New layout for the diversion of the upper Filyos Basin water supply in Ankara

The domestic water demand of Ankara, the capital city of Turkey, is largely supplied from dams located in the Sakarya basin, the additional 10% being obtained from groundwater. It is believed that this system has the capacity to satisfy the water demands of the city until 2002. To provide for the additional water requirements of the city up to 2020, important projects have been undertaken in the adjacent Upper Filyos and Kizilirmak basins since the 1960s. The philosophy behind the projects was to collect water from the Upper Filyos basin to be stored in the Isikli dam and then transferred to Ankara. All the alternatives studied were based on the transfer of water from the Isikli dam to Ankara via the Camlidere dam located in the Sakarya basin (Köroglu water transmission system). However, this would involve crossing the Köroglu mountain range which separates the two basins, using such large-scale engineering structures as tunnels, shafts, access tunnels and cut and cover works. With the proximity of the North Anatolia Fault Zone, the poor engineering characteristics of the ground conditions and the high groundwater level were important factors to be taken into consideration. Water from the Akyar, Egrekkaya and Kurtbogazi dams situated to the north of the city follows the same route, whereas from Çamlidere to the treatment plant at Ankara the water is transferred by a different line. The proposed alternative transfers the water from the Upper Filyos basin directly into the Akyar-Egrekkya- Kurtbogazi water transmission system by use of a pipeline - the E5 water transmission system. The total length of this pipeline is 36 km, of which 21 km runs from the Isikli dam to the topographic divide of the Köroglu mountains. This alternative: (1) takes place along the E5 state road; (2) avoids potential geotechnical problems; (3) does not require any tunnel, except a cut and cover section of about 700 m; (4) can provide secondary energy at the downstream part of the Akyar dam; and (5) is superior to the previous alternatives with regard to cost, timing, environmental protection and safety/security

The 17 March 2005 Kuzulu landslide (Sivas, Turkey) and landslide-susceptibility map of its near vicinity

Landslides are common natural hazards in the seismically active North Anatolian Fault Zone of Turkey. Although seismic activity, heavy rainfall, channel incisions, and anthropogenic effects are commonly the main triggers of landslides, on March 17, 2005, a catastrophic large landslide in Sivas, northeastern of Turkey, the Kuzulu landslide, was triggered by snowmelt without any other precursor. The initial failure of the Kuzulu landslide was rotational. Following the rotational failure, the earth material in the zone of accumulation exhibited an extremely rapid flow caused by steep gradient and high water content. The Agnus Creek valley, where Kuzulu village is located, was filled by the earth-flow material and a landslide dam was formed on the upper part of Agnus Creek. The distance from the toe of the rotational failure down to the toe of the earth flow measured more than 1800 m, with about 12.5 million m3 of displaced earth material. The velocity of the Kuzulu landslide was extremely fast, approximately 6 m/s. The main purposes of this study are to describe the mechanism and the factors conditioning the Kuzulu landslide, to present its environmental impacts, and to produce landslide-susceptibility maps of the Kuzulu landslide area and its near vicinity. For this purpose, a detailed landslide inventory map was prepared and geology, slope, aspect, elevation, topographic-wetness index and stream-power index were considered as conditioning factors. During the susceptibility analyses, the conditional probability approach was used and a landslide-susceptibility map was produced. The landslide-susceptibility map will help decision makers in site selection and the site-planning process. The map may also be accepted as a basis for landslide risk-management studies to be applied in the study area. © 2005 Elsevier B.V. All rights reserved

Susceptibility assessments of shallow earthflows triggered by heavy rainfall at three catchments by logistic regression analyses

Sometimes regional meteorological anomalies trigger different types of mass movements. In May 1998, the western Black Sea region of Turkey experienced such a meteorological anomaly. Numerous residential and agricultural areas and engineering lifelines were buried under the flood waters. Besides the reactivation of many previously delineated landslides, thousands of small-scale landslides (mostly the earthflow type) occurred all over the region. The earthflows were mainly developed in flysch-type units, which have already presented high landslide concentrations. In this study, three different catchments - namely Agustu, Egerci, and Kelemen - were selected because they have the most landslide-prone geological units of the region. The purposes of the present study are to put forward the spatial distributions of the shallow earthflows triggered, to describe the possible factors conditioning the earthflows, and to produce the shallow earthflow susceptibility maps of the three catchments. The unique condition units (UCU) were employed during the production of susceptibility maps and during statistical analyses. The unique condition units numbered 4052 for the Agustu catchment, 13,241 for the Egerci catchment and 12,314 for the Kelemen catchment. The earthflow intensity is the highest in the Agustu catchment (0.038 flow/UCU) and lowest in the Egerci catchment (0.0035 flow/UCU). Logistic regression analyses were also employed. However, during the analyses, some difficulties were encountered. To overcome the difficulties, a series of sensitivity analyses were performed based on some decision rules introduced in the present study. Considering the decision rules, the proper ratios of UCU free from earthflow (0)/UCU including the earthflow (1) for the Agustu, Egerci and Kelemen catchments were obtained as 3, 6, and 5, respectively. Also, a chart for the proper ratio selection was developed. The regression equations from the selected ratios were then applied to the entire catchment and the earthflow susceptibility maps were produced. The landslide susceptibility maps revealed that 15% of the Agustu catchment, 8% of the Egerci catchment, and 7% of the Kelemen catchment have very high earthflow susceptibility; and most of the earthflows triggered by the May 1998 meteorological event were found in the very high susceptibility zones. © 2005 Elsevier B.V. All rights reserved

Application of logistic regression for landslide susceptibility zoning of Cekmece Area, Istanbul, Turkey

As a result of industrialization, throughout the world, cities have been growing rapidly for the last century. One typical example of these growing cities is Istanbul, the population of which is over 10 million. Due to rapid urbanization, new areas suitable for settlement and engineering structures are necessary. The Cekmece area located west of the Istanbul metropolitan area is studied, because the landslide activity is extensive in this area. The purpose of this study is to develop a model that can be used to characterize landslide susceptibility in map form using logistic regression analysis of an extensive landslide database. A database of landslide activity was constructed using both aerial-photography and field studies. About 19.2% of the selected study area is covered by deep-seated landslides. The landslides that occur in the area are primarily located in sandstones with interbedded permeable and impermeable layers such as claystone, siltstone and mudstone. About 31.95% of the total landslide area is located at this unit. To apply logistic regression analyses, a data matrix including 37 variables was constructed. The variables used in the forwards stepwise analyses are different measures of slope, aspect, elevation, stream power index (SPI), plan curvature, profile curvature, geology, geomorphology and relative permeability of lithological units. A total of 25 variables were identified as exerting strong influence on landslide occurrence, and included by the logistic regression equation. Wald statistics values indicate that lithology, SPI and slope are more important than the other parameters in the equation. Beta coefficients of the 25 variables included the logistic regression equation provide a model for landslide susceptibility in the Cekmece area. This model is used to generate a landslide susceptibility map that correctly classified 83.8% of the landslide-prone areas. © 2006 Springer-Verlag

A probabilistic seismic hazard assessment for the Turkish territory: part II—fault source and background seismicity model

Over the years, several local and regional seismic hazard studies have been conducted for the estimation of the seismic hazard in Turkey using different statistical processing tools for instrumental and historical earthquake data and modeling the geologic and tectonic characteristics of the region. Recently developed techniques, increased knowledge and improved databases brought the necessity to review the national active fault database and the compiled earthquake catalogue for the development of a national earthquake hazard map. A national earthquake strategy and action plan were conceived and accordingly with the collaboration of the several institutions and expert researchers, the Revision of Turkish Seismic Hazard Map Project (UDAP-Ç-13-06) was initiated, and finalized at the end of 2014. The scope of the project was confined to the revision of current national seismic hazard map, using the state of the art technologies and knowledge of the active fault, earthquake database, and ground motion prediction equations. The following two seismic source zonation models are developed for the probabilistic earthquake hazard analysis: (1) Area source model, (2) Fault and spatial smoothing seismic source model (FSBCK). In this study, we focus on the development and the characterization of the Fault Source model, the background spatially smoothed seismicity model and intrinsic uncertainty on the earthquake occurrence-rates-estimation. Finally, PSHA results obtained from the fault and spatial smoothed seismic source model are presented for 43, 72, 475 and 2475 years return periods (corresponding to 69, 50, 10, and 2% probability of exceedance in 50 years) for PGA and 5% damped spectral accelerations at 0.2 and 1.0 s. © 2017, Springer Science+Business Media Dordrecht.Acknowledgements First, we would like to express our gratitude to Sinan Akkar for his kind coordination of the project titled as ‘‘The update of the seismic hazard maps of Turkey’’, and to Mustafa Erdik for his suggestions and comments, which helped us to considerably improve the project. We would like to thank various local researchers who gave us feedback and comments: Tolga Yılmaz, Ahmet Yakut, from Middle East Technical University; Murat Utkucu from Sakarya University. We also acknowledge Laurentiu Danciu from ETHZ, Roberto Basili from INGV, and Tuba Eroglu Azak who wrote and improved the codes and some scripts used in the calculation of some parameters. The study has been sponsored by AFAD (Disaster and Emergency Management Authority of Turkey) under Project Code UDAP-C¸ -13-16. We would also like to thank Dr. Baumont for his review and suggestions for the improvement of the manuscript

A geohazard reconnaissance study based on geoscientific information for development needs of the western region of Istanbul (Turkey)

The role of geoenvironmental information is becoming increasingly important as legislative changes have forced developers and planning authorities to consider more implications and impact on the environment of large-scale development initiatives. Therefore, integration of surface and subsurface geoscientific information for development needs has prime importance and provides a means of identifying potential problems and opportunities at an early stage in any planned development. However, from the experience of recent natural disasters, it is evident that this was not case the taken into consideration in many countries. In addition to thousands of casualties, many urbanized areas, industrial districts and large-scale engineering structures suffered severe damages from the natural hazards due to many reasons including the lack of preliminary engineering geological maps and zoning maps of the settlement areas. Turkey is one of the countries which is exposed to natural hazards such as earthquakes, landslides and floods. In particular, the devastating 1999 Kocaeli earthquake, which affected the Marmara Region of Turkey, focused the attention on densely urbanized and industrialized metropolitan areas such as Istanbul. The rapid growth of Istanbul, particularly towards west with minimal geoscientific information resulted in an overwhelming pressure on the natural environment. In addition, a large earthquake, which is expected to occur in the Marmara Sea within the next 30 years, also pose a threat to the city and its surroundings. In this study, on the basis of the geological, geomorphological and geophysical reconnaissance study, an integrated geoscientific data were collected from the western region of Istanbul and evaluated for geohazards. The paper focuses on the geological and geomorphological aspects that control the occurrence of some geohazards such as earthquake-induced liquefaction, landslides and flooding. In this context, the geological map of the region was revised and Quaternary deposits were classified into 11 units, in detail. Liquefaction-prone areas were evaluated by using geomorphological criteria based on field investigation, by the examination of the available records from 88 boreholes drilled on recent deposits and by the data from resistivity profiles. The landslides within the region were classified according to their type, relative depth and activity. In addition, fluvial and marine flood-prone areas were also delimited within the region. Finally, a series of maps such as landslide inventory maps, and maps showing liquefaction- and flood-prone areas were produced with the aid of Geographic Information Systems (GIS) to assist in designing further detailed site investigations and to reduce costs by ensuring a more focused approach to strategic planning and site selection. © Springer-Verlag 2005.Mount Allison UniversityAcknowledgements This study was supported by the General Directorate of Mineral Research and Exploration (MTA) of Turkey. The authors gratefully acknowledged MTA for the support provided. The authors also express their sincere thanks to the geophysical team of the MTA for their kind effort in providing the data during resistivity surveys, and General Directorate of Turkish State Hydraulic Works, General Directorate of Turkish Highways and municipalities in the study area

A probabilistic seismic hazard assessment for the Turkish territory—part I: the area source model

The seismic zoning map of Turkey that is used in connection with the national seismic design code (versions issued both in 1997 and 2007) is based on a probabilistic seismic hazard assessment study conducted more than 20 years ago (Gülkan et al. in En son verilere göre hazırlanan Türkiye deprem bölgeleri haritası, Report No: METU/EERC 93-1, 1993). In line with the efforts for the update of the seismic design code, the need aroused for an updated seismic hazard map, incorporating recent data and state-of-the-art methodologies and providing ground motion parameters required for the construction of the design spectra stipulated by the new Turkish Earthquake Design Code. Supported by AFAD (Disaster and Emergency Management Authority of Turkey), a project has been conducted for the country scale assessment of the seismic hazard by probabilistic methods. The present paper describes the probabilistic seismic hazard assessment study conducted in connection with this project, incorporating in an area source model, all recently compiled data on seismicity and active faulting, and using a set of recently developed ground motion prediction equations, for both active shallow crustal and subduction regimes, evaluated as adequately representing the ground motion characteristics in the region. The area sources delineated in the model are fully parameterized in terms of maximum magnitude, depth distribution, predominant strike and dip angles and mechanism of possible ruptures. Resulting ground motion distributions are quantified and presented for PGA and 5 % damped spectral accelerations at T = 0.2 and 1.0 s, associated with return periods of 475 and 2475 years. The full set of seismic hazard curves was also made available for the hazard computation sites. The second part of the study, which is based on a fault source and smoothed seismicity model is covered in Demircioglu et al. in Bull Earthq Eng, (2016). © 2016, Springer Science+Business Media Dordrecht.Acknowledgments We would like to express our gratitude to Sinan Akkar for having initiated this collaborative effort for the update of the seismic hazard maps of Turkey, to Mustafa Erdik for his invaluable suggestions and guidance throughout the study, and to the participants of the various work packages for their active contributions to the discussions during the course of the project. The study has been sponsored by AFAD (Disaster and Emergency Management Authority of Turkey) under Project Code UDAP-C¸ -13-16. We would also like to thank Gabriele Ameri for his review and suggestions for the improvement of the manuscript

Active fault database of Turkey

We have updated the active fault map of Turkey and built its database within GIS environment. In the study, four distinct active fault types, classified according to geochronological criteria and character, were delineated on the 1:25,000 base map of Turkey. 176 fault segments not included in the former active fault map of Turkey, have been identified and documented. We infer that there are 485 single fault segments which are substantially potential seismic sources. In total 1964 active-fault base-maps were transferred into the GIS environment. Each fault was attributed with key parameters such as class, activity, type, length, trend, and attitude of fault plane. The fault parameters are also supported by slip-rate and seismogenic depth inferred from available GPS, seismological and paleoseismological data. Additionally, expected maximum magnitude for each fault segment was estimated by empirical equations. We present the database in a parametric catalogue of fault segments to be of interest in earthquake engineering and seismotectonics. The study provides essential geological and seismological inputs for regional seismic hazard analysis of all over Turkey and its vicinity. © 2016, Springer Science+Business Media Dordrecht.Mount Allison UniversityAcknowledgements This work was carried out as the ‘Updating of Active Fault Map of Turkey and its Database’ project supported by the General Directorate of Mineral Research and Exploration (MTA) between 2004 and 2011. We gratefully acknowledge the MTA for the support provided. Also we would like to thank the reviewers for their comments that improved the paper. The active fault base maps are accessible on the Earth Science Map Portal of the MTA (http://yerbilimleri.mta.gov.tr)

Landslide inventory of northwestern Anatolia, Turkey

Turkey is heavily exposed to natural hazards such as earthquakes, landslides and floods. The total loss caused by landslides in terms of affected buildings, in a period of 35 years between 1959 and 1994, constitutes 27% of the entire loss from all natural hazards and is second after earthquakes. There are no other available data on either direct or indirect losses due to landslides on a national scale. The General Directorate of Mineral Research and Exploration (MTA) started the 'Turkish Landslide Inventory Mapping Project' in 1997 to improve understanding of regional and national landslide processes. The purpose of the project is to establish landslide inventory maps at medium (1:25,000), regional (1:100,000) and national (1:500,000) scales. Existing landslides are mapped on 1:25,000 scale topographic base maps by interpretation of aerial photographs and field investigations. The base maps are then digitized and stored in a geographic information system (GIS) database by the Geological Research Department of MTA. Hence, regional- and national-scale landslide maps will be available as well, as the work progresses. Landslides are classified as fall, topple, slide and flow and are broadly characterized as active or inactive. The landslides are also classified according to their relative depths, as shallow (depth<5 m) and deep-seated (depth>5 m). The present paper will attempt to describe the project standards and its application to the area of 1:500,000 scale Zonguldak quadrangle. The study area extends to 39,081 km2, and 7.1% of the area was found to be affected by landslides. A total 10,007 landslides (392 shallow-seated, 8020 deep-seated active and 1595 deep-seated inactive) were mapped in the area covering 2768 km2. Cretaceous flysch, Paleocene-Eocene flysch and Paleocene-Middle Miocene volcanics are the most landslide-prone units and constitute 27.8%, 29.9% and 7.2% of the all landslides, respectively. © 2004 Elsevier B.V. All rights reserved.Mount Allison UniversityThis work is done as a part of ‘The Turkish Landslide Inventory Mapping Project’ supported by the General Directorate of Mineral Research and Exploration (MTA). The authors gratefully acknowledge MTA for the support provided