Document Type : Article extracted From phd dissertation
PhD Student in Geography and Urban Planning, Science and Research Branch, Islamic Azad University, Tehran, Iran
Professor of Geography and Urban Planning, Science and Research Branch, Islamic Azad University, Tehran, Iran
The rapid increase of population has changed the spatial patterns of urban areas in a complex way and has led to the spread of rural and urban sprawl in the surrounding areas. In the meantime, knowing how this growth and physical development of cities is of great value, to be used in planning future or even intra-contextual expansion, Therefore, the purpose of this study is to evaluate the urban sprawl and land use changes of Tehran metropolitan areas in different periods and land use change relative to each other. The research method is descriptive and analytical and the data collection tool is documentary and library studies and referring to relevant organizations and research centers on the subject under study.
The research method in this research is applied in terms of purpose. For analysis, Landsat satellite of Tehran metropolitan area was prepared for the period of 1352, 1364, 1379 and 1397. It should be noted that the prepared images are related to Landsat satellite (8.5.4) and TM and OLI / TIRS sensors, which are in the form of false color images related to the selected band 7, 4, 2. Then, the status of the intended uses for doing the specific work, which includes four classified classes, which are: constructed lands, vegetation lands, barren lands and water areas. Then, to measure and evaluate the status of land uses and classify satellite images, the Fuzzy ARTMAP model, which is a supervised algorithm, was used. Then, through the Lcm model, the made changes between land uses are displayed, and in the final stage of the model. CA-Markov has been used to predict changes of the land uses of Tehran metropolis until 1410.
Results and discussion
The highest increase in land use is in built lands. These lands have increased from 3000 hectares (9% of the total area) to 17569 hectares in 1397 (53% of the total area) in 1353, and in other uses, vegetation lands, barren lands and water areas have the highest decrease, respectively. In the following, it has been pointed out that each change of land use has changed the use of vegetation lands, barren lands and irrigated areas in favor of lands built in 1397. It can also be said that the barren lands and water areas were reduced in 1353 and increased to vegetation lands, and the vegetation lands and water areas were reduced and turned into barren lands, and the lands that were barren and vegetated. In favor of irrigated areas have changed land use. According to the analysis, it should be noted that the largest decrease in vegetation land from 64 to 97 was 5300 hectares
In the following, we can refer to the transfers between land uses, such as vegetation, barren and irrigated lands changes in favor of built lands, and some of the barren lands have been turned into vegetation lands, then from cover lands. Vegetation and irrigated areas have decreased and the area of barren lands has increased and finally barren lands have rarely changed their use to irrigated areas. As a result, it can be said that the urban sprawl expansion in the coming years has caused an imbalance in the lands of the region, which will have destructive effects.
The results of land use prediction by using of Markov chains and automated cells show that the constructed lands will increase to about 63% of the total area. Also, barren lands will decrease to 13%, vegetation lands to 24% and finally, water areas to less than 0.1%. As a result, the trend of possible changes in vegetation lands on the horizon of 1410 has led to formal and informal construction in and around the city.
The results of data analysis indicate that the change of natural land-use to constructed land uses has a growing trend, so that these lands in 1353 increased from 9% to 54% in 1397 and according to the forecast in the year in 1410, built-up land accounted for 62% of the total area, which indicates the severity of the environmental crisis. Also, barren land use with 71% and vegetation with 28% had the largest decrease in land use and the highest percentage change in useful lands of Tehran (irrigated lands and vegetation lands), and other lands with slower negative growth than these two land uses are changing, which indicates the severity of future environmental crises.