The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2021
Although dams are very useful engineering structures, they can have extremely harmful consequence... more Although dams are very useful engineering structures, they can have extremely harmful consequences if they fail. One example of these failures occurred in Sardoba Reservoir (Uzbekistan). On May 1, 2020, a part of an earthfill dam failed along the Sardoba Reservoir, and a large region with settlements and agricultural areas in Uzbekistan and Kazakhstan was flooded. Accurate mapping and monitoring of the flooded areas are crucial for the damage assessment and the mitigation efforts. Satellite Earth Observation datasets can serve for these purposes due to their greater availability with high spatial and temporal resolutions. However, the optical sensors have limitations for data acquisition due to the atmospheric conditions, particularly the cloud cover, which often severely affects the image usability when floods occur. The synthetic aperture radar sensors provide valuable information under all weather conditions, but their interpretation is relatively difficult. Therefore, a data fusion methodology is proposed here for the integrated use of Sentinel-1 and Sentinel-2 datasets using a set of features obtained from both. Four different feature combinations were evaluated using the random forest classifier. The pre-processing steps for the feature extraction are explained in detail and the results are discussed here. The proposed algorithm exhibits very high classification accuracy for the flooded areas and flooded vegetation classes. The method can be employed for the flash flood mapping at regional scale. In addition, the damage assessment especially for agricultural areas in the region is very important for accounting the economic losses and the resilience purposes.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2018
Susceptibility mapping for disasters is very important and provides the necessary means for effic... more Susceptibility mapping for disasters is very important and provides the necessary means for efficient urban planning, such as site selection and the determination of the regulations, risk assessment and the planning of the post-disaster stage, such as emergency plans and activities. The main purpose of the present study is to introduce the preliminary results of an expert based flood susceptibility mapping approach applied in urban areas in case of Ankara, Turkey. The proposed approach is based on Modified Analytic Hierarchy Process (M-AHP), which is an expert-based algorithm and provides data based modeling. The existing spatial datasets are evaluated in the decision process and the specified number of decision points according to the degree desired can be formed. The parameter priorities can be identified at the beginning of the modeling with this approach by the responsible expert. The spatial datasets used in the modeling and mapping process have been provided by the General Directorate of Mapping (HGM). Additionally, the slope gradient of topography, drainage density, and topographic wetness index of the site being one of the second derivatives of topography have been evaluated to identify the main conditioning factors controlling water accumulation on ground. Considering the uncertainties in flood hazard assessment and limitations in sophisticated analytic solutions, the proposed methodology could be evaluated to be an efficient tool to detect the most influential parameters representing the flood vulnerability and assessing the mitigation applications in urban environment.
The aim of the present study is to prepare a landslide susceptibility map of a region of about 12... more The aim of the present study is to prepare a landslide susceptibility map of a region of about 120 km2, between Gökcesu and Pazarköy (around Mengen, NW Turkey) at approximately 10 km north of the North Anatolian Fault Zone, where frequent landslides occur. For this purpose, mechanisms of the landslides were studied by two-dimensional stability analyses together with field observations,
Owing to the increase in population, transportation has become one of the major research topics. ... more Owing to the increase in population, transportation has become one of the major research topics. Among existing transportation systems, railway is one of the most economic and fast systems, and therefore, there has been an increase in new railway constructions in recent years. In Turkey, the longest railway tunnels, the Bahce-Nurdag high-speed rail tunnels, are under construction in the southern part of the country. This twin tubes tunnels are approximately 10 km in length, and they are excavated using tunnel boring machines (TBM). The tunnel route locates in the East Anatolian Fault Zone and the portal region is composed of debris and old landslide deposits. For this reason, mitigating the potential landslide hazard is critical for the tunnel. Therefore, the present study investigates the TBM tunnelling-landslide relationship by employing 3D numerical analyses. The analyses show that the last 600 m of the tunnel has a potential landslide hazard and some additional measures should be considered along this part to ensure tunnel safety. The tunnel conditions are highly complex, and thus it is an interesting case for tunnel engineers.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
Geospatial data are fundamental to understand the relationship between the geographical events an... more Geospatial data are fundamental to understand the relationship between the geographical events and the Earth dynamics. Although the geospatial technologies aid geodata collection, the increasing possibilities yield new application areas and cause even a greater demand. Considering the increment in data quantity and diversity, to be able to work with the data, they must be collected, stored, analysed and presented with the help of specifically designed platforms. Geographical Information Systems (GIS) with mobile and web support are the most suitable platforms for these purposes. On the other hand, the location-enabled mobile, web and geospatial technologies empowered the rise of the citizen science (CitSci) projects. With the CitSci, mobile GIS platforms enable the data to be collected from almost any location. As the size of the collected data increases, considering automatic control of the data quality has become a necessity. Integrating artificial intelligence (AI) with the CitSci based GIS designs allows automatic quality control of the data and helps eliminating data validation problem in CitSci. For this reason, the purpose of the present study is to develop a CitSci and AI supported GIS platform for landslide data collection because landslide hazard mitigation efforts require landslide susceptibility, hazard and risk assessments. Especially, landslide hazard assessments are necessary the tim e of occurrence of a landslide. Although this information is crucial, it is almost impossible to collect ti me of occurrence in regional hazard assessment efforts. Consequently, use of CitSci for this purpose may provide valuable information for landslide hazard assessments.
Several scientific processes benefit from Citizen Science (CitSci) and VGI (Volunteered Geographi... more Several scientific processes benefit from Citizen Science (CitSci) and VGI (Volunteered Geographical Information) with the help of mobile and geospatial technologies. Studies on landslides can also take advantage of these approaches to a great extent. However, the quality of the collected data by both approaches is often questionable, and automated procedures to check the quality are needed for this purpose. In the present study, a convolutional neural network (CNN) architecture is proposed to validate landslide photos collected by citizens or nonexperts and integrated into a mobile- and web-based GIS environment designed specifically for a landslide CitSci project. The VGG16 has been used as the base model since it allows finetuning, and high performance could be achieved by selecting the best hyper-parameters. Although the training dataset was small, the proposed CNN architecture was found to be effective as it could identify the landslide photos with 94% precision. The accuracy o...
The effective mitigation of risk sourced from mass movements requires systematic approaches. In l... more The effective mitigation of risk sourced from mass movements requires systematic approaches. In large mapping scale or single mass movement case risk assessment can be performed based on conventional geotechnical risk assessment methods, either quantitatively or qualitatively However, in medium to large scale mass movement risk assessment, risk zoning is required which is still very difficult. The main reasons are; lack of systematic methods for mapping of hazard, which involves spatial and temporal evaluation of mass movement probability and lack of mapping methods for potential consequences or worth of losses. In this study, a risk assessment method for qualitative zoning of risk is proposed for the debris flow risk in a selected area from the Western Taurid region of Turkey, because the study area is under debris flow threat. The hazard map is prepared by subjective probability assignments of potential debris flow zones in the study region. The potential debris flow zones are obtained by processing aerial photos and field survey data in geographic information system (GIS) framework. Then a thematic hazard map is prepared in GIS with hazard levels of low, medium and high. The second component of risk, which is consequence or worth of loss mapping, is performed by initially identifying the elements at risk in the study region. The region covers two medium scale towns (Uluborlu and Senirkent) and three villages (Yassioren, Ortayazi and Garip), a forested area under protection, which contains endangered trees of Southwestern Turkey, a main road connecting town and villages to the main city of Isparta and an irrigation channel constructed by The State Hydrolic Works (DSI). The boundaries of residential area are obtained by using Google Earth Technology, and RGB true color composite of Landsat ETM
The success rate in landslide susceptibility mapping efforts increased with the advancements in m... more The success rate in landslide susceptibility mapping efforts increased with the advancements in machine learning algorithms and the availability of geospatial data with high spatial and temporal resolutions. Existing data-driven susceptibility mapping models are not globally applicable due to the high variability of landslide conditioning parameters and the limitations in the availability of up-to-date and accurate data. Among numerous applications, landslide susceptibility maps are essential for site selection and health monitoring of engineering structures, such as dams, for increasing their lifetime and to prevent from disastrous events caused by the damages. In this study, landslide susceptibility mapping performance of XGBoost algorithm was evaluated in a landslide-prone area in the upper basin of Ataturk Dam, which is a prime investment located in the southeast of Turkey. The study area has a size of 2718.7 km2 with an elevation difference of ca. 2000 m and contains 27 litholo...
In railway and highway projects, the expansive soils in arid and semi-arid regions are frequently... more In railway and highway projects, the expansive soils in arid and semi-arid regions are frequently encountered. Expansive clays result in serious damages on light structures. However, direct determination of swelling pressure requires time consuming test procedure and sophisticated laboratory equipment. For this reason, some prediction models for swelling properties of expansive soils have always been attractive, but these models are generally statistical based. Therefore, in this study, a simple and feasible method based on linguistic "if-then" rules is developed and proposed for the rapid determination of swelling pressure depending on Atterberg limits and clay content of soils.
In railway and highway projects, the expansive soils in arid and semi-arid regions are frequently... more In railway and highway projects, the expansive soils in arid and semi-arid regions are frequently encountered. Expansive clays result in serious damages on light structures. However, direct determination of swelling pressure requires time consuming test procedure and sophisticated laboratory equipment. For this reason, some prediction models for swelling properties of expansive soils have always been attractive, but these models are generally statistical based. Therefore, in this study, a simple and feasible method based on linguistic "if-then" rules is developed and proposed for the rapid determination of swelling pressure depending on Atterberg limits and clay content of soils.
This paper describes a study into the relationship between volumetric block proportions and uncon... more This paper describes a study into the relationship between volumetric block proportions and unconfined compressive strength (UCS) of Ankara Agglomerate, a volcaniclastic block and tuff matrix mixture containing relatively weak tuff matrix surrounding stronger pink andesite blocks and very strong black andesite blocks. Volumetric block proportions were estimated using image analysis methods. The pink and black andesite blocks in the bimrock exhibited significant color contrasts with the tuff matrix, which facilitated image analysis of grayscale and RGB colored photographs of outcrops. Estimates of block proportions from image analysis were checked against estimates generated using the zero-dimensional "node-counting method". 2D block proportions estimated from measurements of photographs were considered to be equivalent to the volumetric block proportions because the volcanic blocks were approximately equi-dimensional. The measured volumetric block proportions were incorporated into a further stage of the study by developing regression-based equations to estimate the overall uniaxial compressive strength of Ankara Agglomerate as a function of volumetric block proportions. The non-linear relationship between volumetric block proportions and overall UCS of Ankara Agglomerate, suggests a dependence between overall UCS of the bimrock and the strengths of the different types of blocks. This dependence may be due to variations in block/matrix strength contrasts and requires further study. USA 10065 S.W.
Nowadays several scientific disciplines utilize Citizen Science (CitSci) as a research approach. ... more Nowadays several scientific disciplines utilize Citizen Science (CitSci) as a research approach. Natural hazard research and disaster management also benefit from CitSci since people can provide geodata and the relevant attributes using their mobile devices easily and rapidly during or after an event. An earthquake, depending on its intensity, is among the highly destructive natural hazards. Coordination efforts after a severe earthquake event are vital to minimize its harmful effects and timely in-situ data are crucial for this purpose. The aim of this study is to perform a CitSci pilot study to demonstrate the usability of data obtained by volunteers (citizens) for creating earthquake iso-intensity maps in a short time. The data were collected after a 5.8 Mw Istanbul earthquake which occurred on 26 September 2019. Through the mobile app “I felt the quake”, citizen observations regarding the earthquake intensity were collected from various locations. The intensity values in the app...
Urban areas may be affected by multiple hazards, and integrated hazard susceptibility maps are ne... more Urban areas may be affected by multiple hazards, and integrated hazard susceptibility maps are needed for suitable site selection and planning. Furthermore, geological–geotechnical parameters, construction costs, and the spatial distribution of existing infrastructure should be taken into account for this purpose. Up-to-date land-use and land-cover (LULC) maps, as well as natural hazard susceptibility maps, can be frequently obtained from high-resolution satellite sensors. In this study, an integrated hazard susceptibility assessment was performed for a developing urban settlement (Mamak District of Ankara City, Turkey) considering landslide and flood potential. The flood susceptibility map of Ankara City was produced in a previous study using modified analytical hierarchical process (M-AHP) approach. The landslide susceptibility map was produced using the logistic regression technique in this study. Sentinel-2 images were employed for generating LULC data with the random forest cla...
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2021
Although dams are very useful engineering structures, they can have extremely harmful consequence... more Although dams are very useful engineering structures, they can have extremely harmful consequences if they fail. One example of these failures occurred in Sardoba Reservoir (Uzbekistan). On May 1, 2020, a part of an earthfill dam failed along the Sardoba Reservoir, and a large region with settlements and agricultural areas in Uzbekistan and Kazakhstan was flooded. Accurate mapping and monitoring of the flooded areas are crucial for the damage assessment and the mitigation efforts. Satellite Earth Observation datasets can serve for these purposes due to their greater availability with high spatial and temporal resolutions. However, the optical sensors have limitations for data acquisition due to the atmospheric conditions, particularly the cloud cover, which often severely affects the image usability when floods occur. The synthetic aperture radar sensors provide valuable information under all weather conditions, but their interpretation is relatively difficult. Therefore, a data fusion methodology is proposed here for the integrated use of Sentinel-1 and Sentinel-2 datasets using a set of features obtained from both. Four different feature combinations were evaluated using the random forest classifier. The pre-processing steps for the feature extraction are explained in detail and the results are discussed here. The proposed algorithm exhibits very high classification accuracy for the flooded areas and flooded vegetation classes. The method can be employed for the flash flood mapping at regional scale. In addition, the damage assessment especially for agricultural areas in the region is very important for accounting the economic losses and the resilience purposes.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2018
Susceptibility mapping for disasters is very important and provides the necessary means for effic... more Susceptibility mapping for disasters is very important and provides the necessary means for efficient urban planning, such as site selection and the determination of the regulations, risk assessment and the planning of the post-disaster stage, such as emergency plans and activities. The main purpose of the present study is to introduce the preliminary results of an expert based flood susceptibility mapping approach applied in urban areas in case of Ankara, Turkey. The proposed approach is based on Modified Analytic Hierarchy Process (M-AHP), which is an expert-based algorithm and provides data based modeling. The existing spatial datasets are evaluated in the decision process and the specified number of decision points according to the degree desired can be formed. The parameter priorities can be identified at the beginning of the modeling with this approach by the responsible expert. The spatial datasets used in the modeling and mapping process have been provided by the General Directorate of Mapping (HGM). Additionally, the slope gradient of topography, drainage density, and topographic wetness index of the site being one of the second derivatives of topography have been evaluated to identify the main conditioning factors controlling water accumulation on ground. Considering the uncertainties in flood hazard assessment and limitations in sophisticated analytic solutions, the proposed methodology could be evaluated to be an efficient tool to detect the most influential parameters representing the flood vulnerability and assessing the mitigation applications in urban environment.
The aim of the present study is to prepare a landslide susceptibility map of a region of about 12... more The aim of the present study is to prepare a landslide susceptibility map of a region of about 120 km2, between Gökcesu and Pazarköy (around Mengen, NW Turkey) at approximately 10 km north of the North Anatolian Fault Zone, where frequent landslides occur. For this purpose, mechanisms of the landslides were studied by two-dimensional stability analyses together with field observations,
Owing to the increase in population, transportation has become one of the major research topics. ... more Owing to the increase in population, transportation has become one of the major research topics. Among existing transportation systems, railway is one of the most economic and fast systems, and therefore, there has been an increase in new railway constructions in recent years. In Turkey, the longest railway tunnels, the Bahce-Nurdag high-speed rail tunnels, are under construction in the southern part of the country. This twin tubes tunnels are approximately 10 km in length, and they are excavated using tunnel boring machines (TBM). The tunnel route locates in the East Anatolian Fault Zone and the portal region is composed of debris and old landslide deposits. For this reason, mitigating the potential landslide hazard is critical for the tunnel. Therefore, the present study investigates the TBM tunnelling-landslide relationship by employing 3D numerical analyses. The analyses show that the last 600 m of the tunnel has a potential landslide hazard and some additional measures should be considered along this part to ensure tunnel safety. The tunnel conditions are highly complex, and thus it is an interesting case for tunnel engineers.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
Geospatial data are fundamental to understand the relationship between the geographical events an... more Geospatial data are fundamental to understand the relationship between the geographical events and the Earth dynamics. Although the geospatial technologies aid geodata collection, the increasing possibilities yield new application areas and cause even a greater demand. Considering the increment in data quantity and diversity, to be able to work with the data, they must be collected, stored, analysed and presented with the help of specifically designed platforms. Geographical Information Systems (GIS) with mobile and web support are the most suitable platforms for these purposes. On the other hand, the location-enabled mobile, web and geospatial technologies empowered the rise of the citizen science (CitSci) projects. With the CitSci, mobile GIS platforms enable the data to be collected from almost any location. As the size of the collected data increases, considering automatic control of the data quality has become a necessity. Integrating artificial intelligence (AI) with the CitSci based GIS designs allows automatic quality control of the data and helps eliminating data validation problem in CitSci. For this reason, the purpose of the present study is to develop a CitSci and AI supported GIS platform for landslide data collection because landslide hazard mitigation efforts require landslide susceptibility, hazard and risk assessments. Especially, landslide hazard assessments are necessary the tim e of occurrence of a landslide. Although this information is crucial, it is almost impossible to collect ti me of occurrence in regional hazard assessment efforts. Consequently, use of CitSci for this purpose may provide valuable information for landslide hazard assessments.
Several scientific processes benefit from Citizen Science (CitSci) and VGI (Volunteered Geographi... more Several scientific processes benefit from Citizen Science (CitSci) and VGI (Volunteered Geographical Information) with the help of mobile and geospatial technologies. Studies on landslides can also take advantage of these approaches to a great extent. However, the quality of the collected data by both approaches is often questionable, and automated procedures to check the quality are needed for this purpose. In the present study, a convolutional neural network (CNN) architecture is proposed to validate landslide photos collected by citizens or nonexperts and integrated into a mobile- and web-based GIS environment designed specifically for a landslide CitSci project. The VGG16 has been used as the base model since it allows finetuning, and high performance could be achieved by selecting the best hyper-parameters. Although the training dataset was small, the proposed CNN architecture was found to be effective as it could identify the landslide photos with 94% precision. The accuracy o...
The effective mitigation of risk sourced from mass movements requires systematic approaches. In l... more The effective mitigation of risk sourced from mass movements requires systematic approaches. In large mapping scale or single mass movement case risk assessment can be performed based on conventional geotechnical risk assessment methods, either quantitatively or qualitatively However, in medium to large scale mass movement risk assessment, risk zoning is required which is still very difficult. The main reasons are; lack of systematic methods for mapping of hazard, which involves spatial and temporal evaluation of mass movement probability and lack of mapping methods for potential consequences or worth of losses. In this study, a risk assessment method for qualitative zoning of risk is proposed for the debris flow risk in a selected area from the Western Taurid region of Turkey, because the study area is under debris flow threat. The hazard map is prepared by subjective probability assignments of potential debris flow zones in the study region. The potential debris flow zones are obtained by processing aerial photos and field survey data in geographic information system (GIS) framework. Then a thematic hazard map is prepared in GIS with hazard levels of low, medium and high. The second component of risk, which is consequence or worth of loss mapping, is performed by initially identifying the elements at risk in the study region. The region covers two medium scale towns (Uluborlu and Senirkent) and three villages (Yassioren, Ortayazi and Garip), a forested area under protection, which contains endangered trees of Southwestern Turkey, a main road connecting town and villages to the main city of Isparta and an irrigation channel constructed by The State Hydrolic Works (DSI). The boundaries of residential area are obtained by using Google Earth Technology, and RGB true color composite of Landsat ETM
The success rate in landslide susceptibility mapping efforts increased with the advancements in m... more The success rate in landslide susceptibility mapping efforts increased with the advancements in machine learning algorithms and the availability of geospatial data with high spatial and temporal resolutions. Existing data-driven susceptibility mapping models are not globally applicable due to the high variability of landslide conditioning parameters and the limitations in the availability of up-to-date and accurate data. Among numerous applications, landslide susceptibility maps are essential for site selection and health monitoring of engineering structures, such as dams, for increasing their lifetime and to prevent from disastrous events caused by the damages. In this study, landslide susceptibility mapping performance of XGBoost algorithm was evaluated in a landslide-prone area in the upper basin of Ataturk Dam, which is a prime investment located in the southeast of Turkey. The study area has a size of 2718.7 km2 with an elevation difference of ca. 2000 m and contains 27 litholo...
In railway and highway projects, the expansive soils in arid and semi-arid regions are frequently... more In railway and highway projects, the expansive soils in arid and semi-arid regions are frequently encountered. Expansive clays result in serious damages on light structures. However, direct determination of swelling pressure requires time consuming test procedure and sophisticated laboratory equipment. For this reason, some prediction models for swelling properties of expansive soils have always been attractive, but these models are generally statistical based. Therefore, in this study, a simple and feasible method based on linguistic "if-then" rules is developed and proposed for the rapid determination of swelling pressure depending on Atterberg limits and clay content of soils.
In railway and highway projects, the expansive soils in arid and semi-arid regions are frequently... more In railway and highway projects, the expansive soils in arid and semi-arid regions are frequently encountered. Expansive clays result in serious damages on light structures. However, direct determination of swelling pressure requires time consuming test procedure and sophisticated laboratory equipment. For this reason, some prediction models for swelling properties of expansive soils have always been attractive, but these models are generally statistical based. Therefore, in this study, a simple and feasible method based on linguistic "if-then" rules is developed and proposed for the rapid determination of swelling pressure depending on Atterberg limits and clay content of soils.
This paper describes a study into the relationship between volumetric block proportions and uncon... more This paper describes a study into the relationship between volumetric block proportions and unconfined compressive strength (UCS) of Ankara Agglomerate, a volcaniclastic block and tuff matrix mixture containing relatively weak tuff matrix surrounding stronger pink andesite blocks and very strong black andesite blocks. Volumetric block proportions were estimated using image analysis methods. The pink and black andesite blocks in the bimrock exhibited significant color contrasts with the tuff matrix, which facilitated image analysis of grayscale and RGB colored photographs of outcrops. Estimates of block proportions from image analysis were checked against estimates generated using the zero-dimensional "node-counting method". 2D block proportions estimated from measurements of photographs were considered to be equivalent to the volumetric block proportions because the volcanic blocks were approximately equi-dimensional. The measured volumetric block proportions were incorporated into a further stage of the study by developing regression-based equations to estimate the overall uniaxial compressive strength of Ankara Agglomerate as a function of volumetric block proportions. The non-linear relationship between volumetric block proportions and overall UCS of Ankara Agglomerate, suggests a dependence between overall UCS of the bimrock and the strengths of the different types of blocks. This dependence may be due to variations in block/matrix strength contrasts and requires further study. USA 10065 S.W.
Nowadays several scientific disciplines utilize Citizen Science (CitSci) as a research approach. ... more Nowadays several scientific disciplines utilize Citizen Science (CitSci) as a research approach. Natural hazard research and disaster management also benefit from CitSci since people can provide geodata and the relevant attributes using their mobile devices easily and rapidly during or after an event. An earthquake, depending on its intensity, is among the highly destructive natural hazards. Coordination efforts after a severe earthquake event are vital to minimize its harmful effects and timely in-situ data are crucial for this purpose. The aim of this study is to perform a CitSci pilot study to demonstrate the usability of data obtained by volunteers (citizens) for creating earthquake iso-intensity maps in a short time. The data were collected after a 5.8 Mw Istanbul earthquake which occurred on 26 September 2019. Through the mobile app “I felt the quake”, citizen observations regarding the earthquake intensity were collected from various locations. The intensity values in the app...
Urban areas may be affected by multiple hazards, and integrated hazard susceptibility maps are ne... more Urban areas may be affected by multiple hazards, and integrated hazard susceptibility maps are needed for suitable site selection and planning. Furthermore, geological–geotechnical parameters, construction costs, and the spatial distribution of existing infrastructure should be taken into account for this purpose. Up-to-date land-use and land-cover (LULC) maps, as well as natural hazard susceptibility maps, can be frequently obtained from high-resolution satellite sensors. In this study, an integrated hazard susceptibility assessment was performed for a developing urban settlement (Mamak District of Ankara City, Turkey) considering landslide and flood potential. The flood susceptibility map of Ankara City was produced in a previous study using modified analytical hierarchical process (M-AHP) approach. The landslide susceptibility map was produced using the logistic regression technique in this study. Sentinel-2 images were employed for generating LULC data with the random forest cla...
5th International Symposium on Eastern Mediterranean Geology, 2004
On May 21, 1998, a catastrophic mass movement stroke the disseminated Dağköy settlement in the We... more On May 21, 1998, a catastrophic mass movement stroke the disseminated Dağköy settlement in the West Black Sea Region and caused demolishment of several tens of houses and death of many domestic animals. The mass movement occurred on a gentle slope with relatively dense vegetation cover after the 3-day lasted heavy rainfall. The ground material, c.a. 0,6 km 3 of volume that composed of marl and quartzite bedrock and overlying several metres thick soil profile, was removed 600 m downslope, blocked the nearby rivercourse and produced an artificial lake. The analysis of the rainfall data for long and short periods (daily and hourly) clearly indicate that the heavy rainfall was the triggering factor for the landslide. The topography, dip of marl bedding, dense high trees and thick soil horizon developed on top of the marly ground contributed to the event in various degrees. The eyewithness of the villagers and subsequent field observations show that the Dağköy landslide is complex in nature in terms of material transport and deposition. Near the crown, dismembering of the ground into slope-parallel slices and their domino-style sliding and rotation are the dominant processes. Within the central part of the accumulation zone, several enormous (with respect to landslide scale) ground blocks without any internal deformation are embedded in the muddy debris material. The highly plastic debris material is mostly clay and silt grade with lesser amount of disseminated gravels. Restoration of the landslide depicts that these large terrains were transported several hundred metres downslope within the mudflow in a rotational manner. The fringes of the accumulation zone were marked by gravel to boulder-sized angular quartzite blocks without binding fine-grained material, which is a fact sugesting another particular process, the grain flow. As the main causes of this, the mechanic fragmentation in the basal part of the landslide under the thick moving material and a pressure relief towards the fringes were suggested. Lastly, the accumulation zone was slightly gullied by subsequent low viscosity mudflows and fluid flows that deposited mud-sized fans in the very distal reach. As a complex failure and mass movement case, the Dağköy landslide was restored by means of the morphology produced, the nature and distribution of the accumulated facies, and eyewithnes of the villagers. It is concluded that the varying transportation processes from debris flow to massive sliding were determined by the initial conditions such as water content and strength of the material. The dynamic conditions such as shape, velocity and stress distribution of the failure, grinding and mixing of the material also should have played significant roles in the formation and distribution of the processes. Ref: T7-1
5th International Symposium on Eastern Mediterranean Geology, 2004
Turkey, landslides are the second major natural hazard, following earthquakes (Ildir, 1995). For ... more Turkey, landslides are the second major natural hazard, following earthquakes (Ildir, 1995). For this reason, economic losses and causalities sourced from landslides are great. Espe-cially, landslides are frequent in the Black Sea Region of Turkey. Landslides are controlled by two main factors such as conditioning and triggering factors. Geology, topography, vegetation cover, drainage and groundwater conditions etc are accepted as conditioning factors while earthquakes and heavy precipitations are known as the main triggers for landslides. Investi-gation of mechanism and activity of a large and complex landslide, namely Yokuslubag land-slide, is the main purpose of the present study, because descriptions of landslides have great importance for landslide hazard mitigation efforts. For this reason, mechanism and activity of the Yokuslubag landslide are described combining air-photo interpretations, field observations and monitoring data, because the Yokuslubag landslide seems interesting and scientifically valuable. The Yokuslubag locates at south east part of the Black Sea Region (Fig.1). The re-gion has mountainous morphological characters and the Coruh River, the biggest river of the region, locates at the southern part of the landslide being the toe of the landslide. Agglomer-ates, andesites and tuffs, and their weathering products are the main slope-forming material.
5th International Symposium on Eastern Mediterranean Geology, 2004
The term landslide includes a wide range of ground movement, such as slides, falls, flows etc. ma... more The term landslide includes a wide range of ground movement, such as slides, falls, flows etc. mainly based on gravity with the aid of many conditioning and triggering factors. Particularly in the last two decades, there is an increasing international interest on the landslide susceptibil-ity, hazard or risk assessments (Aleotti and Chowdhury, 1999). However, several methods and techniques have been proposed and tested to evaluate landslide assessments, but no general agreement has yet been reached about the methods used to produce such maps (Guzzetti et al., 2000). One of the important stages for the landslide susceptibility mapping is the preparation of the landslide inventory maps. In addition, analyzing the factors conditioning the landslides is also vital. In the present study, it is aimed to evaluate the landslide suscepti-bility using the most relevant conditioning parameters on the landslide occurrence in a se-lected landslide prone area in the West Black Sea region of Turkey. For this purpose, a de-tailed landslide inventory map is prepared and the fuzzy relations are considered to select the most relevant parameters. Results are compared with the factor analysis. Finally, landslide susceptibility maps of the study area are produced using two techniques and performances of the produced maps are discussed.
5th International Symposium on Eastern Mediterranean Geology, 2004
The uniaxial compressive strength of rocks is controlled by many factors such as mineralogy, text... more The uniaxial compressive strength of rocks is controlled by many factors such as mineralogy, texture, porosity, degree of saturation, weathering etc. For this reason, some researchers (Hoshino, 1974; Shea and Kronenberg, 1993; Ulusay et al, 1994 Gokceoglu et al., 1998; Prik-ryl, 2001) proposed some empirical relationships between the uniaxial compressive strength and such petrophysical parameters of the rocks. Besides, it is possible to find some correla-tions between the uniaxial compressive strength and slake durability index (Cargill and Sha-koor, 1990; Koncagul and Santi, 1999). However, these researchers considered two-cycle slake durability index as recommended by ISRM (1981) and ASTM (1990). As stated by Kon-cagul and Santi (1999), Cargill and Shakoor (1990) found a statistically significant correlation between the uniaxial compressive strength and slake durability index. Some researchers (Taylor, 1988; Moon and Beattie, 1995; Ulusay et al., 1995; Bell et al., 1997; Gokceoglu et al. 2000) emphasized that two cycle slake durability testing did not appear to offer an acceptable indication of the durability of clay bearing rocks. For this reason, in this study, the four cycles slake durability index values were considered as proposed by Gokceoglu et al. (2000) when developing the predictive model. In addition, the clay contents of the rock studied were also used as the independent variable of the model. The purpose of the present study proposes a predictive model for estimating the uniaxial compressive strength of the clay-bearing rocks selected from Turkey. When developing the predictive model, the rule-based fuzzy model was taken into consideration.
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Papers by C. Gokceoglu