Use of ArcGIS Applications for Analysis and Representation of the Terrains: The Case Study of Alakır River Sub-basin

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1 Use of ArcGIS Applications for Analysis and Representation of the Terrains: The Case Study of Alakır River Sub-basin Ahmet BENLİAY, Tahsin YILMAZ and H. Ekin OKTAY 1 Introduction 3D visualizations have become increasingly important in the field of landscape architecture. They can be used on various scales from garden design to regional planning. More over these visualizations are necessarily used in the strategic planning or analysis of potential impacts arising from the proposed developments on existing landscapes. Therefore designers and planners should provide more realistic and comprehensive scenarios so that they can reach knowledge-based decisions more quickly. In this study, the success of analysis and representations for designs with ArcGIS 9.3 software has been tested in the case of Alakır River sub-basin in Antalya, Turkey. Landscape analysis has been done by ArcMap applications by building on the current land use data, DEM (Digital Elevation Model) and satellite images. Suitable areas for landscape design have been determined by the weighted overlay analysis in ArcMap. Presentations for the proposals and animations for the evaluation map have been created with ArcMap and ArcScene, respectively. 2 Material & Methods 2.1 Input Data The study area Alakır River sub-basin, which is approximately 30 km 2, is surrounded by Toçak Hill, Karanlıcakbaşı Hill, Çatalkatran Hill, Çatal Hill, Salurdağı Hill, Toptaş Hill and Alakır Dam in Kumluca, Antalya, Turkey. For the study, topographical and transport infrastructure data, which was produced from the aerial photos, was obtained from the Ministry of National Defence. The current land use data were obtained from General Directorate of Rural Services of Turkey as raster map. Map codes are P24-a2 and P24-a3, scales are 1/25 000, projections are Transverse Mercator and datums are ED-50/WGS84. For updating the data, some field observations were done and P178-coded Landsat satellite images (year 2001) were evaluated. For animations and 3D stereo views, Google Earth satellite images were used.

2 216 A. Benliay, T.Yılmaz and H.E. Oktay 2.2 Modelling approach The Map model for analyses and representation of the terrain is illustrated in Fig. 1. The model was built using two steps, landscape analysis and landscape design proposal presentations. Fig. 1: Map model of analysis and representation of the terrain. Three inputs (current land use data, digital elevation model and 3D stereo views) were evaluated for landscape analysis. All raster data maps and Google Earth images were rectified with precision for georeferencing. In the study area, there were four major land uses. Roads and river were in polyline, forest and open spaces were in polygon characteristics. Buffer analysis for roads and river were added for landscape analysis stage. Due to the complexity of the real terrain, an abstracted and simplified media needs to be used in order to make the landform workable. The most commonly accepted digital media is the Triangulated Irregular Network (TIN). A terrain model, which consists of surface information, can be visualized through a series of visual styles (LAMEIRAS ET AL. 2009). The rectified raster images used for creating shape file, which contains contour polylines with their elevation attributes and TIN, were created by the use of 3d analyst extensions. DEM, terrain model, hillshade, aspect and slope surface analysis were created. With ArcScene application, a topographic shape can catch heights from surface and create 3d map which can be viewed in different ways (orthogonal, perspective and stereo), using DEM (LAMMEREN ET AL. 2009). Hillshade map and satellite images, which elevation values were predicted by DEM, were used for creating stereo views for landscape analysis.

3 Use of the ArcGIS Applications for Analysis and Representation of the Terrains: The Case Study of Alakır River Sub-basin 217 Landscape design proposals were developed by the evaluation of landscape analysis maps. In this study, four design proposals (camping grounds, trekking paths, climbing paths and parking areas) were suggested. Weighted overlay combines several rasters using a common measurement scale and weights, each according to its importance (NAGARAJAN AND SINGH 2009; ESRI 2011). For weighted overlay analysis, all features were converted into rasters and all rasters were reclassified. Weighted overlay is a technique for applying a common measurement scale of values to diverse and dissimilar inputs to create an integrated analysis (LAMMEREN ET AL. 2009). Criteria, which were created for design proposals, were used as factor values in weighted overlay analysis and, with this analysis, suitable area maps for camping grounds and parking areas and path maps for trekking and climbing were created. Stereo views and animations which consist of Evaluation map, DEM and satellite images were created by the use of ArcScene application. Fly-through animation was created to demonstrate the proposals. 3 Results The results of analysis layouts are shown in Figure 2. In layouts, adding the hillshade analysis gave the effect of third dimension in plan. Terrain, aspect and slope analysis were presented with the hillshade effect, so that the form of the land could be seen. The analysis shows that terrain elevations change between 0 m and m and all aspects can be seen on terrain. Terrains that are in East and South aspects are in greater percentage than the rest. Slopes of the terrain vary greatly. From the analysis we can see that the slopes which are higher than 30 m are in high percentage. Fig. 2: Analysis maps of Alakır river sub-basin. The result maps of proposal layouts and scenes from animation are show in Figure 3. After the evaluation process, camping ground was emerged as 484 m 2 to the east of Toçak Hill. Trekking paths were emerged as three paths that connect to each other (11.2 km, 1.8 km and

4 218 A. Benliay, T.Yılmaz and H.E. Oktay 1.5 km in length, respectively). Climbing paths were emerged as five paths (3.9 km, 3.3 km, 1.4 km, 1.3 km and 1 km in length, respectively). Parking areas were emerged as three separated grounds which are 441 m 2, 251 m 2 and 73 m 2, respectively. Fig. 3: Maps for suitable areas and evaluation map animation of Alakır River sub-basin. 4 Conclusions & Outlook The presented work is an attempt to apply GIS tools for the design process of landscapes. ArcMap is a powerful tool for analysing terrains and suitable area decisions. Also, data can be created easily and powerful layouts can be created. Understanding the properties of terrains can be very important for designers. This can be given to a map by creating it with a three dimensional features. 3d layouts, animations and stereo views can act as an enhanced perception tools. In particular, 3d views and stereo images can not only be used as an analysing tool, but also as a checking tool for landscape design proposals. The relations between the terrain and design proposals can be judged. Also simulating future attributes of land use can enrich design process and designs can be more progressive. There is no doubt that more advanced interactive design tools will be developed soon. 5 References ESRI (2011): Weighted Overlay. arcgisdesktop/9.3/index.cfm? Lameiras, J. M., Jørgensen, I. and Marques, P.F., (2009): Digital Terrain Modelling in Landscape Architecture. DLA 2009 Conferance, May 2009, Malta

5 Use of the ArcGIS Applications for Analysis and Representation of the Terrains: The Case Study of Alakır River Sub-basin Lammeren R. V., Weitkamp G., Verhagen S., Ruijten J. (2009): Geo-visualization assignments GRS ArcGIS 9.3 (ArcMap & ArcScene) Manual. Nagarajan M., Sujit Singh S. (2009): Assessment of Groundwater Potential Zones using GIS Technique. J. Indian Soc. Remote Sens. (March) Thomson, J. A., Bell, J. C., Buttler C.A (2001): Digital Elevation Model Resolution Effects on Terrain Attribute Calculation and Quantitative Soil-Landscape Modeling. Geoderma 219