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Urban dynamics and urban sprawl in hill stations of India: a case study of Shillong city
1-10Views:364The hill stations of India are remnants of colonial past built by the British where the scenic landscape and climate similar to Britain attracted the British to set up cantonments and sanatoriums for the British troops and their families. Shillong City whose origin dates back to the 19th century, was the British capital of Assam Province, the administrative seat of undivided Assam after India’s Independence and at present the capital of Meghalaya. The city’s growth resulted from the continuous influx of population to fulfil the changing socio-economic and political dynamics of the city. This hill station was built by the British with a vision to house a population of less than one lakh. It was then a cluster of a few scattered hamlets, which at present has grown tremendously with 12 contiguous urban units forming the Shillong Urban Agglomeration (SUA). With the help of RS -GIS using Shannon entropy technique as a landscape metric, the urban sprawl of Shillong has been measured from the year 1991 to 2001.The rapid growth has led to an urban sprawl which poses various challenges to the city’s environment.
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Urban vegetation classification with high-resolution PlanetScope and SkySat multispectral imagery
66-75Views:813In this study two high-resolution satellite imagery, the PlanetScope, and SkySat were compared based on their classification capabilities of urban vegetation. During the research, we applied Random Forest and Support Vector Machine classification methods at a study area, center of Rome, Italy. We performed the classifications based on the spectral bands, then we involved the NDVI index, too. We evaluated the classification performance of the classifiers using different sets of input data with ROC curves and AUC values. Additional statistical analyses were applied to reveal the correlation structure of the satellite bands and the NDVI and General Linear Modeling to evaluate the AUC of different models. Although different classification methods did not result in significantly differing outcomes (AUC values between 0.96 and 0.99), SVM’s performance was better. The contribution of NDVI resulted in significantly higher AUC values. SkySat’s bands provided slightly better input data related to PlanetScope but the difference was minimal (~3%); accordingly, both satellites ensured excellent classification results.
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Landscape shape index, as a potencial indicator of urban development in Hungary
78-88Views:541The study of settlement shape, morphology and structure is a classic topic of urban geography. Since the 1960s multiple shape indices have been developed. Urban patterns were then compared with geometric forms or, alternatively their temporal changes were tracked and analysed. In the current study we adapted the landscape shape index (LSI) to analyse the historical shape development of eight Hungarian cities. The LSI is capable to demonstrate the functional and mutual relationship between the developed area and their immediate physical and natural environment. Over the past 230 years the land area of the studied cities has increased manifold for several reasons: on average, an areal increase of 10.4 to 24.5 was observed for the eight settlements, while their perimeter increased by 8.8 to 30.3 times. Simultaneously with their size growth, the studied cities are characterized by an increasingly fragmented and dissected ground plans. Consequently, due to the longer border between the developed areas and the adjacent natural zones, urban areas have become increasingly sensitive to environmental effects over the past century, while mutual ecological and environmental interactions has also considerably increased between the adjoining zones. In general, cities of hilly and low-mountain areas had the highest LSIs, whereas cities located on relatively flat grounds had comparatively low LSIs. We also investigated the rank correlation of the historical change of LSI of the studied settlements. Cities of high positive correlations (> 0.9) were classified into two major categories. Miskolc, Pécs, Szeged and Kecskemét belonged to the group of higher LSIs, whereas Székesfehérvár and Nyíregyháza fell into the class of medium LSIs and the third category included Debrecen and Győr, cities of low (< 0.9) LSIs. Based on the temporal trends of the LSIs, our results provide applicable information for decision makers in order to monitor, manage and track their investments, city management policies and infrastructural development strategies.
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A remote sensing and GIS-based analysis on the impact of dam construction towards the land use land cover pattern of Bakreswar Watershed, India
25-42Views:172The present study evaluates the impact of the dam construction on land use and land cover (LULC) pattern of the Bakreswar Watershed in the Birbhum District, West Bengal, India during 1990-2020. Landsat 5 TM and Landsat 8 OLI data were used to analyze the LULC pattern during the pre- and post-dam construction periods. Supervised image classification using the maximum likelihood algorithm was done to generate LULC and change detection maps in ArcGIS. LULC dynamic attitude and transfer matrix were prepared based on the LULC maps of four years. The results show that the dam construction significantly influenced the LULC pattern of the region. The highest rate of increase is seen in waterbody (86.37%) during 1990–2000 due to dam construction. Cultivated land also increased by 12.31% during this period. After the dam construction, the conversion rate from fallow land to cultivated land is higher in the downstream area rather than the upstream area. The area under barren land decreased by 53.28% in 1990–2000 and by 41.23% during 2009–2020 due to its conversion to built-up area. The built-up area rapidly increased during the past 20 years, by 34.57% and 45% during 1990–2000 and 2009-2020, respectively. Major change is seen along the Panagarh–Morgram Highway which connects two urban centers, Suri and Dubrajpur. Settlement concentration is also high around the Bakreswar Thermal Power Plant (BkTPP) and BkTPP Township. This study provides a useful approach to understanding the impacts of dam construction on cultivated area change and how transportation facility influences urban agglomeration.
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Monitoring the changes of a suburban settlement by remote sensing
76-83Views:128Satellite images and aerial photos support settlement surveys and provide valuable information of their physical environment. Aerial photos are excellent tools to overview large areas and simultaneously provide high-resolution images making them efficient tools to monitor built-up areas and their surroundings. Aerial photos can also be used to collect complex spatial data as well as to detect various temporal changes on the land surface, such as construction of illegal edifices and waste dumps. The 10 to 30-meter resolution SPOT and Landsat images are usually insufficient for site specific data collection and analysis. However, the recently available 0.5-meter resolution satellite images have broadened the scope of monitoring and data collection projects. Beyond environmental and urban monitoring, the new available high-resolution satellite images simplify the everyday work of local authorities and will facilitate the development of governmental databases that include spatial information for public utilities and other communal facilities.