Manuchehr Farajzadeh; Mohsen Ahadnejad; Hadi Targholizadeh
Abstract
Extended Abstract
Introduction
Due to the large dimensions of earthquake damages and losses, more rapid procedures are required to identify damaged buildings. Field studies and old procedures are no longer efficient enough because of being time consuming, costly and requiring lots of workforce. ...
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Extended Abstract
Introduction
Due to the large dimensions of earthquake damages and losses, more rapid procedures are required to identify damaged buildings. Field studies and old procedures are no longer efficient enough because of being time consuming, costly and requiring lots of workforce. This research seeks to identify the buildings damaged by earthquakes through analyzing the spectral response of urban houses to the reflective bands and effective factors, before and after the earthquake, for recognizing buildings damaged in the earthquake and compare the results of the reflective bands with each other, and then, determine the most efficient band among them. The earthquake stricken city of Bam was selected as the case study of this research. In order to identify the damaged urban houses, satellite imagery and remote sensing reflective bands were considered for detecting the changes, distinguishing the bands, and analyzing the spectral reflection profile.
Materials and Methods
The high resolution Quick bird satellite, photographed the city of Bam just eight days after the earthquake on January 3, 2004. The satellite also had taken a clear image of Bam about three months before the earthquake on September 30, 2003, that, with regard to the objectives of the research and the capabilities of the images taken, these Quick Bird satellite images were selected to study and investigate in this field. The method of this research is to analyze the spectral reflection profile and the factors affecting it. Since the multi-spectral remote sensing is a set of reflective, emissive or backscattering energy from the study area in electromagnetic multi-spectral bands, the aim of this research is to describe why terrestrial phenomena show different responses to the electromagnetic spectrum, and to analyze their spectral curve as well. To this end, we established an analytical strategy to achieve a better interpretation of the blue (band 1: 450 - 520 nm), green (band 2: 520 - 600 nm), red (band 3: 630 - 690 nm), and infrared (band 4: 760 - 900 nm) reflective bands. And the earthquake stricken city of Bam was selected as the case study of this research in order to identify the damaged urban houses by analyzing the spectral reflection profile and factors affecting it.
Results and Discussion
Urban housing is composed of various materials (concrete, asphalt, metal, plastic and soil) by man in various ways for building houses. When earthquake strikes, these houses might be destroyed. Therefore, satellite multi-temporal images before and after the earthquake were selected as data for analyzing the electromagnetic spectrum curve of the study area. In this research, the vulnerability of urban houses is different from one place to another. Therefore, educational samples of the case study from different parts of the city such as those which have been completely destroyed, partially destroyed or have remained intact, were selected. Then, the spectral response analysis of the urban houses was carried out in 4 blue (band 1: 450 - 520 nm) green (band 2: 520 - 600 nm) red (band 3: 630 - 690 nm) and Infrared (band 4: 760 - 900 nm) reflective bands before and after the earthquake in order to identify effective factors and the bands independent of these factors comparing with other bands. The results show that, before the earthquake occurs, some factors such as shadows cause a sharp decrease in the reflection in all bands, the atmospheric scattering at short wavelengths with increasing spectral reflection, the angle of sunshine, type of material, the surface smoothness or roughness of the surface, the time of the day, the height and texture had a great impact on the 3 blue, green and red reflective bands. Infrared band with a rectangular shape in spectral curve is a band independent of the aforementioned factors (with the exception of the shadow and surface smoothness of the materials).
Conclusion
The results obtained from analyzing the spectral response of the urban houses in four reflective bands (Blue, Green, Red and Infrared) indicated that in general, the urban houses had high reflection and shadows had less reflection before the earthquake. After the earthquake, urban houses showed an irregular and significant reduction in spectral reflection, and the spectral reflection curve was irregular as well. However, the method of analyzing the spectral reflection profile is a point estimation method and does not result in a map, and this method is often used to check the accuracy of other methods.
Mohsen Ahadnejadroshti; Ashraf Azimzadeh Irany; Saeed Najafy
Abstract
Abstract
physical growth and development of border cities with regard to defense and security structures, migration and population movements, communication and transportation infrastructure, urban management, sources of livelihood, diversity of cultural customs and…, have undergone changes and ...
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Abstract
physical growth and development of border cities with regard to defense and security structures, migration and population movements, communication and transportation infrastructure, urban management, sources of livelihood, diversity of cultural customs and…, have undergone changes and developments under the influence of internal and external communication over the years. The main objective of this research is to compare adaptively the physical development of Eastern and Western border cities of the country with a case study of Zabol and Piranshahr cities. For this purpose, ETM, TIRS, and OLI sensor images of Landsat satellites 5, 7, and 8 were selected for the period of 1986-2015 (1365-1394), and Holdren models and Shannon Entropy were used. After geo-referencing the images, Fuzzy method has been used to classify the changes of development, and the urban expansion was foreseen for the year 2030 (1409) using the combination method of Markov chains and automated cells. The results show that during the 29 years of study, the lands constructed in Zabol city has reached from 2578.10 hectares in 1986 (1365) to 3419.92 hectares in 2015 (1394), and in the city of Piranshahr from 612.10 hectares in 1986 to 1785.90 hectares in 2015. During this period, the greatest land use changes in Zabol were observed in agricultural lands with 58.76 % and the least changes were in gardens with 0.42 %. In the city of Piranshahr, however, the highest rate of land use changes were observed in agricultural lands with 67.88% and the least changes in wastelands with 2.16%. According to the entropy model, it has been shown that in the last 29 years, the physical expansion of cities has been growing sporadically and non-densely. But the rate of shapelessness has decreased in the city of Piranshahr compared to the year of 1986. Between the years of 1986 and 2015, about 85% of physical growth in Zabol city was related to population growth and 15% of the city growth was related to the horizontal and spiral growth of the city, while in the city of Piranshahr, all the city's physical growth has resulted from the population growth during the aforementioned years due to the negative gross per capita. Considering the projected population during these 15 years, it is expected that 364.4 ha in the city of Zabol and 15.94 ha in the city of Piranshahr will be added to the urban constructed lands. The adaptive comparison of the cities with regard to the population growth has led to an uneven development of the cities, which requires the guidance, growth and development of the cities with appropriate and desirable plans.
Sayyed Ahmad Hosseini; Eisa Ebrahimzadeh; Mojtaba Rafieian; Mahdi Modiri; Mohsen Ahadnejad Roshti
Abstract
Monitoring the expansion of urban areas on a macro scale is very important for planning urban development and prevention of catastrophic problems in metropolitan areas. However, in most cases, lack of basic information in this area, especially in developing countries, is one of the main obstacles to ...
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Monitoring the expansion of urban areas on a macro scale is very important for planning urban development and prevention of catastrophic problems in metropolitan areas. However, in most cases, lack of basic information in this area, especially in developing countries, is one of the main obstacles to achieve this. Therefore, in order to investigate the balance in the urban system of Iran, the urban primacy index and the Rank-Sizedistribution of the cities in Iran were utilized from 1335 to 1390 using population data of urban areas in different census periods. Also, in order to monitor the dynamics of urbanization in contemporary Iran from the spatial-temporal view, the DMSP / OLS multi-temporal images of the years 1371 to 1391 were used.Considering all the indices in the urban system of Iran, the results of the research showed that the urbanprimacy phenomenon has existed in all these periods, and in general, the results derived from the Rank-size logarithmic distribution ofthe cities of Iranbetween the years of 1335 and 1390 indicate that inthe last 55 years, the distribution of the cities has tended towards imbalance over time, and indicate the most unbalanced distribution with an absolute slope of 1.142 in the year of 1385. Finally, the linear regression model was used to analyze the DMSP images in relation to urban areas and the gross national product (GDP).The results showed that there was a linear relationship between light at night and population, urban population and the GDP. The R2 value for the urban population is equal to 0.854 which shows that these images can be used as a factor for identifying the dynamics of the urban system in Iran.
