climate status, vegetation status, erosion status, management status and groundwater status. L1, 2, …… n: Indicators under investigation for each criterionN: The number of indicators under investigation for each criterionIn the Medallus model, the desertification risk map is obtained by emphasizing the groundwater criterion according to the following equation:(2) Criterion of water resources destruction= (groundwater drop × electrical conductivity ratio × groundwater chlorine ratio × sodium absorption ratio) 1.63-Results and DiscussionAfter preparing the weighted layers, the groundwater quality map was prepared using ArcGIs software environment. According to the obtained results in the southern half and southeastern of the case study area, groundwater has low quality because the four indicators of water electrical conductivity, chlorine ratio, sodium adsorption ratio, and water table level drop ratio have the highest ratio. So that the electrical conductivity ratio in these areas is in the high class and is about (2400-4600 dS / m), the chlorine ratio is in the middle class and is equal to (500-1033 mg / l), the sodium absorption ratio is in the very high class and is about (27-92 mg /l). In these areas, the groundwater table level has decreased about 50 cm per year (figure 2). Fig (2): Desertification intensity map with emphasis on groundwater criteria based on Medalus model 4-Conclusion(s)The present research has been conducted with the aim of zoning the risk of desertification based on groundwater resources in the surrounding area of Lake Urmia in the time period from 2000 to 2018 using Medalus desertification model. According to the obtained results, 212 square kilometers of the total area of the case study are in the very severe desertification class, 338 square kilometers are in the severe desertification class, 1,708 square kilometers are in the moderate desertification class, 4,723 square kilometers are in the poor desertification class, and 7,414 square kilometers are in the no desertification class. The parts located in the south and southeast of the case study area have been affected more than other areas by the destruction of groundwater resources and subsequently the occurrence of desertification phenomenon. Because the four indicators of the water electrical conductivity ratio, the chlorine ratio, the sodium absorption ratio, and the water table drop ratio have the highest ratio. Alluvial aquifers adjacent to the lake have been exploited beyond their allowable capacity limit in recent decades, which along with the drought of the last decade has disturbed the balance of groundwater reserves and also the balance between saline and fresh water in alluvial aquifers. As a result, in some parts of alluvial aquifers near the lake, saline groundwater has infiltrated fresh water and affected its quality. On the other hand, with the increase of irregular abstraction of groundwater, the water level has risen in some areas and has caused desertification by reducing the ratio of soil ventilation.The high ratio of chlorine existing in groundwater is among the factors of soil salinity and a factor that limits the growth of vegetation in the case study area. The ratio of electrical conductivity of groundwater in the case study area is also significant due to reduced rainfall and increased evaporation ratio. This point has led to the destruction of soil structure and the creation of problems in lands drainage and has reduced and decreased the vegetation of the area quantitatively. The investigation of factors affecting the destruction of water resources showed that the geological factor and the presence of geological formations of the third period and quaternary alluvium, and agricultural and garden land use with the highest ratio of table level drop have had an important role in reducing groundwater quality and as a result, the desertification in the case study area.
Davoud Mokhtari; Mohammad Hossein Rezaei Moghaddam; Somayyeh Moazzez
Abstract
1-IntroductionDebris flows are mass movements that always threaten human activities and cause a lot of damage. The aim of this study was to zoning the risk of debris flow in the Leilan Chai catchment located in East Azerbaijan province and the impact of this hazard on the Leylan alluvial fan. For this ...
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1-IntroductionDebris flows are mass movements that always threaten human activities and cause a lot of damage. The aim of this study was to zoning the risk of debris flow in the Leilan Chai catchment located in East Azerbaijan province and the impact of this hazard on the Leylan alluvial fan. For this purpose, 10 effective criteria in the occurrence of this hazard, including slope, aspect, elevation classes, land use, lithology, precipitation, distance to fault, river density, distance to river and distance to road were used to prepare a zoning map for debris flow hazard. Identifying areas with high risk sensitivity helps regional managers and planners to manage and control this risk in the basin.2-MethodologyLeilan Chai catchment as one of the tributaries of Zarrineh Rood River is one of the important rivers in the eastern part of Lake Urmia (Movahed danesh, 1999:45). This basin is located in East Azerbaijan province in terms of political divisions. The area of this basin is 723 Km2 and is located in the geographical coordinates of 37° 00′ 31″ to 37° 38′ 20″ north latitude and 46° 14′ 26″ to 46° 38′ 37″ east longitude. The minimum elevation of the basin is 1356 meters and the maximum elevation in the heights of Sahand Mountain is 3554 meters. This basin forms an alluvial fan at the exit of the mountain that called Leilan. In the present study, the SAW decision-making method has been used to weight the criteria. Layer fuzzy was also performed due to their importance in the occurrence of debris flow in ArcGIS and Idrisi software.3-Results and DiscussionMass movements such as debris flows have always been a threat to the development of human activities. The results of weighting the criteria using SAW method showed that lithology, slope and precipitation criteria with a weight of 0.260, 0.211 and 0.190, respectively, are of more importance in the occurrence of this hazard in the study area. After determining the weight of the criteria and sub-criteria, the layers were overlapped in the GIS environment and a potential map of the risk of debris flow in 5 classes was prepared. The results of the final map show that upstream of the basin area due to having high altitude and receiving more rainfall during the year and also having a high slope are highly sensitive to the occurrence of debris flow. The downstream areas of the basin, despite the high density of river and the presence of numerous faults, but due to the very low slope, show low sensitivity to the occurrence of debris flow.4-ConclusionIn this study, an attempt was made to prepare a map of the risk of debris flow occurrence in the Leilan Chai basin using effective criteria in the occurrence of this risk. The final debris flow hazard map was prepared by overlaying and multiplying the final weight of the criteria in fuzzy layers in GIS environment. The results showed that about 117 Km2 (16% of the area) of the study area is in the high and very high risk classes in terms of sensitivity to debris flow. In contrast, 49% of the total area is low and very low sensitivity to this risk. Areas located in high and very high classes mainly include the upper parts of the basin, which have the potential for this risk in terms of slope, precipitation (more than 400 mm) and lithology (presence of volcanic ash). Also, according to the research results, it can be said that this hazard cannot have much effect on the Leilan alluvial fan. Due to the occurrence of this hazard in the upper parts of the basin, the possibility of transferring these materials to the downstream areas and even the surface of the alluvial fan is very low due to the very long distance.
fatemeh parhizkar; Masume Rajabi; Mojtaba Yamani; Davoud Mokhtari
Abstract
1-Introduction For thousands of years, mangrove forests have played a significant role in the economy and sustainable livelihoods of human societies. Therefore, identifying and measuring changes in the boundaries of mangroves over time can play an important role in planning and conducting effective protection ...
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1-Introduction For thousands of years, mangrove forests have played a significant role in the economy and sustainable livelihoods of human societies. Therefore, identifying and measuring changes in the boundaries of mangroves over time can play an important role in planning and conducting effective protection measures and reducing the vulnerability of mangroves to natural and human hazards. This study aimed to investigate changes in mangrove forests and the relationship between these changes and marine hydrodynamics and coastal morphology in parts of the north and east of the Strait of Hormuz for 47 years. 2-Methodology In this study, Landsat satellite images, MSS, TM, ETM +, OLI sensors from 1972 to 2019 were used to monitoring mangrove forest changes in the west of the Hormuz Strait. In the next step, the necessary preprocesses (radiometric and atmospheric corrections) were applied to the images in ENVI 5.3 software. And the classification of images was done by SVM, MLC, and ANN methods, and considering that to finalize the land use map, all classification accuracy indicators should be adjusted with one or more valid statistical indicators. The kappa index and general accuracy are among the statistical methods used. Post-processing operations also included the integration of classes that were applied to make the land use map more eloquent and eliminate single pixels on different classes. In the next step, the Change Detection method was used to detect changes and tell the results of the classifications. The next step is to convert the classified image to polygon and transfer it to the Arc GIS environment to manage the classes. Of course, the class that is most important to us here is the Mangrove Forest class, which was examined in the period 1972-2019. After the changes in the mangrove forests were identified, with the help of 1: 25000 topographic maps, contours of 2 meters of the range were prepared and the slope map was prepared using DEM images of the area. Also, using the half-hour tide data, the minimum, maximum, and average tide rates of Jask, Shahid Rajaee, Hormoz, and Sirik stations were calculated and finally, these data and maps were prepared to examine the development potential of mangrove forests. 3-Results and Discussion Land use maps were developed using Landsat images using three pixel-based classification algorithms (MLC, SVM, ANN) and the accuracy of the results was assessed using random points. The results showed that the highest overall accuracy and kappa coefficient were 99.44 and 0.99 for region A, and 98.41, 0.97, for region B, for SVM, respectively. Our study showed that SVM could be the most appropriate classification method for this study area. Therefore, SVM land use maps were prepared for the study area for 1972, 1987, 2002, and 2019. After preparing the land-use change map, it was stated that mangrove forests in region A accounted for 55.84% and in region B for 36.18%, tidal areas in region A accounted for 27.63%, and in Area B is 36.58 percent, Water Areas A is 3.04 percent, Area B is 1.78 percent, dry land is 15.37 percent and region B is 99.99. 7% have changed over the past 47 years. To explore the potential for the expansion of mangrove forests, we examined the slope of the region and its relationship with the average tide in the region. Comparing the results of the increasing and decreasing trend of mangrove forests with curves corresponding to the average tidal level and morphological features of the region, we conclude that the study area is about the hydrodynamic characteristics of the sea such as the average tidal area and extent. The catchment area, the height of the waves, and the coastal morphology such as slope and sediments and the water entering the areas from the Hasanlangi River and the Gaz and Hivi rivers have a very high potential for further development of mangrove forests. 4-Conclusion The results show that in the northern part of the Strait of Hormuz, the area of mangrove forests has increased in all the years, but in the eastern part of the study, we have always faced a decreasing and increasing trend and we don't see this part significant development during these 47 years in mangroves. However, according to the study of the geomorphic features of the region such as slope, topography, and the presence of Sabkha and Firth and sediments from the rivers of Hassan Langi, Gaz, and Hivi, as well as the average tide of the region and the vast area it covers, The study has the potential to develop mangrove forests. The results of this study can provide significant information about the progress or regression of mangroves in different coastal areas, can significantly help to implement protection measures and rehabilitate Iranian mangroves.
shahram roostaei; davood mokhtari; christin jananeh
Abstract
1-IntroductionMass movements of the earth's surficial materials downward the slopes is called slope instability, which is affected by the earth gravity, while the rate of material mobility increases by the presence of water in the sediments. Each year, slope instabilities cause enormous economic damages ...
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1-IntroductionMass movements of the earth's surficial materials downward the slopes is called slope instability, which is affected by the earth gravity, while the rate of material mobility increases by the presence of water in the sediments. Each year, slope instabilities cause enormous economic damages to roads, railways, power transmission and communication lines, irrigation and watering canals, ore extraction, as well as oil and gas refining installations, infrastructures in cities, factories and industrial centers, dams, artificial and natural lakes, forests, pastures and natural resources, farms, residential areas and villages or threaten them. Nowadays, many instabilities are resulted by human intervention and manipulations. One of the human factors effective in the instability occurrence is the construction of roads. Road construction, especially in mountainous areas, increases the probability of occurrence of various types of instabilities, as it changes the natural balance of the slopes and causes deformations in the land. Each year, lots of casualties and financial losses are imposed by the occurrence of various types of instabilities in the slopes overlooking the roads, which also cause the destruction of many natural resources in the country. However, the construction of roads, highways and freeways is necessary and unavoidable in today’s life.The Karaj-Chaloos road and the Tehran-North highway are two routes that connect Tehran as Iran’s capital, with the southern shores of the Caspian Sea, although suffering frequent slope instabilities.2-Methodology This contribution aimed to study slope instabilities along these roads using logistic regression method. In this regard, layers of 14 effective factors were identified, comprised of elevation classes, slope, aspect, geology, land use, precipitation, distance from fault, river and road, normalized difference vegetation index (NDVI), climate, slope length (LS), stream power index (SPI) and topographic wetness index (TWI). Consequently, maps of the factors responsible for instabilities were prepared as separate layers in the GIS environment and transferred into the Idrisi software. The whole procedure included: (1) preparation of digital elevation model (DEM), river and fault layers based on the 1:25,000 topographic map of the area, as well as distance maps from rivers and faults, (2) creating slope and aspect maps from DEM, (3) preparation of land use and NDVI maps of the region based on unmatched classification of Landsat 8 image of OLI sensor, (4) preparation of geological map, (5) preparation of precipitation and climate layers based on the information obtained from the meteorological organization, (6) creating LS, SPI and TWI layers based on the DEM, (7) conversion of the distribution data of the regional instabilities using Landsat satellite and Google Earth images, (8) correlating the information layers with the regional instability map and calculating their density per unit area, and (9) performing the logistic regression model using Idrisi software.3-Results and Discussion Results obtained by applying logistic regression model showed that the most important factors affecting slope instabilities in the Karaj-Gachsar road area were the distance from river, climate and SPI, while those for the Tehran-Soleghan road area were the distance from fault and road and climate. 34.95 percent of the lands in the Karaj road area had medium to high potential for instability occurrence; 54.87 percent of the occurred instabilities corresponded to these areas. Moreover, 4.97% of the Karaj road area had a very high potential for instabilities, which correlated with almost 9% of the occurred instabilities. This was while 27.14% of the Soleghan road area possessed medium to high potential for instabilities, within which 86.26% of the instabilities have occurred. Furthermore, 4.57% of the Soleghan road area showed very high risk in terms of instability occurrence, encompassing 61% of the occurred instabilities. According to the prepared maps, the southern and middle parts of the Karaj-Gachsar road, as well as another part in the northwest of the study area had the highest potential for the occurrence of instabilities, whereas in the Tehran-Soleghan road area, the middle and southern parts and a small section in the north of the area had the highest potential for instability occurrence. By comparing these two areas, it was conceived that areas with medium to high potential of instability in the Soleghan road area were less than those of the Karaj road area (27.24% and 34.95%, respectively). However, the percentage of instabilities occurred in the Soleghan road area was much higher (86.26%) than the Karaj road area (54.87%). The high value of the ROC index and its proximity to the end value of 1 in both areas indicated that instabilities strongly correlated with the probability values derived from the logistic regression model. Additionally, the assessment of the instability potential map by the SCAI index showed that there was a high correlation between the prepared risk maps and the occurred instabilities, which have been confirmed by field surveys. The obtained results were in a good agreement with the general opinion that SCAI decreases especially in high and very high risk classes indicating a high correlation between the prepared risk maps and the occurred instabilities and field surveys in both areas.4-ConclusionThe results of this investigation showed that the logistic regression model was suitable for preparing the zonation of the probability of instability occurrence along the edges of the studied roads. Moreover, in addition to natural factors, the human-made factors and particularly unsystematic road construction can play an important role in the instability occurrences on the slopes overlooking the roads. In order to reduce the relative risks and increase the stability of the slopes, it is necessary to avoid manipulating the ecosystem and changing the current land use as much as possible, in addition to policy making for constructions in accordance with geomorphological and geological features of the area.Keywords:Instability, Logistic Regression, Tehran-North highway, Karaj-Chaloos road, Risk zonation.
Volume 1, Issue 1 , January 2015, , Pages 1-19
Abstract
Security of water has been one of the most important issues in the world from the early days to present. Water supplies have always been valuable resources used by people. In the current situation with the rising population, agriculture and industrial developments, high demand for water, uncontrolled ...
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Security of water has been one of the most important issues in the world from the early days to present. Water supplies have always been valuable resources used by people. In the current situation with the rising population, agriculture and industrial developments, high demand for water, uncontrolled and unprincipled exploitation, droughts, and climatic fluctuations, the knowledge of the potential capacity in water supplies in each area is an essential factor in making decision for conservation and optimum utilization of water resources. The purpose of this study was to investigate and identify the effective hydrogeomorphological factors on water supply and replacement of settlements in Miandoab plain. To accomplish this, Satellite images - the image of TM, 2011 - were used. Factors like the slope, lithology, land use, distance to fault, distance from river, rainfall, elevation and vegetation were prepared in GIS environment. Then, the layers were weighted by using Analytic Hierarchy Process (AHP). The results showed that Analytic Hierarchy Process proved more efficient in determining the effective hydro- geomorphological factors on water supply in area under study. It also showed that the interpretation of the coefficients, distance from river, rainfall and altitude, have an important role in this field.
