Measuring the spatial impacts of urbanization on the surface water resource basins in Istanbul via remote sensing

Istanbul is one of the largest metropolitan cities in the World. The city has experienced rapid industrialization and urbanization in the second half of the twentieth century. Between 1950 and 2000, the city has grown by an average of 4.5% annually. Given the scale of the growth, neither local nor the central governments have shown capability of controlling the influx of migration, most of which settled illegally on public lands. Most of the settlements lack the basic sewerage facilities, and a significant portion of which are on the major water resource basins. As of today, Istanbul Metropolitan Municipality (IMM) not only has to cope with the infrastructure problems, but also has to find ways of solving the problem of illegal occupations of public lands and water resource basins. This paper presents the land use changes in the water resource basins providing water to the Istanbul Metropolitan Area. Using four consecutive Landsat images between 1990 and 2005, the changes in 12 different land use categories are obtained via overlay operations by GIS for water resource basins surrounding the City of Istanbul. It has been observed that the most critical land use changes are in the nearest basins to the city. The capability of Landsat and IKONOS images in determining the alterations in the macro form of the city are also discussed. Finally, possibility of utilization of new technologies in policy making regarding environmental management in Istanbul is discussed.     

Monitoring urban expansion and land use/land cover changes of Shanghai metropolitan area during the transitional economy (1979�C2009) in China

This study explored the spatio-temporal dynamics and evolution of land use/cover changes and urban expansion in Shanghai metropolitan area, China, during the transitional economy period (1979?C2009) using multi-temporal satellite images and geographic information systems (GIS). A maximum likelihood supervised classification algorithm was employed to extract information from four landsat images, with the post-classification change detection technique and GIS-based spatial analysis methods used to detect land-use and land-cover (LULC) changes. The overall Kappa indices of land use/cover change maps ranged from 0.79 to 0.89. Results indicated that urbanization has accelerated at an unprecedented scale and rate during the study period, leading to a considerable reduction in the area of farmland and green land. Findings further revealed that water bodies and bare land increased, obviously due to large-scale coastal development after 2000. The direction of urban expansion was along a north-south axis from 1979 to 2000, but after 2000 this growth changed to spread from both the existing urban area and along transport routes in all directions. Urban expansion and subsequent LULC changes in Shanghai have largely been driven by policy reform, population growth, and economic development. Rapid urban expansion through clearing of vegetation has led to a wide range of eco-environmental degradation.     

Land cover changes on the coastal zone of Candarli Bay, Turkey using remotely sensed data

Land cover of the Earth is changing dramatically because of human activities. Information about changes is useful for management of natural resources. Rapid land cover changes have taken place in many coastal areas of Turkey over the last two decades due to urbanization and land degradation. In this paper, land cover change dynamics were investigated by the combined use of satellite remote sensing and geographical information systems. The main objective of the study was to determine land-cover transition rates among land cover types in coastal areas of Turkey. A time series of Landsat TM and ASTER images were used to gather land cover change data of the coastal line of Candarli Bay, Izmir, Turkey. The images were classified using supervised classification and a post-classification comparison approach was used in change detection. The results show significant increase in urban areas but decrease in semi natural and agricultural areas.     

Impacts of urban growth on forest cover in Istanbul (1987–2007)

This article reports findings of a study that examined the impacts of urban growth on forest cover in Istanbul between 1987 and 2007. Four Landsat images from 1987, 1990, 2000, and 2007 were classified with maximum likelihood supervised classification method by using ERDAS IMAGINE 9.1. Forest and urban areas were given highest importance in the classification, while other land-use characteristics, like agriculture and bare soil, were grouped into a third class as others. The study revealed that rapid increase in population and accompanying unplanned urban growth in Istanbul resulted in significant changes in land use after 1987. Urban areas have expanded 87.9% from 1987 to 2007, while forest areas declined 5.4% in the same period. One of the most significant results of the study was that total forest areas in Istanbul have increased 0.3% between 2000 and 2007. This suggests that progress has been made in Istanbul not only in having sustainable urban growth, but also in preserving, restoring, and even expanding forest areas, especially after the year 2000.     

Using landsat data to determine land use/land cover changes in Samsun, Turkey

The rapid industrialization and urbanization of an area require quick preparation of actual land use/land cover (LU/LC) maps in order to detect and avoid overuse and damage of the landscape beyond sustainable development limits. Remote sensing technology fits well for long-term monitoring and assessment of such effects. The aim of this study was to analyze LU/LC changes between 1980 and 1999 in Samsun, Turkey, using satellite images. Three Landsat images from 1980, 1987 and 1999 were used to determine changes. A post classification technique was used based on a hybrid classification approach (unsupervised and supervised). Images were classified into six LU/LC types; urban, agriculture, dense forest, open forest-hazelnut, barren land and water area. It is found that significant changes in land cover occurred over the study period. The results showed an increase in urban, open forest/hazelnut, barren land and water area and a decrease in agriculture and dense forest in between 1980 and 1999. In this period, urban land increased from 0.77% to 2.47% of the total area, primarily due to conversions from agricultural land and forest to a lesser degree. While the area of dense forest decreased from 41.09% to 29.64% of the total area, the area of open forest and hazelnut increased from 6.73% to 11.88%.     

Land-cover changes in an urban lake watershed in a mega-city, Central China

Urbanization can exert a profound influence on land covers and landscape characteristics. In this study, we characterize the impact of urbanization on land cover and lacustrine landscape and their consequences in a large urban lake watershed, Donghu Lake watershed (the largest urban lake in China), Central China, by using Landsat TM satellite images of three periods of 1987, 1993 and 1999 and ground-based information. We grouped the land covers into six categories: water body, vegetable land, forested land, shrub-grass land, open area and urban land, and calculated patch-related landscape indices to analyze the effects of urbanization on landscape features. We overlaid the land cover maps of the three periods to track the land cover change processes. The results indicated that urban land continuously expanded from 9.1% of the total watershed area in 1987, to 19.4% in 1993, and to 29.6% in 1999. The vegetable land increased from 7.0% in 1987, 11.9% in 1993, to 13.9% in 1999 to sustain the demands of vegetable for increased urban population. Concurrently, continuous reduction of other land cover types occurred between 1987 and 1999: water body decreased from 30.4% to 23.8%, and forested land from 33.6% to 24.3%. We found that the expansion of urban land has at least in part caused a decrease in relatively wild habitats, such as urban forest and lake water area. These alterations had resulted in significant negative environmental consequences, including decline of lakes, deterioration of water and air quality, and loss of biodiversity.     

Remote sensing imageries for land cover and water quality dynamics on the west coast of Korea

As human activities influence land cover changes, the environment on human life such as water quality, has been impacted. In particular, huge constructions or reclamation projects are responsible for dramatic land cover changes. The Saemangeum area in South Korea has been one of the largest reclamation projects to progress nearly in two decades. In this study, Landsat-5 Thematic Mapper and Landsat-7 Enhanced Thematic Mapper Plus images were used to classify land cover types in the Saemangeum area. A change detection method was utilized to determine the impacts of the reclamation project. While wetland, grassland, and urban areas were increased, forest, water, and agricultural areas were decreased during the reclamation progress. Water quality analysis related to the land cover changes was conducted to determine the influence of reclamation construction on the environment. Chemical oxygen demand and suspended sediment variability were significantly impacted by the sea current changes after the dyke construction. On the contrary, water temperature and dissolved oxygen were affected by the seasonal influences rather than the reclamation construction. Total nitrogen and total phosphorus were influenced by the fertilizers and pesticides as a result of agricultural activity. The trends of suspended sediment from Landsat images were similar with those from the ground observation sites and also impacted by the dyke construction.     

Monitoring the changes in impervious surface ratio and urban heat island intensity between 1987 and 2011 in Szeged,Hungary

Landsat time series data make it possible to continuously map and examine urban land cover changes and effects on urban environments. The objectives of this study are (1) to map and analyse an impervious surface and its changes within a census district and (2) to monitor the effects of increasing impervious surface ratios on population and environment. We used satellite images from 1987, 2003 and 2011 to map the impervious surface ratio in the census district of Szeged, Hungary through normalized spectral mixture analysis. Significant increases were detected from 1987 to 2011 in industrial areas (5.7–9.1%) and inner residential areas (2.5–4.8%), whereas decreases were observed in the city centre and housing estates due to vegetation growth. Urban heat island (UHI) values were derived from the impervious surface fraction map to analyse the impact of urban land cover changes. In 2011, the average value in the industrial area was 1.76 °C, whereas that in the inner residential area was 1.35–1.69 °C. In the city centre zones and housing estates, values ranging from 1.4 to 1.5 °C and from 1.29 to 1.5 °C, respectively, were observed. Our study reveals that long-term land cover changes can be derived at the district level from Landsat images and that their effects can be identified and analysed, providing important information for city planners and policy makers.     

Monitoring land use/land cover changes using CORINE land cover data: a case study of Silivri coastal zone in Metropolitan Istanbul

The objective of the present study was to assess changes in land use/land cover patterns in the coastal town of Silivri, a part of greater Istanbul administratively. In the assessment, remotely sensed data, in the form of satellite images, and geographic information systems were used. Types of land use/land cover were designated as the percentage of the total area studied. Results calculated from the satellite data for land cover classification were compared successfully with the database Coordination of Information on the Environment (CORINE). This served as a reference to appraise the reliability of the study presented here. The CORINE Program was established by the European Commission to create a harmonized Geographical Information System on the state of the environment in the European Community. Unplanned urbanization is causing land use changes mainly in developing countries such as Turkey. This situation in Turkey is frequently observed in the city of Istanbul. There are only a few studies of land use–land cover changes which provide an integrated assessment of the biophysical and societal causes and consequences of environmental degradation in Istanbul. The research area comprised greater Silivri Town which is situated by the coast of Marmara Sea, and it is located approximately 60 km west of Istanbul. The city of Istanbul is one of the largest metropolises in Europe with ca. 15 million inhabitants. Additionally, greater Silivri is located near the terminal point of the state highway connecting Istanbul with Europe. Measuring of changes occurring in land use would help control future planning of settlements; hence, it is of importance for the Gretaer Silivri and Silivri Town. Following our evaluations, coastal zone of Silivri was classified into the land use groups of artificial surfaces agricultural areas and forests and seminatural areas with 47.1%, 12.66%, and 22.62%, respectively.     

The response of hydrophobic organics and potential toxicity in streams to urbanization of watersheds in six metropolitan areas of the United States

Semipermeable membrane devices (SPMDs) were deployed in streams along a gradient of urban land-use intensity in and around six metropolitan areas: Atlanta, Georgia; Raleigh-Durham, North Carolina; and Denver-Fort Collins, Colorado, in 2003; and Dallas-Fort Worth, Texas; Milwaukee-Green Bay, Wisconsin; and Portland, Oregon, in 2004 to examine relations between percent urban land cover in watersheds and the occurrence, concentrations, and potential toxicity of hydrophobic compounds. Of the 142 endpoints measured in SPMD dialysates, 30 were significantly (alpha = 0.05) related to the percent of urban land cover in the watersheds in at least one metropolitan area. These 30 endpoints included the aggregated measures of the total number of compounds detected and relative toxicity (Microtox(R) and P450RGS assays), in addition to the concentrations of 27 individual hydrophobic compounds. The number of compounds detected, P450RGS assay values, and the concentrations of pyrogenic polycyclic aromatic hydrocarbons (PAHs) were significantly related to percent urban land cover in all six metropolitan areas. Pentachloroanisole, the most frequently detected compound, was significantly related to urban land cover in all metropolitan areas except Dallas-Fort Worth. Petrogenic PAHs and dibenzofurans were positively related to percent urban land cover in Atlanta, Raleigh-Durham, Denver, and Milwaukee-Green Bay. Results for other endpoints were much more variable. The number of endpoints significantly related to urban land cover ranged from 6 in Portland to 21 Raleigh-Durham. Based on differences in the number and suite of endpoints related to urban intensity, these results provide evidence of differences in factors governing source strength, transport, and/or fate of hydrophobic compounds in the six metropolitan areas studied. The most consistent and significant results were that bioavailable, aryl hydrocarbon receptor agonists increase in streams as basins become urbanized. Potential toxicity mediated by this metabolic pathway is indicated as an important factor in the response of aquatic biota to urbanization.     

Detecting the spatial differentiation in settlement change rates during rapid urbanization in the Nanjing metropolitan region, China

Urbanization produced significant landscape changes throughout the world. China has been experiencing accelerated urbanization during the past decades. Rapid land use/land over conversion occurred nationwide in urbanization, manifesting noteworthy characteristics of landscape dynamics. In this study, we investigated the spatial differentiation in settlement change rates among 1-km² land units in the Nanjing metropolitan region, a representative rapidly urbanizing region in China. Remotely sensed detection using Landsat TM data of 1988–2006 showed that settlement increase, termed as positive growth (PG), was predominant in the study area; while settlement decrease, termed as negative growth (NG), also had a considerable proportion, which was mainly attributed to the increase of green lands and the shrink of rural settlements. Along the urban-rural gradient, PG and NG showed similar mono-peaked patterns. The urban fringe zone with a consistent width of about 4 km was identified as the hot zone of both PG and NG over the three unequal periods. For both PG and NG, high-rated changes tended to exhibit more aggregative patterns along the gradient in the urban fringe zone. Settlement changes showed apparent anisotropy across directions. The directional distribution of PG was significantly negatively correlated to the topographic variables, suggesting that the mountains constrained urban expansion in an “area-weighted inverse-distance power” form. Significant correlation between PG and NG in a time-lagged manner showed the “increase–decrease” fluctuation occurred in settlement changes, reflecting the “urban expansion–land reconfiguration” process in rapid urbanization in Nanjing.     

Determining the impact of urban components on land surface temperature of Istanbul by using remote sensing indices

For the past 60 years, Istanbul has been experiencing an accelerated urban expansion. This urban expansion is leading to the replacement of natural surfaces by various artificial materials. This situation has a critical impact on the environment due to the alteration of heat energy balance. In this study, the effect upon the urban heat island (UHI) of Istanbul was analyzed using 2009 dated Landsat 5 Thematic Mapper (TM) data. An Index Based Built-up Index (IBI) was used to derive artificial surfaces in the study area. To produce the IBI index, Soil-Adjusted Vegetation Index, Normalized Difference Built-up Index, and Modified Normalized Difference Water Index were calculated. Land surface temperature (LST) distribution was derived from Landsat 5 TM images using a mono-window algorithm. In addition, 24 transects were selected, and different regression models were applied to explore the correlation between LST and IBI index. The results show that artificial surfaces have a positive exponential relationship with LST rather than a simple linear one. An ecological evaluation index of the region was calculated to explore the impact of both the vegetated land and the artificial surfaces on the UHI. Therefore, the quantitative relationship of urban components (artificial surfaces, vegetation, and water) and LST was examined using multivariate statistical analysis, and the correlation coefficient was obtained as 0.829. This suggested that the areas with a high rate of urbanization will accelerate the rise of LST and UHI in Istanbul.     

Land use patterns and urbanization in the holy city of Varanasi, India: a scenario

Rapid urbanization and increasing land use changes due to population and economic growth in selected landscapes is being witnessed of late in India and other developing countries. The cities are expanding in all directions resulting in large-scale urban sprawl and changes in urban land use. The spatial pattern of such changes is clearly noticed on the urban fringes or city peripheral rural areas than in the city center. In fact, this is reflected in changing urban land use patterns. There is an urgent need to accurately describe land use changes for planning and sustainable management. In the recent times, remote sensing is gaining importance as vital tool in the analysis and integration of spatial data. This study intends to estimate land use pattern in a planned and unplanned urban setup and also to analyze the impact of change in land use pattern in the Varanasi urban environment. The results indicate that the planned urban setup had a higher tree cover to that of unplanned area in the Varanasi City, although a considerable disparity existed within the planned urban setups. The results emphasize the need to critically review concepts of urban planning and give more consideration to the preservation and management of urban tree cover/greenspace.     

Analysing urban expansion and land use suitability for the city of Kahramanmaraş, Turkey, and its surrounding region

This study aimed at quantifying changes in urban area of the city of Kahramanmara? (K.Mara?) between 1948 and 2006, and analysing suitability of existing land use (LU) to the land potential. Urban change information was derived from two black-white monoscopic aerial photographs, and IKONOS and the QuickBird images acquired in 1948, 1985, 2000 and 2006, respectively. QuickBird image and soil map with 1:25,000 scale were used to analyze suitability of the current LU pattern to the land potential. The findings showed that the urban area of K.Mara? has expanded approximately 13 times during the past six decades. According to current LU and the soil map, productive and moderately productive soils were largely (73.2%) allocated for agricultural activities, which means that there was a strong consistency between the agricultural LU type and the land capability. However, widespread agriculture on the non-productive soils, and urbanization on the fertile agricultural lands were assessed as unsuitable from sustainable LU viewpoint. Considering this phenomenon, it is possible to say that rapid urban expansion has a growing pressure on the fertile agricultural soils. Monitoring LU changes, particularly urbanization, and developing effective LU plans based on the land capability were determined as the most important approaches to encourage sustainable use of land.     

Estimation of late twentieth century land-cover change in California

We present the first comprehensive multi-temporal analysis of land-cover change for California across its major ecological regions and primary land-cover types. Recently completed satellite-based estimates of land-cover and land-use change information for large portions of the United States allow for consistent measurement and comparison across heterogeneous landscapes. Landsat data were employed within a pure-panel stratified one-stage cluster sample to estimate and characterize land-cover change for 1973?C2000. Results indicate anthropogenic and natural disturbances, such as forest cutting and fire, were the dominant changes, followed by large fluctuations between agriculture and rangelands. Contrary to common perception, agriculture remained relatively stable over the 27-year period with an estimated loss of 1.0% of agricultural land. The largest net declines occurred in the grasslands/shrubs class at 5,131 km² and forest class at 4,722 km². Developed lands increased by 37.6%, composing an estimated 4.2% of the state??s land cover by 2000.     

平顶山地区景观格局动态特征及驱动力分析

以平顶山地区为研究对象,利用平顶山地区1992年Landsat-TM影像和2006年中巴资源卫星遥感影像,运用景观生态学原理,借助遥感和GIS技术,选取景观多样性、景观优势度、景观均匀度、景观破碎度等指标指数进行分析,揭示平顶山地区近14 a来城市景观格局演变及其驱动力。研究结果表明:交通用地、工矿及居民点和耕地用地显著增加,林地、水域显著减少;除工矿及居民点外,该地区各类型斑块数量均有增加,其中林地增加最为显著;交通用地、工矿及居民点的破碎度降低,水域、林地、耕地的景观类型破碎度增高;耕地的分维数、形状指数呈下降趋势,而林地的分维数和形状指数呈上升趋势;平顶山地区景观多样性和均匀度都呈下降趋势,而优势度和破碎度增加;景观格局变化受人为因素影响较大,人口增加、经济发展、城镇化和工业发展是平顶山地区景观格局演变的主要驱动力。     

Remote sensing and GIS-based integrated analysis of land cover change in Duzce plain and its surroundings (north western Turkey)

The aim of this study is to research natural land cover change caused by the permanent effects of human activities in Duzce plain and its surroundings, and to determine the current status of the land cover. For this purpose, two Landsat TM images were used in the study for the years 1987 and 2010. These images are analysed by using data image processing techniques in ERDAS Imagine©10.0 and ArcGIS©10.0 software. Land cover change nomenclature is classified according to the Coordination of Information on the Environment Level 2 Classification (1—urban fabric, 2—industrial, commercial and transport units, 3—heterogeneous agricultural areas, 4—forests, and 5—inland wetlands). Furthermore, the image analysis results are confirmed by the field research. According to the results, a decrease of 33.5 % was recorded in forest areas from 24,840.7 to 16,529.0 ha; an increase of 11.2 % was recorded in heterogeneous agricultural areas from 47,702.7 to 53,051.7 ha. Natural vegetation, which is the large part of land cover in the research area, has been changing rapidly because of rapid urbanisation and agricultural activities. As a result, it is concluded that significant changes have occurred on the natural land cover between the years 1987 and 2010 in the Duzce plain and its surroundings.     

Environmental modelling of Omerli catchment area in Istanbul, Turkey using remote sensing and GIS techniques

Omerli Reservoir is one of the major drinking water reservoirs of Greater Metropolis Istanbul, providing 40% of the overall water demand. Istanbul where is one of the greatest metropolitan areas of the world with a population over 10 million and a rate of population increase about twice that of Turkey. As a result of population growth and industrial development, Omerli watershed is highly affected by the wastewater discharges from the residential areas and industrial plants. The main objective of this study is to investigate the temporal assessment of the land-use/cover of the Omerli Watershed and the water quality changes in the Reservoir. It is not possible to adequately control urbanization and other pollution sources affecting the water quality. Responses of these detrimental effects are due to rapidly increasing population, unplanned and illegal housing, and irrelevant industries at the protection zones of the watershed, together with insufficient infrastructure. The study is focused on the assessment of urbanization in relation to land use and water quality using Remote Sensing (RS) and Geographic Information Systems (GIS) techniques for all the four protection zones of the Reservoir and a time variant analyzing model is obtained. IRS-1C LISS and IRS-1C PAN, LANDSAT-5 TM satellite data of 1997, 1998, 2000, 2001 and 2006 are analyzed by confirmation through the ground truth data. RS data have been transferred into UTM coordinate system and image enhancement and classification techniques were used. Raster data were converted to vector data that belongs to study area to analyze in GIS for the purpose of planning and decision-making on protected watersheds.     

Analyzing riparian forest cover changes along the Firniz River in the Mediterranean City of Kahramanmaras in Turkey

Riparian forests adjacent to surface water are important transitional zones which maintain and enrich biodiversity and ensure the sustainability in a forest ecosystem. Also, riparian forests maintain water quality, reduce sediment delivery, enhance habitat areas for aquatic life and wildlife, and provide ecological corridors between the upland and the downstream. However, the riparian ecosystems have been degraded mainly due to human development, forest operations, and agricultural activities. In order to evaluate the impacts of these factors on riparian forests, it is necessary to estimate trends in forest cover changes. This study aims to analyze riparian forest cover changes along the Firniz River located in Mediterranean city of Kahramanmaras in Turkey. Changes in riparian forest cover from 1989 to 2010 have been determined by implementing supervised classification method on a series of Landsat TM imagery of the study area. The results indicated that the classification process applied on 1989 and 2010 images provided overall accuracy of 80.08 and 75 %, respectively. It was found that the most common land use class within the riparian zone was productive forest, followed by degraded forest, agricultural areas, and other land use classes. The results also indicated that the areas of degraded forest and forest openings increased, while productive forest and agricultural areas decreased between the years of 1989 and 2010. The amount of agricultural areas decreased due to the reduction in the population of rural people. According to these results, it can be concluded that special forest management and operation techniques should be implemented to restore the forest ecosystem in riparian areas.     

Land use and land cover (LULC) of the Republic of the Maldives: first national map and LULC change analysis using remote-sensing data

The Maldives islands in recent decades have experienced dramatic land-use change. Uninhabited islands were turned into new resort islands; evergreen tropical forests were cut, to be replaced by fields and new built-up areas. All these changes happened without a proper monitoring and urban planning strategy from the Maldivian government due to the lack of national land-use and land-cover (LULC) data. This study aimed to realize the first land-use map of the entire Maldives archipelago and to detect land-use and land-cover change (LULCC) using high-resolution satellite images and socioeconomic data. Due to the peculiar geographic and environmental features of the archipelago, the land-use map was obtained by visual interpretation and manual digitization of land-use patches. The images used, dated 2011, were obtained from Digital Globe’s WorldView 1 and WorldView 2 satellites. Nine land-use classes and 18 subclasses were identified and mapped. During a field survey, ground control points were collected to test the geographic and thematic accuracy of the land-use map. The final product’s overall accuracy was 85%. Once the accuracy of the map had been checked, LULCC maps were created using images from the early 2000s derived from Google Earth historical imagery. Post-classification comparison of the classified maps showed that growth of built-up and agricultural areas resulted in decreases in forest land and shrubland. The LULCC maps also revealed an increase in land reclamation inside lagoons near inhabited islands, resulting in environmental impacts on fragile reef habitat. The LULC map of the Republic of the Maldives produced in this study can be used by government authorities to make sustainable land-use planning decisions and to provide better management of land use and land cover.