Geospatial technology for land cover analysis

International audienceThe Izmir region in Turkey is extremely valuable for the environment while being used immensely for tourism, agriculture and recreation. The geographic area of western Turkey is known for its unique physical and environmental settings. Due to its location in the Mediterranean climate, the region has certain typical features and is influenced by the local and regional climatic setting. The geography of the region combines diverse landforms, various geomorphological features, natural landscapes, species and vegetation richness: mountainous and hilly landscapes, caves, islands in the coastal area and lakes. The geology of the area of Western Anatolia is characterized by the neotectonic active faulting and high seismicity, which leads to the geomorphic instabilities and landslide formation in the research area. The vegetation in the study area is dominated by typical Mediterranean flora. The current environmental situation within the terrestrial parts of the ecosystems has been well discussed in several works. The main issues concerning deforestation of precious forest communities are desertification, soils erosion and land degradation in the surroundings. Karaburun Peninsula is an important part of Aegean Sea ecosystems and is well known in Turkey as one of the major undisturbed sites in western Turkey with precious biodiversity structure, aesthetic landscapes and unique environment. To maintain sustainable development of the Turkish nature, the unique landscapes should be protected for the sustainable coexistence of man and nature. Other sources of environmental threats are radioactive wastes and radionuclides that originate both from natural sources, for instance leaching from minerals, and from pollutant sources, mostly from nuclear power plants, explosions and accidents. These factors of ecological contamination have direct impact on the terrestrial ecosystems. The classification of Landsat TM imagery for the same study area taken at different years allowed the recording of gradual land degradation. The last one is mainly caused by intensive construction of the second house summer cottages, and tourist activities. Recent changes in land use / land cover types in selected regions of Turkey have been proved usingl land use change detection using measurements of carbon that indirectly indicate the extent of peatlands within the landscapes. The use of the Landsat TM images was applied to assess changes in the land cover types over time. The thematic mapping of the land cover types in the selected area has been done using methods of supervised classification. The legend representing land cover classes include a variety of land types that exist in the Izmir surroundings. After determining the land cover characteristics, separating images into diverse homogeneous areas, a compilation of the following land cover type parameters was done: Urban areas: residential and built-up regions, roads; 2) Croplands-1 (wheat); 3) Croplands-2 (barley and other cereals); 4) Agricultural lands (e.g. cotton); 5) Pastures; 6) Grassland; 7) Shrubland; 8) Broadleaf forest; 9) Evergreen needleleaf forest, pine (Pinus brutia, P.nigra, P.pinea, P.silvestris); 10) Evergreen coniferous forests, firs (Abies); 11) Mixed forests; 12) Wetlands; 13) Sparsely vegetated areas; 14) Water bodies (natural and artificial lakes, rivers); 15) CoppiceTraining sites were digitised as areas of known land cover type identity. The creation of training polygons was performed using manual digitising available in 'Drawing' function of Erdas Imagine, by specifying the corner points of each polygon. The attributive characteristics on the areas were entered using appropriate columns with 'land cover types'. In such a way, specific training areas were identified for each, from the 15 land use classes. The land cover classes were identified as sets of pixels that best represent each land type and region according to their spectral characteristics and topological information: location, neighborhood, type and size of the polygons