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    Landslide-Triggering Factors in Korucak Subbasin, North Anatolian, Turkey
    (ELSEVIER SCIENCE BV, 2015) Altin, Turkan Bayer; Gokkaya, Ergin; Drusa, M; Marschalko, M; Yilmaz, I; Segallini, A; Ferrero, AM; Bednarik, M
    Korucak Creek Basin is located within upper course of the Yesilirmak River Basin and southern Middle Karadeniz (Black Sea) section which is known to have the potential of landslide and flood risk. The purpose of identification of landslide-triggering factors is to highlight the regional distribution of potentially unstable slopes and to guide decision makers for regional planning purposes. We assessed morphometric parameters for landslide-triggering factors of Korucak Creek Basin using GIS (Geographical Information System). These parameters are Stream Power Index (SPI) and Compound Topographic Index (CTI). Moreover, slope and elevation values of the basin were classified and superposed over the geologic map. Landslide locations were identified from topographic maps and verified with field observation. The total catchment area of the basin is about 55 km2. More than half of the total basin is covered by metamorphic rock types such as schist, which has high permeability and weakness against erosion and is one of the main causes of the landslides. The results show that the main triggering factors are slope and lithology. Thus, northern and western of the Korucak subbasin are under the highest-risk landslide areas. (C) 2015 The Authors. Published by Elsevier B.V.
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    Spatial and Temporal Patterns of Land Subsidence and Sinkhole Occurrence in the Konya Endorheic Basin, Turkey
    (Mdpi, 2024) Orhan, Osman; Haghshenas Haghighi, Mahmud; Demir, Vahdettin; Gokkaya, Ergin; Gutierrez, Francisco; Al-Halbouni, Djamil
    The endorheic Konya Basin is a vast aggradational plain in Central Anatolia, Turkiye. It occupies a significant portion of Konya Province, covering approximately 50,000 km2. The basin is subjected to intense groundwater withdrawal and extensive agricultural activities with excessive irrigation. These activities have led to human-induced hazards, such as sinkholes and regional land subsidence. Although sinkhole occurrence mainly occurs in the Karapinar area, land subsidence is primarily observed in the central sector of Konya city, with 2 million inhabitants, as well as in various parts of the basin. This study focuses on determining the extent and rate of land subsidence throughout the basin, understanding sinkhole formation, and unraveling their relationship with anthropogenic activities. For this purpose, Interferometric Synthetic Aperture Radar (InSAR) analysis of Sentinel-1 data from 2014 to 2022 was conducted to identify and assess land subsidence. We also used the land cover data and groundwater-level information to better understand the spatial and temporal patterns of land subsidence and sinkhole occurrence. Additionally, the land cover data were used to resolve spatial-temporal variations in the cultivated area and urbanization, which are the main factors governing groundwater exploitation in the region. Our study identified widespread subsidence zones with rates as high as 90 mm/y. Groundwater overexploitation to sustain extensive agricultural operations is the main cause of the high rate of land subsidence. Additionally, it was discovered that the number of sinkholes has substantially increased due to anthropogenic influences, currently amounting to as many as 660.
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    Tectonic geomorphology and deep-seated gravitational slope deformations (DSGSDs) in the Acigol Graben, Turkiye
    (Elsevier, 2024) Tuncel, Esra; Gutierrez, Francisco; Gokkaya, Ergin; Seyitoglu, Guerol; Cicek, Ihsan
    The Sogut Mountains is a fault-bounded carbonate range situated between the active Acigol and Akgol grabens in southwestern Turkiye. The southwestern sector of the Acigol Graben floor displays an array of faults that have produced peculiar intra-basin half-grabens with local lakes and drainages. The conspicuous geomorphic expression of the intra-basin faults and depressions in this sector of the basin is attributed to low sedimentation rate (i.e., starved basin) related to very limited runoff and sediment supply from the southwestern carbonate margin of the basin, dominated by subsurface drainage in a carbonate bedrock strongly affected by gravitational deformation and karstification. Detailed mapping reveals the presence of large landslides and extensive DSGSDs in the mountain fronts flanking the Sogut Mountains, showing ridge-top depression, uphill-facing scarps, highrelief downhill-facing scarps, and toe bulges. Cartographic relationships provide insights into the development and evolution of the deformations in the slopes that experience continuous tectonic rejuvenation and debuttressing. DSGSDs and large landslides take advantage of secondary synthetic tectonic faults, in which gravitational and tectonic displacement are superposed. The transformation of DSGSDs into large to giant short runout landslides (up to ca. 3.5 Gm(3)) occurs mainly on laterally unconfined slopes associated with bends and stepovers in the basin-bounding faults. Seismicity is likely the main triggering factor controlling the kinematics of the gravitational deformations and landslides. Cartographic evidence indicate downslope propagation of the gravitational deformation (uphill-facing-scarps and associated troughs) in the tectonically growing slopes. Additionally, preferential development of solution sinkholes is observed in gravitationally distorted slopes with impeded surface drainage.