International Journal of Environment and Geoinformatics

108-113

Authors: Yavuz KARSAVRAN , Tarkan ERDİK , Zeynep Özge TERZİOĞLU

The Bosphorus Strait is the meeting point of Black Sea and Marmara Sea. It is under influence of many hydrological, oceanographical and meteorological variables. Clearly, it is known that River Danube discharge reaches to Bosphorus Strait. The approximate distance between outlet of River Danube and northern end of Bosphorus Strait are nearly 500km. In this study, the influence of the peak river Danube discharges (higher than 11000 m3/s) on Bosphorus Strait is investigated by using dataset of TAISEI Corporation, ISKI, Turkish State Meteorological Service and GRDC. To this end, the time series of water temperature, water salinity, and water level of the northern Bosphorus Strait is examined together with time series of River Danube discharge between 1st Oct 2004 and 31st Sept 2005. The validation is performed by checking wind speed, air pressure and precipitation data on Bosphorus Strait during that time. In addition, the power spectra of River Danube is calculated and compared with the other datasets as water level, surface layer water salinity and finally, surface water temperature data at the northern end of Bopshorus Strait.

120-126

Authors: Rafiu JİMOH , Yusuf O. AFONJA , Solihu O. OLAOSEGBA , Benjamin I. AJİSAFE , Latifat O. OYELAKİN

Geospatial data has been applied for positioning structural height restriction around the proposed MKO Abiola international Airport in Ido-Osun, Osun State. The study aimed at using geovisualisation method for guiding structural height restriction around the airport. In Nigeria, there is a growing demand for Airports and safety is paramount to aviation industry as calamity is irreversible. In respect of this, precautionary measures are better emplaced at inception to safeguard the industry as much as possible. For example, failure because of engine faults in flight cannot be completely erased, at least, planes hitting buildings due to either low altitude of the airplane or excessive height of structures could be totally abated. Data used for this study involved Geospatially acquired data obtained through primary and secondary methods. The data were processed and a 2km buffer zone was created around the proposed airport for analysis. Modelling of the study was done to relatively decipher the height relationship between the airport runway and the buffer zone. Hypotenuse theorem was used and available data, airplane altitude along various directions were calculated in relation to the mean sea level through which proposed heights restrictions were made for structures within the buffer zone in the study area. It was scientifically deduced that using of only number of building ,floors and other structures, the height above earth surface are not enough to set such height restriction, instead, elevations of adjoining land should also be a striking factor taken into set structural height restriction aided by Geo observation data.

132-139

Authors: Hasan TONBUL , Taskin KAVZOGLU

Very high-resolution images obtained with recently launched satellite sensors have been used intensively in the remote sensing area. The widespread use of high-resolution images has greatly facilitated the creation and updating of land use/land cover (LULC) maps. Traditional pixel-based image analysis methods that extract information based solely on the spectral values of pixels are generally not suitable for high-resolution images. Unlike pixel-based approaches, object-based image analysis (OBIA) uses pixel clustering (image objects) instead of pixels by considering the shape, texture, context and spectral features and provide richer information extraction. Image segmentation is an important process and prerequisite for the OBIA process. It is essential to evaluate the performance of segmentation algorithms for the determination of effective segmentation methods and optimization of segmentation parameters. In this study, the multi-resolution segmentation algorithm is used for the segmentation process. The effect of spectral bands on segmentation quality was analysed using a Worldview-2 high-resolution satellite image. In order to analyze segmentation quality, two unsupervised quality metrics, namely, F-measure and Plateau Objective Function (POF) values were calculated for each band separately. In this manner, optimum parameter values were determined using different variations of Moran's I Index and variance values. Image segmentation was performed by using different scale, shape and compactness parameter values. In this context, 30 segmentation analysis was performed considering three different spectral bands (red, green and near-infrared bands). The results showed that the highest segmentation quality was acquired for the NIR band among the spectral bands for the F-measure method, while the highest segmentation quality value was achieved for the green band for the POF metric. In addition, the optimum segmentation parameter values of the scale, shape and compactness were determined as 30-0.3-0.5 and 50-0.1-0.3 for F-measure and POF approaches, respectively.

147-156

Authors: Mamadou TRAORE , Tolga ÇAN , Senem TEKİN

Kayseri and Adana region of Taurus mountain belt is considered in the second range for iron mineralization in Turkey. The region is characterized by high-grade iron οre deposits under exploitation, development and exploration stage. The objective of this research is to assess the potential of Landsat-8 OLI and Advanced Spacebοrne Thermal Emissiοn and Reflectiοn Radiοmeter (Aster) data for mapping iron oxide zones hosted by carbonate units in low vegetation cover in Tufanbeyli (Adana) and surrounding region. The methods used in this study for the detection of the iron oxides are Band Ratio (BR) and Feature-Oriented Principal Cοmpοnent Selectiοn (FOPCS). The obtained results have good correlation with 92% confidence intervals in BR method for Ferric iron (2/1), ferric oxide (4/3) and ferrous iron (5/4 +1/2) of Aster and iron oxide (4/2) and ferrous iron (6/5) οf the Landsat-8. We note that the results obtained in this study using PC4 of FOPCS depict an excellent spatial correlation by comparison with the previously mapped iron deposits. We conclude that the Landsat-8 OLI and Aster images present good precision for iron ore discrimination in low vegetation lands.

165-171

Authors: Fulya GÖNÜLTAŞ , Muhammed Enes ATİK , Zaide DURAN

Solar energy is a renewable energy source directly from sunlight and its production depends on roof characteristics such as roof type and size. In solar potential analysis, the main purpose is to determine the suitable roofs for the placement of solar panels. Hence, roof plane detection plays a crucial role in solar energy assessment. In this study, a detailed comparison was presented between aerial photogrammetry data and LIDAR data for roof plane recognition applying RANSAC (Random Sample Consensus) algorithm. RANSAC algorithm was performed to 3D-point clouds obtained by both LIDAR (Laser Ranging and Detection) and aerial photogrammetric survey. In this regard, solar energy assessment from the results can be applied. It is shown that, the RANSAC algorithm detects building roofs better on the point cloud data acquired from airborne LIDAR regarding completeness within model, since aerial photogrammetric survey provides noisy data in spite of its high-density data. This noise in the source data leads to deformations in roof plane detection. The study area of the project is the campus of Istanbul Technical University. Accuracy information of the roof extraction of three different buildings are presented in tables.

184-190

Authors: Amara Ethel UZOR-TOTTY , Charles Uwadiae OYEGUN

Soil and water are the two main natural resources that sustain human existence on earth. Proper monitoring and maintenance of these resources are done on basin level. The IRB drains an area of 7,951.03 km2. The basin has a mean annual discharge of 120m3/sec and generates significant surface runoff and sediment. The study aim was to evaluate the sediment yield across IRB using the Soil and Water Assessment Tool (SWAT) model. SWAT is a watershed-based, semi-distributed hydrologic model for simulating hydrological processes at different spatial scales. The model utilized digital elevation model DEM to extract the river network, basin delineation, and sub-basin division. The sub-basins were further divided into hydrological response unit HRU at a threshold of 5% slope, 5% the land use and 5% soil. Harmonized soil data and two land-use data of 1995 and 2010 were used to simulate the sediment yield across IRB. The study result shows an increase in sediment yield of 0.73 t/ha from1995 to 2010. Sub-basin 10 has the highest sediment yield during the two periods; September and October are the months with the highest sediment yield.

205-212

Authors: Kadir Can KÜÇÜK , Berk ANBAROĞLU

The aim of this paper is to assess the spatial accuracy of OpenStreetMap (OSM) with respect to the Turkey Topographic Vector Database (TOPOVT) within the context of ‘building’ layer. Being an open-platform, anyone can access to OSM and add geographic entities as well as update them. Since there is no stringent standards, spatial accuracy assessment of OSM is an open research area. TOPOVT, on the other hand, is produced by the General Directorate of Mapping by following a standard procedure, where the maps are produced for 1:25000 scale or larger scale. Updating this database is a costly process and could only be conducted at specific time intervals. Therefore, automatic detection of the locations requiring update in TOPOVT would be an effective operation, which would eventually reduce the overall cost of the database update. However, the spatial accuracy of the geographical features have to be analysed in order to support such a motivation. Therefore, the aim of this paper is to assess the spatial accuracy of ‘building’ layer by calculating the Hausdorff distance between the matching (homologous) polygons in OSM and TOPOVT. The proposed methodology consists of two methods to detect the matching polygons: ‘overlap method’ and ‘centroid method’. Hausdorff distance is calculated for only those intersecting buildings in both of the layers. Since it is safe to assume that the intersecting polygons refer to the same geographic object, the calculated distance could be used to indicate the spatial accuracy of the building. The developed software is tested on an urban and a rural environment in Ankara, Turkey. The results indicate that the quality of OSM could well match with TOPOVT. Specifically, the average Hausdorff distance is approximately the same for both of the methods: approximately 9.5 metres. Considering that OSM and TOPOVT are generated through completely different processes’, the spatial accuracy is considered to be ‘good’ and ‘useful’ for many practical and operational purposes. In order to increase the effectiveness of the developed methodology in a real-life context, the whole process is integrated into an ArcMap extension and the code is made available on GitHub.