Saffet Erdoğan

Harran University

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İT

İbrahim Tiryakioğlu

Afyon Kocatepe University

Engīn Gülal

Yıldız Technical University

Turan Erden

Istanbul Technical University

Hakan Yavaşoğlu

Istanbul Technical University

Fatih Taktak

Usak University

Tamer Baybura

Afyon Kocatepe University

Ergin Tarı

Istanbul Technical University

Serdar Bilgi

Istanbul Technical University

Ali Kazım Telli

Yıldız Technical University

Himmet Karaman

Istanbul Technical University

Cooperative Institutions

Afyon Kocatepe University

Istanbul Technical University

Yıldız Technical University

Harran University

Massachusetts Institute of Technology

Scientific and Technological Research Council of Turkey

Süleyman Demirel University

Suleyman Demirel University

Karadeniz Technical University

Planetary Science Institute

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A comparision of interpolation methods for producing digital elevation models at the field scale

Earth Surface Processes and Landforms (2009)

Saffet Erdoğan

Abstract Digital elevation models have been used in many applications since they came into use in the late 1950s. It is an essential tool for applications that are concerned with the Earth's surface such as hydrology, geology, cartography, geomorphology, engineering applications, landscape architecture and so on. However, there are some differences in assessing the accuracy of digital elevation models for specific applications. Different applications require different levels of accuracy from digital elevation models. In this study, the magnitudes and spatial patterning of elevation errors were therefore examined, using different interpolation methods. Measurements were performed with theodolite and levelling. Previous research has demonstrated the effects of interpolation methods and the nature of errors in digital elevation models obtained with indirect survey methods for small‐scale areas. The purpose of this study was therefore to investigate the size and spatial patterning of errors in digital elevation models obtained with direct survey methods for large‐scale areas, comparing Inverse Distance Weighting, Radial Basis Functions and Kriging interpolation methods to generate digital elevation models. The study is important because it shows how the accuracy of the digital elevation model is related to data density and the interpolation algorithm used. Cross validation, split‐sample and jack‐knifing validation methods were used to evaluate the errors. Global and local spatial auto‐correlation indices were then used to examine the error clustering. Finally, slope and curvature parameters of the area were modelled depending on the error residuals using ordinary least regression analyses. In this case, the best results were obtained using the thin plate spline algorithm. Copyright © 2009 John Wiley & Sons, Ltd.

Elevation (ballistics)

Interpolation

Inverse distance weighting

10.1002/esp.1731

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Citations (153)

Modeling crop yield potential of Eastern Anatolia by using geographically weighted regression

Archives of Agronomy and Soil Science (2009)

Murat Olgun Saffet Erdoğan

Abstract Wheat is a very important cereal crop in Eastern Anatolia in terms of acreage and production. It is a staple food and plays an important role in people's livelihood. Drought often occurs in the region and it dramatically influences wheat yield. The yield also depends upon prevailing climatic conditions, rainfall, temperature and humidity. Crop-modeling studies to forecast crop yield are important not only for people now but for planning studies and precautionary measures for the future. Traditional decision support systems based on crop simulation models are normally site-specific. In order to address the effect of spatial variability of weather variables on crop production, we modeled wheat yield potential on certain climatic conditions by using Geographically Weighted Regression and Geographical Information Systems in Eastern Anatolia in Turkey. Keywords: climateGISmodelingwheatyieldGWR

Geographically Weighted Regression

10.1080/03650340802478807

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Citations (4)

Modelling the spatial distribution of DEM error with geographically weighted regression: An experimental study

Computers & Geosciences (2009)

Saffet Erdoğan

Elevation (ballistics)

Interpolation

Ordinary least squares

Least-squares function approximation

10.1016/j.cageo.2009.06.005

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Citations (73)

A GIS-based assessment of long-term traffic accidents using spatiotemporal and empirical Bayes analysis in Turkey

Applied Geomatics (2022)

Saffet Erdoğan Mehmet Ali Dereli̇Halil İ̇brahim ŞENOL

Traffic accident

Statistical Analysis

10.1007/s12518-022-00419-1

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Citations (7)

GPS constraints on active deformation in the Isparta Angle region of SW Turkey

Geophysical Journal International (2013)

İbrahim Tiryakioğlu Michael Floyd Saffet Erdoğan Engīn Gülal Semih Ergintav

We use survey and continuous GPS observations during the period 1997–2010 to investigate active deformation in the Isparta Angle region of SW Anatolia, Turkey. This region, bordered by the Fethiye Burdur Fault Zone (FBFZ) in the west and the SE extension of the Aksehir Simav Fault Zone (AKSFZ) in the east, accommodates a part of the active deformation of W Turkey. Our results show that the Isparta Angle region rotates counter-clockwise (CCW) with respect to Anatolia. Both the FBFZ and the AKSFZ are predominantly transtensional boundaries that accommodate southward motion of the Isparta region with respect to Anatolia. The FBFZ has left-lateral strike-slip behaviour along its SW segment that changes to right-lateral strike-slip along its NE extension. This change in the sense of strike-slip motion is accommodated by extension on a NW–SE striking normal fault system that is associated with the Menderes Graben system. Transtensional fault systems along the boundaries of the Isparta Angle with Anatolia are inconsistent with extrusion models for present-day southward motion. An increase in motion rates towards the Hellenic and Cyprus arc subduction systems, and CCW of the Isparta region, supports dynamic models involving active rollback of the subducting African Plate, toroidal mantle flow around the eastern edge of the subducting African slab near the Hellenic arc/Florence Rise junction, and/or gravitational collapse of the overriding Anatolia Plate.

African Plate

Clockwise

Transtension

Slab

10.1093/gji/ggt323

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Citations (45)

Monitoring of Deformations Along Burdur Fethiye Fault Zone with GPS

Journal of Earthquake Engineering (2008)

Saffet Erdoğan Muhammed Şahin Hakan Yavaşoğlu İbrahim Tiryakioğlu Turan Erden

The Burdur Fethiye fault zone in southwestern Turkey is located in a tectonically active area. According to historical recordings, the region has been destroyed by earthquakes many times. In this region alone, more than 90 earthquakes with magnitudes of more than 5 have occurred since the beginning of the 20th century. Seven of them were recorded with magnitudes between 5.0 and 7.5 in the region between Burdur and Fethiye (October 3, 1914 Burdur: M 7.0, August 7, 1925 Dinar: M 6.0, May 12, 1971 Burdur: M 6.2, April 25, 1957 Fethiye: M 7.1, October 1, 1995 Dinar: M 6.1, December 15, 2000 Aksehir: M 5.9, February 3, 2002 Cay: M 6.0). To determine tectonic characteristics of the region, a network of ten sites was established and GPS measurements were made on this network. After the first year, the network was extended with six new points and additional GPS measurements were made with the financial support of TUBITAK (Scientific and Technical Research Council of Turkey). GPS data were processed using the GAMIT/GLOBK software package. After three years, GPS measurements were processed and tectonic movements of Burdur Fethiye fault zone were observed. Velocity values of tectonic movements, fault plane solutions and the geological structure of the zone show that the zone is active.

Seismic zone

Fault plane

10.1080/13632460802013784

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Citations (10)

A MODEL SUGGESTION FOR THE DETERMINATION OF THE TRAFFIC ACCIDENT HOTSPOTS ON THE TURKISH HIGHWAY ROAD NETWORK: A PILOT STUDY

Boletim de Ciências Geodésicas (2015)

Saffet Erdoğan Veli İlçi Ömer Soysal Aysegul Kormaz

Traffic accidents are very serious problems for human life and the environment. In road safety, it is crucial to identify the high risk locations to apply proper counter measures. This paper aims at introducing outcomes of a pilot project whose main goal is to develop a GIS based crash analysis system integrated with the quantitative methods for identification of high risk locations on road networks in Turkey. In this concept, traditional hotspot detection methods used in Turkey(crash frequency, rate, and severity) are compared with the spatial statistical methods including Moran's I, GetisOrd G and planar and network kernel density estimation in terms of their sensitivity to spatial characteristics of crash clusters. Many countries use traditional hotspot detection approaches such as crash frequency, crash rate, and crash severity as well as Turkey. In this project, we aimed at obtaining a model including different hotspot identification methods for the safety program of Turkey. In order to obtain the model, many hotspot detection methods will be used and compare stage by stage. In the first stage, the seven methods mentioned above are used and examined. Although some of these methods are compared in couple, there is no study using all these methods together extensively in the literature. Methods validated with a different spatial vantage points. Repetitiveness of hotspots in a seven years period are used to compare the methods. Meanwhile advantages and disadvantages of the methods according to location of hotspots are examined additionally. Results show that using planar KDE with Gi in the junction locations and using planar KDE with Moran's I in the straight road locations could improve the model while determining hotspots.

Hotspot (geology)

Kernel density estimation

10.1590/s1982-21702015000100011

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Citations (37)