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Specific features of NDVI, NDWI and MNDWI as reflected in land cover categories
194-202Views:946The remote sensing techniques provide a great possibility to analyze the environmental processes in local or global scale. Landsat images with their 30 m resolution are suitable among others for landcover mapping and change monitoring. In this study three spectral indices (NDVI, NDWI, MNDWI) were investigated from the aspect of land cover types: water body (W); plough land (PL); forest (F); vineyard (V); grassland (GL) and built-up areas (BU) using Landsat-7 ETM+ data. The range, the dissimilarities and the correlation of spectral indices were examined. In BU – GL – F categories similar NDVI values were calculated, but the other land cover types differed significantly. The water related indices (NDWI, MNDWI) were more effective (especially the MNDWI) to enhance water features, but the values of other categories ranged from narrower interval. Weak correlation were found among the indices due to the differences caused by the water land cover class. Statistically, most land cover types differed from each other, but in several cases similarities can be found when delineating vegetation with various water content. MNDWI was found as the most effective in highlighting water bodies.
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Spatial distribution of vegetation cover in Erbil city districts using high-resolution Pléiades satellite image
10-22Views:189Green spaces are playing an essential role for ecological balance and for human health in the city as well. They play a fundamental role in providing opportunities for relaxation and enjoying the beauty of nature for the urban population. Therefore, it is important to produce detailed vegetation maps to assist planners in designing strategies for the optimisation of urban ecosystem services and to provide a suitable plan for climate change adaptation in one fast growing city. Hence, this research is an investigation using 0.5 m high-resolution multispectral Pléiades data integrated with GIS data and techniques to detect and evaluate the spatial distribution of vegetation cover in Erbil City. A supervised classification was used to classify different land cover types, and a normalised difference vegetation index (NDVI) was used to retrieve it for the city districts. Moreover, to evaluate the accessibility of green space based on their distance and size, a buffer zone criterion was used. The results indicate that the built-up land coverage is 69% and vegetation land cover is 14%. Regarding NDVI results, the spatial distribution of vegetation cover was various and, in general, the lowest NDVI values were found in the districts located in the city centre. On the other hand, the spatial distribution of vegetation land cover regarding the city districts was non-equal and non-concentric. The newly built districts and the districts far from the Central Business District (CBD) recorded the lowest vegetation cover compared with the older constructed districts. Furthermore, most of the districts have a lack of access to green spaces based on their distance and size. Distance and accessibility of green areas throughout the city are not equally distributed. The majority of the city districts have access to green areas within radius buffer of two kilometres, whereas the lowest accessibility observed for those districts located in the northeast of the city in particular (Xanzad, Brayate, Setaqan and Raperin). Our study is one of the first investigations of decision-making support of the spatial planning in a fast-growing city in Iraq and will have a utilitarian impact on development processes and local and regional planning for Erbil City in the future.
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Population an land cover dinamics of Sundarbans impact zone is Bangladesh
1-13Views:205Sundarbans is the largest mangrove forest of the world that lies in Bangladesh and India. This paper examined the correlation among population dynamics of Sundarbans impact zone (SIZ) from 1974 to 2011; impact of climate change on the forest; and changes in land cover of the forest from 1973 to 2010. Population size of SIZ was increased by 1.6 times between 1974 and 2011, whereas decreased by 2% during 2001 to 2011. During 1973 to 2010, water bodies, barren land and vegetated land reduced by 7.35%, 49.56% and 15.92% respectively; while grass land increased by 228.14% during the same period. But both population size and vegetated land declined during 2001 and 2011. This was due to the landfall of two severe cyclones in 2007 and 2009 through Sundarbans which resulted thousands of human casualties and out migration, and destruction of the forest. In addition, anthropogenic interventions like low flow from Ganges River and policy constraints also contributed to the demolition of Sundarbans. Thus, population growth, climate change and anthropogenic interventions are playing a decisive role to the depletion of forest resources from the Sundarbans mangrove forest.
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Land use changes of the riparian landscape in Hungary between 1990 and 2018
82-95Views:108The protection and the restoration of rivers is one of the most important challenges of our time, due to the impact of human activities. The aim of the research was to assess the land use changes in the Hungarian riparian landscape. Several landscape corridors of different (50-100-300-500 m) widths near rivers were analyzed since 1990, using the CORINE Land Cover database. Positive changes in the land use of riparian landscape can be seen: continuous increase in the case of forest areas; and slight decrease in the extent of agricultural land since 1990. Unfortunately, the extent of grasslands and other near-natural areas is reduced; and there has been a steady increase in built-up areas. Examining the changes in built-up areas in more detail, a big increase is shown by the extent of urban green areas. As a continuation of the research, an evaluation methodology is being developed to determine the restoration potential of urban rivers on study area level and on national level. The results presented in this paper on land use changes and land use conditions can be useful for the research about restoration potential at national level.
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Time series analysis of major land resources using Landsat images in a part of district Jhansi, Uttar Pradesh, India
41-57Views:19Space born technology, with its repetitive nature, uses electromagnetic energy to capture digital data from the Earth's surface by remote sensing systems. The purpose of this research is to track changes in land resources with six time series (2003-09, 2003-15, 2003-21, 2009-15, 2009-21 and 2015-21) over a period of 18 years. Multi-date Landsat images of 2003, 2009, 2015 and 2021 have been used to monitor the changing pattern. Level – I classification scheme composed by NRSC/ ISRO and supervised Maximum Likelihood Classification (MLC) techniques were used to identify and classify land use/ land cover features located in Jhansi Tehsil. The findings show that there have been significant changes in land resources over the years. The area under agriculture land, built-up and waterbodies were increased by 48.83%, 53.53% and 106.73% while forest/ tree outside forest and wastelands were reduced by 59.74% and 38.68% respectively It is concluded that, the expansion of key land resources indicates the growth in population and socio-economic activities whereas the loss in some land resources might be due to human induced progressive activities.
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Transformation of land use pattern in the East Borsod coal basin from the beginning of minig industry to the political changes
223-231Views:200Historical geographic studies on land cover may support the understanding of the recent state. Focusing on coal mining, this process was followed and analyzed in the case of the East Borsod Coal Basin from the early 20th century to the political change. The contemporaneous maps and manuscripts concerning the mining were evaluated using geoinformatic techniques. Moreover, digitalized topographic map coming from the early and late period of mining (1924 and 1989, respectively) were analyzed. To determine the degree of human disturbance hemerobic relations and changes of the given land cover patches were quantified on the basis of the maps of the three military surveys, too. It can be stated that montanogenic subtype of an industrialagricultural landscape has been formed in the Bükkhát area. Beside the concentrated artificial surfaces, however, relative dominance of forest forming the matrix of the landscape remained.
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Land use change detection along the Pravara River basin in Maharashtra, using remote sensing and GIS techniques
71-86Views:62In the past few decades there has been an increasing pressure of population all over the world, especially in India, resulting in the utilization of every available patch of available land from woodlands to badlands. The study area represents a basin which is economically growing fast by converting the fallow lands, badlands and woodlands to agricultural land for the past few decades. IRS (Indian Remote sensing Satellites) 1 C – LISS III and IRS 1 C PAN and IRS P6 – LISS III and IRS 1 D PAN Images were merged to generate imageries with resolution matching to the landscape processes operating in the area. The images of the year 1997, 2000, 2004 and 2007 were analyzed to detect the changes in the landuse and landcover in the past ten years. The analysis reveals that there has been 20% increase in the agricultural area over the past ten years. Built up area also has increased from 1.35% to 6.36% of the area and dense vegetation also has marginally increased. The remarkable increase in the agricultural area occurs owing to the reclaim of the natural ravines and fallow lands. Presently the area looks promising, but it is necessary to understand the sedimentological and geomorphological characteristics of the area before massive invasion on any such landscapes because the benefit may be short lived.
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Comparative analysis of Landsat TM, ETM+, OLI and EO-1 ALI satellite images at the Tisza-tó area, Hungary
53-62Views:296Satellite images are important information sources of land cover analysis or land cover change monitoring. We used the sensors of four different spacecraft: TM, ETM+, OLI and ALI. We classified the study area using the Maximum Likelihood algorithm and used segmentation techniques for training area selection. We validated the results of all sensors to reveal which one produced the most accurate data. According to our study Landsat 8’s OLI performed the best (96.9%) followed by TM on Landsat 5 (96.2%) and ALI on EO-1 (94.8%) while Landsat 7’s ETM+ had the worst accuracy (86.3%).
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Analysis of the connection between urban land cover and census districts using geoinformatical methods
52-67Views:47Remote sensing resources are usually used in research to better understand urban built-up density, spatial structure and the processes of change. Based on results of image segmentation, landscape metrics indexes, texture and pattern may be analyzed beside the spatial changes in urban reflectance. Social processes within the settlement can be analyzed efficiently, although the census data may also be connected to the urban land cover data through geoinformation systems. On the research project different parameters of urban segments, i.e. patch number, mean patch area, total patch area, total patch perimeter, patch density and edge density, formations that make up the urban pattern were analyzed. Urban functional districts of different built-up density were separated using appropriate indexes, and extending the database with spectral content made it possible to review district boundaries and to mark new boundaries due to these changes.
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Studying floodplain roughness in an Upper Tisza study area
85-90Views:180Floods slowing down due to the significant decrease of the gradient have considerable sediment accumulation capacity in the floodplain. The grade of accumulation is further increased if the width of the floodplain is not uniform as water flowing out of the narrow sections diverge and its speed is decreased. Surface roughness in a study area of 492 hectares in the Upper Tisza region was analysed based on CIR (color-infrared) orthophotos from 2007. An NDVI index layer was created first on which object-based image segmentation and threshold-based image classification were performed. The study area is dominated by land cover / land use types (grassland-shrubs, forest) with high roughness values. It was concluded that vegetation activity based analyses on their own are not enough for determining floodplain roughness.
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Landscape change in Aizawl city: A geospatial approach to assess landscape indices and human-induced transformation
65-81Views:213The change in an area’s natural surroundings is called landscape change. This change may be gradual or accelerated depending on the factors that influence the change. Natural elements such as native animals and birds seldom bring about any modification to the environment. However, human-induced change is devastating and severely transforms the environment. Such environmental transformation can be evaluated with the land use/ land cover assessment through satellite imagery and calculation of landscape indices. This paper attempts to ascertain the direction and the nature of the human-induced change in the city of Aizawl. To this end, the city has been divided into four zones to enable inter-zone comparisons. A northeast and southwest direction of human landscape transformation has been ascertained with the help of GIS and remote sensing techniques and landscape indices in Aizawl city.
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Interferences between the ecological network and urbanized areas in Poland
65-77Views:27This paper presents spatial relations between Polish urban areas and valuable habitats and links between them composing the country’s ecological network. The quantitative analysis for 891 towns and cities was conducted using GIS techniques based on cartographic vector data and statistical data. Valuable habitats and links between them, such as national parks, landscape parks, CORINE biotopes sites, wildlife corridors linking NATURA 2000 sites and ECONET areas, can be found in 72% of Polish towns and cities. The proportion of artificial surfaces in those areas is different depending on the size of a town or city and its location. Urban areas with the highest index of presence of valuable habitats and links between them are concentrated in the south of Poland, where settlement network is most dense. However, in the case of those areas the proportion of artificial surfaces interfering with the ecological network is lower than Poland’s average, being 16%. The pressure of anthropogenic land cover extending onto the country’s ecological network is most conspicuous in urban areas with a population of at least several dozen thousand residents where the average developed area is 20.8% of their total area. The danger for the continuity of the nature system is best seen in the north western Poland, where artificial surfaces interference in towns and cities is largest. The analysis performed identified 82 towns and cities, in which the preservation of the continuity of the ecological network should be a priority in spatial management because of a higher than average index of the presence of valuable habitats and links between them and large proportion of artificial surfaces in those areas.
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Land cover analysis based on descriptive statistics of Sentinel-2 time series data
1-9Views:337In our paper we examined the opportunities of a classification based on descriptive statistics of NDVI throughout a year’s time series dataset. We used NDVI layers derived from cloud-free Sentinel-2 images in 2018. The NDVI layers were processed by object-based image analysis and classified into 5 classes, in accordance with Corine Land Cover (CLC) nomenclature. The result of classification had a 76.2% overall accuracy. We described the reasons for the disagreement in case of the most remarkable errors.
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Landslide Susceptibility mapping using the Analytical Hierarchy Process and GIS for Idukki District, Kerala, India
11-32Views:49This study demonstrates the application of the analytical hierarchy process (AHP) technique for landslide susceptibility mapping of Udumbanchola and Devikulam taluk of Idukki district (Kerala, India). The landslide conditioning factors, such as lithology, geomorphology, slope angle, slope aspect, relative relief, drainage properties, land use/ land cover, and lineament characteristics,are derived using remote sensing data and GIS. The landslide susceptibility of the region is estimated using the weights derived by the AHP method. The analysis indicates the controls exerted by the structural and fluvial process and relief characteristics on the landslide activity of the region. The landslide susceptibility map of the region suggests that the high and severe susceptible zones cover about 10.68% of the area, and another 9.40% falls under the moderate susceptibility zone. The results highlight the significance of implementing various structural and non-structural measures in the moderate to severe susceptibility zones to mitigate the impacts of landslides.
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Vegetation changes of Sundarbans based on Landsat imagery analysis between 1975 and 2006
1-9Views:322The Sundarbans in Bangladesh and India is the largest single block of tidal halophytic mangrove forest in the world. This forest is threatened by effect of climate change and manmade activities. The aim of this paper is to show changes in vegetation cover of Sundarbans since 1975 using Landsat imagery. Normalized Difference Vegetation Index is applied to quantify and qualify density of vegetation on a patch of land. Estimated land area (excluded water body) of this forest is 66% in Bangladesh, and 34% in India, respectively. Net erosion since 1975 to 2006 is ~5.9%. In vicinity of human settlement, areal changes are not observed since 1975. The mangrove forest is decreased by 19.3% due severe tropical cyclone in 1977 and 1988. Moreover, the dense forest is damaged by about 50%. However, more than 25 years is taken by Sundarbans to recover from damage by a severe tropical cyclone. The biodiversity of Sundarbans depends to fresh water flow through it. Therefore, the future of Sundarbans depends to the impact of climate change which has further effect to increasing intensity and frequency of severe tropical cyclone and salinity in water channels in Sundarbans.
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Evaluation of the possibilities for stream restoration: preassessment of the Váli-stream (Hungary)
26-44Views:224The purpose of this study is to evaluate the potential of restoration of a stream section. The starting point of the multiple-step assessment process was a historical analysis, which resulted in the definition of different sections within the study area, providing a base for the further restoration goals. The assessment of the current conditions was elaborated particularly to determine those factors, which could limit restoration. These assessments cover the land use pattern, furthermore the analysis of vegetation and habitat patches. As a result of the historical analysis, it has been found that the stream side habitat patches have decreased significantly despite the constant space available. This change was not caused by the increased area of the settlement, but rather by the higher dominancy of arable forms of land use. The greatest share of wet and mesic meadows and agricultural habitats in the study areas, covering 57.5% of the total area, indicates significant anthropogenic effects. Consequently it can be stated that the reference conditions are not the only determining factors of the restoration possibilities. Restoration style and intensity have been defined on basis of all assessed factors.
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A historic geographic approach to the anthropic disturbance in the Bükk region
58-65Views:288This paper introduce a historical geographical study on the process of land cover transformation in the Bükk Region, which can be regarded as a two-faced area concerning its anthropogenic disturbance. Based on historic mapping that began as early as the late 18th century, a database was produced, and the data was interpreted in the context of economic and social processes that took place in the area. Results could be presented in maps using the so-called Anthropogenic Disturbance Index (ADI). These maps demonstrate the peculiar land use pattern in the Bükk Region, namely co-habitation of the significantly transformed margins and the natural or quasi-natural central part. Between them, there are linear areas of intermediate disturbance. These areas, however, due to the foundation and activity of the Bükk National Park and modification of their economic value after the change of the political system, have not increased during the last several decades; rather a re-naturalization of the landscape is aimed.
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Boundless settlements – tendencies and future of urban sprawl in the agglomeration of Budapest
75-88Views:183The Budapest agglomeration is a rapidly changing environment. Urban sprawl has been a prominent process in municipalities around the Hungarian capital, and its pace has significantly increased since the change of regimes. In our paper, we analyse the tendencies of urban development, the role of territorial protection and the types of land use mostly threatened by urban sprawl in two study areas within the Budapest agglomeration. A significant part of the Northern study area – located on Szentendre Island – is under territorial protection, while the Southern study area – located on Csepel Island – has a considerably lower amount of protected areas. We found that the settlements of the Northern study area have been expanding at a much slower pace than their Southern counterparts, where in the absence of effective restrictions, extensive areas – mostly former agricultural fields – have been converted into built-up areas. In addition, the Spatial Plan of the agglomeration allows the same tendencies to continue in both areas in the future as well.