Implementation of reconstructed geomorphologic units in landslide susceptibility mapping: the Melen Gorge (NW Turkey)

In the international literature, although considerable amount of publications on the landslide susceptibility mapping exist, geomorphology as a conditioning factor is still used in limited number of studies. Considering this factor, the purpose of this article paper is to implement the geomorphologic parameters derived by reconstructed topography in landslide susceptibility mapping. According to the method employed in this study, terrain is generalized by the contours passed through the convex slopes of the valleys that were formed by fluvial erosion. Therefore, slope conditions before landsliding can be obtained. The reconstructed morphometric and geomorphologic units are taken into account as a conditioning parameter when assessing landslide susceptibility. Two different data, one of which is obtained from the reconstructed DEM, have been employed to produce two landslide susceptibility maps. The binary logistic regression is used to develop landslide susceptibility maps for the Melen Gorge in the Northwestern part of Turkey. Due to the high correct classification percentages and spatial effectiveness of the maps, the landslide susceptibility map comprised the reconstructed morphometric parameters exhibits a better performance than the other. Five different datasets are selected randomly to apply proper sampling strategy for training. As a consequence of the analyses, the most proper outcomes are obtained from the dataset of the reconstructed topographical parameters and geomorphologic units, and lithological variables that are implemented together. Correct classification percentage and root mean square error (RMSE) values of the validation dataset are calculated as 86.28% and 0.35, respectively. Prediction capacity of the different datasets reveal that the landslide susceptibility map obtained from the reconstructed parameters has a higher prediction capacity than the other. Moreover, the landslide susceptibility map obtained from the reconstructed parameters produces logical results

Medium-scale hazard mapping for shallow landslide initiation: the Buyukkoy catchment area (Cayeli, Rize, Turkey)

The main purpose of this study is to develop a new hazard evaluation technique considering the current limitations, particularly for shallow landslides. For this purpose, the Buyukkoy catchment area, located in the East Black Sea Region in the east of Rize province and the south of Cayeli district, was selected as the study area. The investigations were executed in four different stages. These were (1) preparation of a temporal shallow landslide inventory of the study area, (2) assessment of conditioning factors in the catchment, (3) susceptibility analyses and (4) hazard evaluations and mapping. A total of 251 shallow landslides in the period of 1955-2007 were recognised using different data sources. A 'Sampling Circle' approach was proposed to define shallow landslide initiation in the mapping units in susceptibility evaluations. To accomplish the susceptibility analyses, the method of artificial neural networks was implemented. According to the performance analyses conducted using the training and testing datasets, the prediction and generalisation capacities of the models were found to be very high. To transform the susceptibility values into hazard rates, a new approach with a new equation was developed, taking into account the behaviour of the responsible triggering factor over time in the study area. In the proposed equation, the threshold value of the triggering factor and the recurrence interval are the independent variables. This unique property of the suggested equation allows the execution of more flexible and more dynamic hazard assessments. Finally, using the proposed technique, shallow landslide initiation hazard maps of the Buyukkoy catchment area for the return periods of 1, 2, 5, 10, 50 and 100 years were produced

Safety assessment of limestone-based engineering structures to be partially flooded by dam water: A case study from northeastern Turkey

Turkey has been faced with an escalating energy demand and recurring droughts within the last few decades. The construction of the BAGISTAS 1 Hydroelectric Power Plant Dam, one of the dams constructed in order to solve these problems, resulted in the partial submersion of a number of pre-existing railway bridges and retaining walls of the Divrigi-Ilic-Erzincan Railway System (NE Turkey). Before the accumulation of dam water, the structural safety of these 86-year-old infrastructures, which were constructed using carbonate rocks, were investigated under saturated conditions. The maximum uniaxial compressive strength (UCS) losses under saturated conditions, after the application of freezing-thawing, and after wetting-drying cycles, were determined. For the mortar samples obtained from a drill core, the wet-to-dry UCS ratio was determined to be 0.82, suggesting a high durability performance. The natural filling material, which was used behind the retaining structures and as the railway embankment, was classified as the selective filling material, representing the best conditions for a filling material. The samples representing the retaining wall and filling materials had very high slake durability indexes, showing that they are very durable under the effect of water. The closed-form analysis for partially submerged retaining walls indicated that the structures are safe against overturning and have permissible internal wall stresses under operational conditions. In addition, the structural safety assessment of a masonry bridge was investigated using 3D Finite Element Modeling (FEM) under the designed train and expected earthquake loads, in both dry and partly immersed conditions. The results of the study showed that the strength reduction of masonry in saturated conditions, under the raised waters of the newly constructed dam, has an insignificant effect on the submerged sections and does not pose any danger to the overall structural performance

An application of adaptive neuro fuzzy inference system for estimating the uniaxial compressive strength of certain granitic rocks from their mineral contents

WOS: 000311133600012The uniaxial compressive strength (UCS) of rocks is an important intact rock parameter, and it is commonly used for various engineering applications. This parameter is mainly controlled by the mineralogical and textural characteristics of rocks. In this study, a soft computing method, an adaptive neuro-fuzzy inference system (ANFIS), was employed to estimate UCS from the mineral contents of certain granitic rocks selected from Turkey; nonlinear multiple regression analysis was then employed to validate these estimations. Five nonlinear multiple regressions and ANFIS models were constructed with three inputs: quartz, orthoclase and plagioclase. To determine the optimal model, various performance indices (R, values account for and root mean square error) were determined, and the model obtained from dataset #3 was selected as the optimal model. The coefficients of correlation for the nonlinear multiple regression and ANFIS models were 0.87 and 0.91, respectively. Thus, both models yielded acceptable results, and the ANFIS is a suitable method for estimating the UCS of rocks. (C) 2012 Elsevier Ltd. All rights reserved

Evidence of orbital forcing in lake-level fluctuations in the Middle Eocene oil shale-bearing lacustrine successions in the Mudurnu-Goynuk Basin, NW Anatolia (Turkey)

Mudurnu-Goynuk basin of the Sakarya Zone in NW Anatolia comprises ca. 1500 m thick Paleocene-Eocene terrestrial to shallow marine succession overlying the Late Cretaceous deeper marine progradational fore-arc sediments. Formed in a foreland setting in relation to southerly situated izmir-Ankara suture zone, this terrestrial succession (regionally known as Kizilcay group) comprises a thin (<200 m) oil shale-bearing lacustrine section with very good cyclic patterns that potentially serves the quantification of stratigraphy and enlightening the origin of cyclicities of various hierarchy. Our detailed fades analysis on three correlative measured sections showed that mudstone, oil shale and thinner limestone alternations characterize the relatively deeper part of the Eocene lake with probable marine intervention, while thicker limestone, coal, marl and occasional oil shale alternations typify the southern relatively freshwater shoal areas. These facies are frequently organized as meter-scale symmetric to asymmetric transgressive-regressive cycles. Spectral analysis of the mudstone beds and the cycles within the lacustrine succession strongly indicates the occurrence of full bands of Milankovitch with the shortest precession cycle (19 ka) at ca. 2.30 m. Our observations further revealed quite rhythmic thin couplets with estimated durations of 365-730 yr that might represent abrupt climatic changes during deposition. On the other hand, longer duration (ca. 1 Ma) of shoaling and deepening trends in the studied sections were attributed basically to varying subsidence due to tectonic loading in the southerly suture zone. Lastly, regarding the distribution of depositional environments we propose that the oil shale exploration activities should be carried out within a 20 km wide E-W running belt while the southern limits of this belt is more prolific for coal resources

Batı Karadeniz Bölgesinde Seçilmiş Üç Farklı Havzanın Akma ve Kayma Duyarlılıklarının Ayrı Ayrı Değerlendirilmesi,

Erdoğan Yüzer Mühendislik Jeolojisi Sempozyum