Geomorphology
leila aghayary; sayyad Asghari Saraskanrood; Batool Zeynali
Abstract
control and monitoring solutions. By using field studies, geological and topographical maps, and by reviewing the researches and studies done in this field, as well as examining the existing conditions in the studied area, 9 factors of elevation, slope, slope direction, lithology, distance from the fault. ...
Read More
control and monitoring solutions. By using field studies, geological and topographical maps, and by reviewing the researches and studies done in this field, as well as examining the existing conditions in the studied area, 9 factors of elevation, slope, slope direction, lithology, distance from the fault. , the distance from the river, the distance from the communication roads, land use and rainfall were investigated as factors affecting the occurrence of landslides. Therefore, the purpose of this research is to investigate and analyze the most important factors involved in creating the risk of landslides in Garami city and to identify the prone areas that will probably be involved in landslides in the near future. In this research, the zoning of prone areas was done with the Aras multi-criteria algorithm in the Edrisi software environment, and according to the results of landslide risk zoning; The criteria of land use, slope, and lithology are the most important factors involved in creating the risk of landslides in the study area with weight coefficients of 0.187, 0.152, 0.152, and 0.142, respectively, and are 361.99 and 450.32, respectively. A square kilometer of the area has a very high probability of danger. Finally, it can be said that the most important factor involved in increasing the amount and potential of landslides in Germi city is the change of land use and the increase of agricultural land and livestock pastures.
Groundwater
sayyad Asghari Saraskanrood; Maryam Riahinia
Abstract
Today, due to population increase, industrial development, excessive exploitation, droughts, exploitation of underground water has multiplied. Therefore, identifying areas with underground water as one of the important sources for providing drinking water, agriculture, and various industries is considered ...
Read More
Today, due to population increase, industrial development, excessive exploitation, droughts, exploitation of underground water has multiplied. Therefore, identifying areas with underground water as one of the important sources for providing drinking water, agriculture, and various industries is considered to be one of the important and necessary issues in water resources management. The purpose of this research is to investigate and zonate the areas with underground water in Khorram Abad plain located in Lorestan province using convolutional neural network method. For this purpose, maps of nine factors affecting underground water were first prepared in the ArcGist environment. In the convolution method, the number of samples was determined as the ratio between the training set and the test set was 70:30, and the convolution neural network framework was used as 2 convolution layers and 2 integration layers, 2 complete connections. layers and finally the sigmoid layer was used for classification from the 3-3 convolution kernel, the Relu function as the activation function and the cross entropy function as the loss function. The obtained maps were classified into 5 classes: very good, good, average, low and very low. Confusion matrix was also used to validate the results of the model. 30% of the real data was used for evaluation, which resulted in an overall accuracy of 92%, that is, the model was able to correctly identify 92% of the data as underground water and 93% as the absence of underground water. The analysis of the groundwater potential map of the convolutional neural network model shows that about 57% of the area is in low groundwater conditions and 43% of the area is in good groundwater conditions.
Geomorphology
leila aghayary; Mousa Abedini
Abstract
Therefore, the purpose of this research is to investigate and analyze the most important factors involved in creating the risk of subsidence in the Ardabil plain and to identify the susceptible surfaces that are likely to be involved in subsidence in the near future. The purpose of this research in the ...
Read More
Therefore, the purpose of this research is to investigate and analyze the most important factors involved in creating the risk of subsidence in the Ardabil plain and to identify the susceptible surfaces that are likely to be involved in subsidence in the near future. The purpose of this research in the first stage is to evaluate the subsidence using radar interferometry technique in the Sarscape software environment, using the capabilities of A1 Sentinel images in the time frame of 2016 and 2021, and also in the following, in relation to the zoning of susceptible areas with the algorithm Aras multi-criteria was implemented in Edrisi software environment. The results of the present study showed that between 0 and 22 mm of subsidence has occurred in the studied area, and the highest amount of subsidence is concentrated in the central part and then in the eastern and north-eastern parts. According to the results of subsidence risk zoning; The criteria of water level drop, distance from the river, geology, and land use are the most important factors involved in creating the risk of subsidence in the study area, respectively, with a weighting factor of 0.221, 0.166, 0.152, and 0.147, respectively, and 267/41 and 403/21 square kilometers of the range have a very high probability of danger. Finally, it can be said that the most important factor involved in increasing the amount and potential of subsidence in the Ardabil plain is the excessive use of underground water and the drop in the water level.
Hydrogeomorphology
Mohammad Hossein Rezaei Moghaddam; Fariba Karami; Kolson Abazari
Abstract
Floods are one of the most destructive natural disasters that cause huge and frequent human losses ,financial and resource losses all over the world(Mishra & Sinha, 2020,1). Flash floods are caused by heavy rains and due to the sudden accumulation and release of runoff from upstream to downstream. ...
Read More
Floods are one of the most destructive natural disasters that cause huge and frequent human losses ,financial and resource losses all over the world(Mishra & Sinha, 2020,1). Flash floods are caused by heavy rains and due to the sudden accumulation and release of runoff from upstream to downstream. This natural phenomenon is the result of the activity of two groups of different parameters. The first group is the meteorological features that change according to space and time. The second group of fixed parameters includes geomorphological and geological characteristics(Youssef et al, 2011,755).Therefore, identification and zoning of areas prone to flood risk is necessary for sustainable development planning and protection of human societies(Farhan & Ayed, 2017, 719). The Ojan Chai basin, which has been flooded in recent years, especially due to human intervention in basin system. One of the most unprecedented floods occurred in this basin in 2016. Therefore, according to the history of flooding in this basin, it is necessary to assess and zoning the risk of sudden flood. The aim of the current research is to evaluate and zoning flash flood-prone areas in the basin based on physiographic characteristics, which is the basis of the modified flash flood potential index (MFFPI).
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 ...
Read More
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.
Hydrogeomorphology
Jafar Jafarzadeh; Meysam Argany
Abstract
Groundwater is one of the most important natural resources in arid and semi-arid regions. The purpose of this study is to identify areas that have groundwater capacity and to prioritize the factors affecting it. In this study, 11 indicators affecting groundwater capacity including Slope, Elevation, Aspect, ...
Read More
Groundwater is one of the most important natural resources in arid and semi-arid regions. The purpose of this study is to identify areas that have groundwater capacity and to prioritize the factors affecting it. In this study, 11 indicators affecting groundwater capacity including Slope, Elevation, Aspect, Distance from River, Drainage Density, Distance from Fault, Topographic Wetness Index, and Topographic Position Index, lithology, Land use and Relative Slope Position were used. 30% of the totals of 230 wells were randomly placed in the validation data group and 70% in the training data. To prioritize the effective factors and zoning of groundwater potential in Ghorichay watershed, the random forest method was used using ArcGIS and to evaluate the model of relative performance curve (ROC) and Area Under the curve surface (AUC). The results showed that the groundwater capacity of about 8% of the watershed is higher at the outlet of the watershed. According to the VIP diagram, the TWI layer with a value of 0.329 and the distance from the river layer with a value of 0.175 was the most and the least influential factors on groundwater capacity, respectively. The area below the AUC curve showed an accuracy of 87% in the training phase to identify areas with groundwater potential. The result of this study can be used in groundwater management in the Ghorichay watershed.
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, ...
Read More
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.
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 ...
Read More
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.
Abbasali Vali; Mahvash Mehrabi
Volume 6, Issue 19 , September 2019, , Pages 125-143
Abstract
Introduction According to some researchers, predeting and preventing water shortages is not possible. However, by fitting the distribution of the probability to the data of a river, it is possible to determine the incident corresponding to the probability of the occurrence or a certain period of return, ...
Read More
Introduction According to some researchers, predeting and preventing water shortages is not possible. However, by fitting the distribution of the probability to the data of a river, it is possible to determine the incident corresponding to the probability of the occurrence or a certain period of return, and with the management and implementation of the drought management programs to reduce its effects and consequences. Hydrological droughts affect vast areas and are detected by reducing lake water storage, lowering groundwater levels, and decreasing river flow flux. This decline in river flow fluctuates from two environmental and management perspectives on water resources. On the other hand, hydrological drought affects the agricultural sector and causes irreparable damages to this sector. Therefore, the importance of studying hydrological droughts is shown in relation to other droughts. Droodzan dam basin is one of the mountainous basins of central plateau of Iran located in the northwest of Fars Province. It provides approximately 760 million cubic meters of water per year, including drinking water, and agricultural and industrial facilities in and around the area. Recently, due to drought, it has faced severe water losses. Therefore, the preservation and maintenance of the reservoir of this dam and the continuity in exploitation of water resources requires attention to its watershed and the potential of water production in the river basin. Therefore, studying the hydrological status of surface waters of the basin can have a special place in the management of drought in the country. Methodology In this study, 5 stations that had appropriate data during a long statistical period were selected. Reconfiguration of the statistical defects was done using the correlation between stations and using the SPSS software. After reconstructing the statistical defects and completing the data, their homogeneity was analyzed using run test and SPSS software. Then, the river flow index was calculated at 3, 6, 9, and 12-month intervals during the statistical period of 28 for each station. In this study, for the frequency analysis, the data from series of limit values were used and fitted with the probabilistic theoretical fit. Chi-Square and Kolmogorov-Smirnov tests were used to determine the appropriate distributions for each time scale using Chi-square fit test. Then, the return period for each of the drought conditions was obtained on the basis of the river flow index at each time period and was extracted from the frequency analysis curve of each station. Results The results of the data homogeneity were studied. The data of all stations were at a level of confidence of at least 99%. In general, the results of the river flow index were very similar at different time scales and indicated the severity of the drought in these years (64-65, 80-78, and 92-87). This increase was observed at 9 and 12-month intervals. Also, the number of years in which mild drought occurred at a time scale of 9 and 12 months, was compared to the 3 and 6-month time scales. In the abundant analysis, the normal distribution of the 3-month river flow index, the distribution of generalized limit values for the river flow index of 9 and 6 months, and the exponential distribution of the 12-month river flow indices were recognized as the best distributions. Discussion and conclusion The results obtained from the calculation of the studied indices showed an increase in the severity of the hydrological drought, especially in the recent decades. River flow index is one of the indicators of the hydrological drought assessment, which can be a good measure for assessing the drought phenomenon in the region. This indicator is also very efficient and has a high sensitivity to other drought indicators. In addition, the zoning maps showed that in the northern and eastern regions of the mild drought, less than the other regions, except for the 6-month period, they were less likely to return to the rest of the period. In the case of the moderate and severe droughts, this was true in the northern parts of the region. In general, with the increase in the return period, the extent and severity of the drought in the area increased. Particularly the northern and eastern areas of the studied watershed were more prone to these natural disasters. Therefore, this area was exposed to economic and social damages and hydrological droughts, so water resources studies require more attention. Thus, the drought risk poses these areas to severe economic, social, environmental, agricultural, and ecological degradation. These areas can serve as short-term and medium-term goals of integrated strategic management and operational plans.
Mehdi Dini; Abrahim Mohammadi Aydinlo
Volume 5, Issue 15 , October 2018, , Pages 17-35
Abstract
Abstract
Introduction
Due to an intense loss in groundwater level and a high decrease in reservoir capacity, the Marand plain has been banned since 1991. However, since 1994, the groundwater level been dropping year by year. As a result, many wells and qanats have been dried or their discharge capacity ...
Read More
Abstract
Introduction
Due to an intense loss in groundwater level and a high decrease in reservoir capacity, the Marand plain has been banned since 1991. However, since 1994, the groundwater level been dropping year by year. As a result, many wells and qanats have been dried or their discharge capacity has been decreased, which has caused a lot of problems for the operating organizations. In this study, to investigate and manage the groundwater level variation in the Marand plain, three scenarios including supplying all consumption from groundwater resources, supplying drinking and industry consumption from the Aras River, and supplying drinking and industry consumption from the Aras River and applying the optimal management of the consumption for agricultural uses were defined. The water balance equation was used to establish the relationship between input, output, storage in an aquifer, and a variation of groundwater level in the Marand plain was estimated based on the available data (2005-2014). Finally, the zoning of the groundwater level was done for the September 1398 and the results were compared with the September 1393.
Methodology
In this research, the Marand plain with an area of 562.22 km2 in the northwest of East Azerbaijan province was selected as a case study. Investigating the hydrological and meteorological parameters of the Marand plain between the years 1982 and 2013 showed that the average annual precipitation was 283 mm, the average annual temperature was 12.8°C, and the average annual pan evaporation was 104 mm. The aim of this research was to estimate the spatial and temporal variation of the groundwater level of the Marand plain. For this purpose, the water balance estimation was done by using Excel and the zoning of groundwater level variation was done by using ArcGIS. A groundwater level analysis of the Marand plain was carried out based on the 50 observations of wells during 2005 to 2014. In this period, according to the groundwater level data, the aquifer parameters, such as the loss of the groundwater level and the amount of water withdrawal from the aquifer were determined. Then, various scenarios were defined for assessing the status of the aquifer.
Result and Discussion
The analysis of the groundwater level in the Marand Plain in a year statistical period (1982-2013) showed that the groundwater level of the plain had decreased about 16.56 m. Also the average annual groundwater level of the plain decreased about 48 cm between the years 2005 and 2015.
By applying the first scenario, in the next five years, the fall of the groundwater level in the zone 1 will be 2.35 m, in the zone 2 will be 2.25m, in the zone 3 will be 2.6m, and in the zone 4 will be 2.45m.
Also the area of the zone 4 had increased from 246 km2 to 252 km2 which indicated a further fall of the groundwater level in a large area of the plain. By applying the second scenario, in the next five years, the growth of the groundwater level in the zone 1 will be 1.74 m, in the zone 2 will be 1.67 m, in the zone 3 will be 1.93 m, and in the zone 4 will be 1.82 m. Indeed, following this trend, the groundwater level after 14 years will return to the situation of 10 years ago (2005). In addition, after 46 years, it will return to the situation of 32 years ago (1982). By applying the third scenario, in the next five years, the growth of the groundwater level in the zone 1 will be 4.78 m, in the zone 2 will be 4.58 m, in the zone 3 will be 5.29 m, and in the zone 4 will be 4.99 m. Following this trend, the groundwater level after 5 years will return to the situation of 10 years ago (2005). After 17 years, it will return to the situation of 32 years ago (1982).
Conclusion
The aim of this research was to estimate the spatial and temporal variation of the groundwater level in the Marand plain. The results showed that the annual average groundwater level had decreased 48 cm/year between the years 2005 and 2014. Also by applying the first scenario, with an intensified decline in the groundwater level in all zones, the status of the Marand aquifer becomes more critical. For example, in some areas, the groundwater level will decease about 2.6 m. By applying the second scenario, the groundwater level will increase at least 1.67 m and utmost 1.93m and by following this trend, after 14 years, the aquifer will return to the situation of 2005. Also by applying the third scenario, the groundwater level will increase at least 4.78 m and utmost 5.29m and by following this trend, after 5 years, the aquifer will return to the situation of 2005.
Zeynab Alimirzaei; Rafat Zare Bidaki; Rasool Zamani-Ahmadmahmoodi
Volume 5, Issue 15 , October 2018, , Pages 115-133
Abstract
Abstract
Introduction
Drought is a natural phenomenon that may occur in all areas of land under any climate conditions. Scientific study of drought is essential for water resource planning and management and for mitigating water shortages. Low rainfall is the main cause of the occurrence of drought. ...
Read More
Abstract
Introduction
Drought is a natural phenomenon that may occur in all areas of land under any climate conditions. Scientific study of drought is essential for water resource planning and management and for mitigating water shortages. Low rainfall is the main cause of the occurrence of drought. Precipitation reduction in a period of time than long term average of an area is defined as meteorological drought. Hydrological drought is defined as a significant reduction in available water of all forms in a landscape. Meteorological droughts lead to hydrological droughts with decreasing flow rates and aquifer discharge.
Methodology
In order to quantify drought phenomenon, some indicators on the basis of drought definitions or computational methods were provided. These indicators are calculated for a single point, but the extent of the drought and its severity vary in different parts of the basin and it is the key point of water resource management and planning for mitigation of drought crisis. The purpose of this study was to investigate the spatial and temporal variations of climatic and hydrologic drought in the North Karun Basin. In this study, some of the meteorological and hydrological indicators such as Deciles (DI), Z score, Standardized Runoff Index(SRI), Stream flow Drought (SDI), Standardized Water Index (SWI) and Groundwater Resource Index (GRI) were calculated to assess the status of the study area. In order to expand point information and convert it to spatial information, after calculating different indices, the meteorological and hydrological drought severity mapping was done using Kriging and IDW(with power 1, 2, 3 and 4) methods.
Result and Discussion
The results of the meteorological drought indices showed that during the 30-year period (1974-2014), the studied area had experienced a severe drought only once between the years 2007 and 2008. The SDI index showed that the river flows had declined at the same time as the meteorological drought between the years 2007 and 2008. In addition, the river flow drought (2007-2008) is clearly obvious in the next water year. In recent years, the SDI has fluctuated from moderate to severe drought, and in general, all stations experienced a moderate drought. SWI indicator analysis showed that groundwater level drop in the North Karun Basin occurred in 2007 and 2008, that has been delayed by one year to the meteorological drought. The results of the GRI in the North Karun Basin showed that the hydrological drought began between 2007 and 2008. Due to the sharp drop in groundwater level, the severity of the groundwater drought in recent years has been dramatically increased in the plains of the study area. The analysis of the Z index map indicated that while the drought is more intense in the eastern parts of the basin, it is less severe and intense in its northern and southern parts. Groundwater drought zoning showed that the severity of groundwater drought in the northeast and southeast of the plains is high. The Shahrekord plain is one of the most important plains in the North Karun Basin, because it has the main concentration of agricultural and animal husbandry activities and has undergone a sharp decline in groundwater over recent years. The groundwater level of this plain reached its lowest level between the years 2013 and 2014.
Conclusion
In general, the findings indicated that sever meteorological droughts in the time period of thirty years (1986-2015) occurred in two years (2000-2001 and 2007-2008). But its impact on surface flow and groundwater recharge is significant due to anomalies in the rainfall – runoff process and excessive withdrawals from the groundwater resources. The meteorological and surface water droughts periods in this basin often take one to two years. The duration and severity of droughts, especially in groundwater resources, have been significant in recent years. The results also showed that geostatistical method of kriging with exponential and gaussian model has a high ability for drought zoning. Also, it can be understood that the eastern part of the area has received fewer precipitation than the other parts. This result is also derived from the zoning of groundwater droughts that the eastern parts of the plains are more severely affected by drought. In general, hydrological droughts in the north Karun Basin are more intensive in the southern and southeastern regions. Simultaneous use of the meteorological and hydrological indicators can be a useful tool for the separation of the meteorological and hydrological droughts as well as the assessment of drought in the region.
Abolghasem Amir Ahmadi; Mahnaz Naemi Tabar; Bahar Gholkar ostadi
Volume 4, Issue 11 , September 2017, , Pages 105-125
Abstract
Absract:
Introduction
Landslide is one of the natural phenomena causing many financial losses and casualties in Iran every year (Kamranzadeh, 2014: 101). This phenomenon occurs when the force of materials’ weight is higher than the shear strength of the soil shear force (Memarian et al. 2006: ...
Read More
Absract:
Introduction
Landslide is one of the natural phenomena causing many financial losses and casualties in Iran every year (Kamranzadeh, 2014: 101). This phenomenon occurs when the force of materials’ weight is higher than the shear strength of the soil shear force (Memarian et al. 2006: 105). The Shannon entropy is a function of probability distribution and standard for measuring uncertainty in the information content of a parameter, and by considering occurrence frequency of subgroups of that parameter, it shows heterogeneity level. As a result, it calculates the effect of each parameter on the results of the system (Hosseinpour Mil Arghadan et al. 2014). Objectives of the present study are the selection of criteria and standards, preparation of digital factors layers, preparation of the landslide hazard zonation map, diagnosis of high risk points via the Shannon entropy, presentation of strategies appropriate for preventing possible risks and solutions to reduce damages in the study area. Bajgiran is the central district of Bajgiran County and a part Doulatkhaneh Rural District of Ghouchan Township. According to climate divisions, Bajgiran has a moderate mountainous climate. Geologically and structurally, it is a part of Kopeh Dagh Sedimentary Basin. In terms of stratigraphy, outcrops from the Jurassic rock units to the present era can be observed in the study area.
Materials and methods
In the present study, first of all factors affecting the occurrence of landslide including height, precipitation, slope, slope direction, slope shape, distance from the waterway, distance from the road, distance from the fault, land cover and lithology were identified as factors affecting the occurrence of landslides, and the mentioned maps were digitized in GIS. to this end, using the topographic map on a scale of 1:50000, the Digital Elevation Model Map (DEM), factors of slope degree, slope direction, slope shape, height level, distance from the waterway, and distance from the road were prepared. Using the land-use map on a scale of 1:25000, information layers of land use were extracted. To draw the lithological map, the distance from the fault of the geological map on a scale of 1:50000 was used. To draw the precipitation map, statistics of the rain gauge stations of five Daroungar, Mohammad Taghi Beig, Aman Gholi, Kikan, Hey Hey Ghouchan, and Bahman Jan Stations were used. The information content available in the decision matrix in entropy process is calculated via equation 1:
Equation 1: Ej = -K
Where Ej is the entropy value and Pi,j is the decision matrix.
Equation 2: Pij =
Where rij is the value or the special score assigned to each layer.
Equation 3: K= (lnm)-1
Where k is the fixed coefficient and m is the number of landslides.
After the formation of the decision matrix and extraction of the value of Ej, the value of Vj can be calculated via equation 4:
Equation 4: Vj = 1- Ej
Where Vj is the deviation degree of uncertainty.
And finally, to calculate the final weight of all factors (Wj), equation 5 is employed.
Equation 5: Wj =
To prepare the final map, equation 6 is used:
Equation 6:
Where Hi is the landslide hazard occurrence coefficient, Wj is the final weight of all factors, rij is the weight of each factors (Moghimi et al. 2012: 82).
Results and discussion
After converting criteria into integers and the formation of the initial matrix, the value of Pij was calculated via equation 1 and the value of K was calculated via equation 2. To calculate Ej for each criterion, equation 2 was used. The results are indicated table 2. In this equation, the value of E which is a function of n, for each n where Pi is equal, the value of E becomes maximum which is statistically calculated via probability distribution of Pi. Then, uncertainty or degree of deviation of each criterion (dj) obtained from the fraction of the value of Ej from 1 were calculated per each indices effective on landslides of the study area (table 2). After that, using equation 5, the weight of each parameters used in the entropy matrix of landslides (Wj) including height (0.02113), precipitation (0.031142), shape of slope (0.0116110), slope (0.011342), distance from the waterway (0.045161), distance from the road (0.113401), distance from the fault (0.099871), land use (0.997110), and lithology (0.095148) were obtained. Therefore, the regional model of the landslide hazard degree in the area was obtained via equation 6. Hi is the landslide hazard degree in the area (equation 7).
Conclusion
The aim of the present study was to prioritize factors affecting the occurrence landslides and zone their sensitivity in Bajgiran Region via the Shannon entropy. The results of the study shows that the most important factors affecting landslides in the study area are slope layers, slope direction, lithology, distance from the fault, and height. After weighting parameters and formatting the entropy matrix, the zonation mapping were conducted. To this end, information layers were prepared in Arc GIS and converted into Raster formats. With regard to zoning maps obtained from the entropy model, 15 landslides have occurred in the area among which 9 landslides have occurred in a high risk zone (42%), 4 landslides in a moderate risk zone (31%), and 2 landslides in a low risk zone (27%). Regarding the factor of slope, it can be said that the most landslides have occurred in slopes with 60%. It may because the lack of the soil-formation process prone to slippery movements. In case of the factor of slope direction, the most landslides have occurred in northern domains and in heights with 1600 m high. This results is compatible with the faults and calcareous, marl, and Pyura Chilensis organizations of the area. The results of the present study also show that the entropy model has appropriate performance in identifying risk areas and their zonation. In addition, the results can be used in decision making and management of land use and urban planning.
Majid Ramezani Sarbandi; Reza Ghazavi; Siamak Dokhani; Seyyed Mostafa Mortazavi
Volume 4, Issue 10 , June 2017, , Pages 65-80
Abstract
Groundwater is one of the most important natural resources in the world. Currently, the considerable part of Iran's water consumption, minly its drinking water, is provided from underground water sources. The emission of the surface contaminants to groundwater resources, especially in the arid and semi-arid ...
Read More
Groundwater is one of the most important natural resources in the world. Currently, the considerable part of Iran's water consumption, minly its drinking water, is provided from underground water sources. The emission of the surface contaminants to groundwater resources, especially in the arid and semi-arid regions with a limited water resources is a serious problem. In this research, the DRASTIC and GODS methods were used to study Rafsanjan plain's potential vulnerability to pollution. To this end, seven layers including groundwater depth, net recharge, aquifer media, soil, topography, and unsaturated zone hydraulic conductivity were produced for the DRASTIC method. In addition, to create potential vulnerability maps using GIS for the GODS method, four layers including type of groundwater, unsaturated zone, water table depth, and soil environment were combined. The degree of the changes of the electrical conductivity of the plains was used for the validation of the models. According to the results, the DRASTIC index is between 61.33 and 183.75 for the region, categorizing Rafsanjan plain to five classes of vulnerabilities including very low 0/54%, low 32/93%, medium 55/40%, high10/54%, and very high 0/59%. The GODS model, in contrast, classifies the region to three classes of vulnerability including low 32/27%, medium 67/04%, and high 0/69%. In both models, the most part of the study area was classified into medium level of vulnerability which were respectively 55.40 and 67.04 in the DRASTIC and the GODS models.
Siavash Shayan; Mojtaba Yamani; Manizheh Yadegari
Volume 3, Issue 9 , March 2017, , Pages 139-158
Abstract
Geomorphological features are the basis of natural resources evaluation in the watersheds. These features are affected by many factors such as climate and soil, hydrology, ecology, geology etc. Drainage network in this area was different according to the amount and performance of processes and has different ...
Read More
Geomorphological features are the basis of natural resources evaluation in the watersheds. These features are affected by many factors such as climate and soil, hydrology, ecology, geology etc. Drainage network in this area was different according to the amount and performance of processes and has different effects on their surroundings. Sinkholes are located on the way of this drainage network. In association with the occurrence, the researchers have counting on this subject that the change of soil parameters, indiscriminate harvesting from groundwater, drilling of illegal wells and activity of Shahid-Mofateh thermal power plant are the most important factors for the appearance of these profound sinkholes in the plains of this state. The aim of this study is examining the characteristics of the drainage networks in this region, and study their role in the creating of subsidence in this region. For this purpose all information on geology, hydrology, hydrogeological and geographical data in this area were collected and analyzed. Drainage networks, lithology, slope and elevation of this region were drawn by using of digital topographic maps of 1:50000, geological of 1:100000, DEM and also pictures of Google Earth. Then to evaluate annual changes of runoff we used experimental method of Justin and Katain. The results indicate that the dissimilar changes in morphometric data of drainage network in this area due to the climatic and geological conditions, were most important factors in the intensification of decrease of soil humidity, subterranean water and occurrence of subsidence in this region. Human factors and the over use of water sources were effective in the intensification of subsidence.
Mousa Abedini; Rogayeh Fathi Jokadan
Volume 3, Issue 7 , October 2016, , Pages 1-17
Abstract
Mousa Abedini[1]* Rogayeh Fathi Jokadan[2] Abstract Today flood phenomena is one of the most complex hazardous events, every year more than other natural disaster that caused causality, financial damage and destroyed the agricultural land. Therefore, this research at first has studied the effective ...
Read More
Mousa Abedini[1]* Rogayeh Fathi Jokadan[2] Abstract Today flood phenomena is one of the most complex hazardous events, every year more than other natural disaster that caused causality, financial damage and destroyed the agricultural land. Therefore, this research at first has studied the effective variables in the occurrence of the flood, such as (slope, geology, land and ranking the run off streams). Next, these variables have been entered in to GIS software, then based on their level of importance have been given some weights. Finally, by merging the layers and analyzing them the floodwater risk zonation map created with four zones of risk including: 1- high probability risk zone, 2- relative high probability zone, 3- moderate probability zone and 4- low probability zone. The investigation of natural conditions shows that there are many natural variables for floodwater event. According to the zoning map of floodwater, the high probability risk zone is about 18.86 percent (113.53 square km), the relative high probability zone is about 35.68 percent (215.9 square km), the moderate probability zone is about 29.66 percent (179.29 square km) and the low probability zone is about 15.8 percent (94.58 square km). The findings of the present study show that due to the having average annual of precipitation 1058.7, high slope, and relatively impermeable formations in addition having circle form have relatively high potential in flooding. Keywords: Hydro geomorphology, floodwater, Karganruod basin, Zoning, Arc GIS. [1]- Associate Professor of Geomorphology, University of Mohaghegh Ardabilm, (Corresponding Autor), Email:abedini@uma.ac.ir. [2]- Master's Graduates in Geomorphology, University of Mohaghegh Ardabil.
Volume 2, Issue 2 , January 2015, , Pages 1-24
Abstract
Among all natural disasters floods inflict the greatest damages to agriculture, fisheries, housing and infrastructure seriously affecting the social and economic activities of many people around the world. The many floods which have struck the city of Maku, especially northern mountainous sub ...
Read More
Among all natural disasters floods inflict the greatest damages to agriculture, fisheries, housing and infrastructure seriously affecting the social and economic activities of many people around the world. The many floods which have struck the city of Maku, especially northern mountainous sub basins, leaving behind financial losses and damages to human lives indicates a necessity of an integrate study about flooding in the upstream basins of the region. In this study, first, physiographic characteristics of the study area were determined by using satellite imagery, GIS and WMS analytic functions. Then, the flood zone area was identified, with emphasis on the city of Maku, and finally, the stream flooding was analyzed in the city skeleton. The results showed that rough topography, low thickness of the separate elements on bed rock and their low capacity for water storage, poor vegetation, violating the flood boundaries and changing them to artificial land, provides the conditions for the devastating floods especially during the showery precipitation in the dry seasons. As the findings show the runoff from a rainfall with the 120 mm/h intensity was estimated about 2.5 million m3, that 338000 m3 of it was obtained from the small watershed areas overlooking the city.
