Evaluating Trend of Physical Urban Expansion of Shiraz City and physiographic conditions effect on land use changes

Natural environment hasn’t permanently adjusted with urban expansion and human settlements. Many historical cities have been abandoned due to these Natural environment incompatibilities. The most effective factors of natural environment on urban expansion are topography، slope، weather، geology، hydrology and geomorphology conditions. By increasing of trend urbanization، cities need to vast territories for settling the population، these territories have composed of different topographic and geomorphologic units. The impact of growth rate of city size on topographic and geomorphologic units will be complicated، by increasing of urban expansion. Orientation of physical expansion in terms of effective factors must be in a way that less damages imposes on natural environment and can be preserved environment in a direction of preservation of sustainable Development. Changes in the earth’s surface can be related to natural dynamics or human activities and can occur either suddenly or gradually. Accelerated urban growth is usually associated with and driven by the population concentration in an area. The extent of urbanization or its growth drives the change in land use/cover pattern. Land use and land cover changes may have adverse impacts on ecology of the area، specially hydro-geomorphology and vegetation. As the characteristics of land cover have important impacts on climate، biogeochemistry، hydrology and species diversity، land cover change has been indicated as one of the high priority concerns for research and for the development of strategies for sustainable management. Although urban areas currently cover only 3% of the Earth’s land surface، they have marked effects on environmental conditions at both local and global scales، including climate change. Recently، remote sensing has been used in combination with Geographical Information Systems (GIS) and Global Positioning Systems to assess land cover change more effectively than by remote sensing data only. This paper presents an integrated study of land use/cover changes and urban expansion in Shiraz city، Fars province in Iran. The study explores the temporal and spatial characteristics of urban expansion and land use/cover changes from 1990 to 2009. Statistical classification approaches have been used for the classification of the remotely sensed images obtained from various sensors viz. Landsat TM، ETM+ and IRS PAN، LISS-III. Land use/land cover changes (LUCC) are major cause of ecological environmental changes. Geometric correction was performed on all the images. At least 17 ground control points (GCPs) were used to register the images UTM zone 39. GCPs were dispersed throughout the scene، yielding a RMS error was around 0. 2 pixels. Geospatial data including municipal boundaries، road networks، geomorphic units and elevation units (DEM) were used to produce GIS layers by ArcGIS 9. 3. The most useful band combinations in Landsat for discrimination of land cover categories are bands 4-5-3، 4-3-2، and 3-2-1 assign ed as red، green، and blue، respectively. All satellite data were studied using spectral and spatial profiles to ascertain the digital numbers (DNs) of different LULC categories prior to classification. Finally، classification has been done using the Knowledge Classifier Module of ERDAS. Finally classification، five land cover categories exist in this area: (a) urban or built-up land; (b) agriculture; (c) water، (d) orchard، and (e) bare land. Results indicate that cropland، water، and orchard areas reduced by 37. 8%، 5. 8%and 45. 7% continuously over the past 19 years، while built-up area increased by 37%، respectively. The built-up area increased at the cost of decreased cropland، water and orchard. Lastly، the major factors influencing urban expansion and land use/cover change are also discussed. In general، the population، traffic conditions، industrialization، and policy are the major factors that influenced the urban expansion.