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    Automatic Detection and Mapping of Dolines Using U-Net Model from Orthophoto Images
    (Mdpi, 2023) Polat, Ali; Keskin, Inan; Polat, Ozlem
    A doline is a natural closed depression formed as a result of karstification, and it is the most common landform in karst areas. These depressions damage many living areas and various engineering structures, and this type of collapse event has created natural hazards in terms of human safety, agricultural activities, and the economy. Therefore, it is important to detect dolines and reveal their properties. In this study, a solution that automatically detects dolines is proposed. The proposed model was employed in a region where many dolines are found in the northwestern part of Sivas City, Turkey. A U-Net model with transfer learning techniques was applied for this task. DenseNet121 gave the best results for the segmentation of the dolines via ResNet34, and EfficientNetB3 and DenseNet121 were used with the U-Net model. The Intersection over Union (IoU) and F-score were used as model evaluation metrics. The IoU and F-score of the DenseNet121 model were calculated as 0.78 and 0.87 for the test data, respectively. Dolines were successfully predicted for the selected test area. The results were converted into a georeferenced vector file. The doline inventory maps can be easily and quickly created using this method. The results can be used in geomorphology, susceptibility, and site selection studies. In addition, this method can be used to segment other landforms in earth science studies.
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    Kinematic Analysis and Rockfall Assessment of Rock Slope at the UNESCO World Heritage city (Safranbolu/Turkey)
    (Springer Int Publ Ag, 2022) Keskin, Inan; Polat, Ali
    Rockfall is one of the most significant natural hazards affecting human life. Preparing and triggering natural factors of rockfalls caused by geological conditions, in general, are mainly earthquakes, precipitation, freeze-thaw, physical and chemical weathering, joints in the rock mass, tree roots, etc. Initial velocity, weight, type and shape of the falling rock as well as the type of rock forming the slope mainly control the characteristics of boulder falling. This paper deals with rockfalls affecting Safranbolu, a UNESCO World Heritage site in Turkey. Scan-line surveys were performed to define the geologic properties of the limestone rock mass and joint properties in the study area. Kinematic analyses have been made for the slopes in the study area, considering the main joint sets, and failure potentials have been determined. A series of rockfall simulations were carried out using computer software, and rockfall zone maps were created with kinetic energy, bounce height, horizontal location of rock endpoints and velocity of the rocks.
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    Preventing and Analysis of Falling Rocks: A Case of Sarica Village (Gurun, Turkey)
    (Springer India, 2016) Polat, Ali; Keskin, Inan; Denizli, Irfan
    Rock fall is a common natural hazard causing significant damage to infrastructure and loss of life and property. This paper describes selection of prevention method, construction processes and the results of a rockfall hazard assessment for the village of Sarica (Gurun region, Turkey) based on an engineering-geological model. The study area is located on the lower parts of an area with very steep cliffs and 40-500 slopes with fractured sedimentary and volcanic rocks. Detailed studies have been conducted in the region to prevent the risk of any rockfalls. Maps and charts are prepared including the rock blocks that are likely to fall and the related housing area under the risk. It was found that block sizes reached 3 m(3). Rockfall analyses were performed along the selected profiles using the Rocfall V.5.0 software. Kinetic energy, bounce height, horizontal location of rock end-points and velocity of the rocks along each section were evaluated separately for each profile. This data was used to select design and construction of rockfall preventing system. In this study professional type rock fall barrier (catchment fence) was used. This method was chosen because it was cheaper, more practical and reliable than others.