Study of Urban Sprawl and Its Impact on Vegetation, Land Surface Temperature and Air Pollution Using Remote Sensing and GIS in Kathmandu Valley from 2015 to 2020

The Kathmandu Valley has seen substantial urbanization over the past decades while being the nation’s economic centre. Built-up areas have expanded quickly along with the population, having a significantly negative influence on the environment. Recently, Kathmandu was named as the most polluted city in Asia. Urban sprawl has had a negative influence on Kathmandu’s residents in several ways. The state of urban sprawl and the effects it has had on the Kathmandu Valley have been examined using land sat imagery. In this study, IDW was used in GIS to analyze the pollution status using data of PM 2.5 and PM 10 obtained from various monitoring sites. A supervised classification was used to create a LULC map of Kathmandu for the years 2015, 2018, and 2020. To assess the state of the vegetation and determine whether the Kathmandu Valley is being affected by urban heat, NDVI and Land sat temperature calculations were also made. The study’s results were obtained using remote sensing and GIS technology. The built-up area in Kathmandu Valley has grown by 20% over the past five years, impacting land use patterns and deteriorating vegetation cover. Due to the rise of built-up area, which is a good heat absorber, the temperature in the Kathmandu Valley is rising along with the degradation of the vegetation cover. The pollution in the Kathmandu Valley is at its worst, and residents are compelled to breathe air that is significantly more polluted than the prescribed limit.

Measuring urban sprawl in Beijing with geo-spatial indices

Concerning about the rapid urban growth in recent China, this study takes Beijing as a case and puts forward that urban sprawl can be measured from spatial configuration, urban growth efficiency and external impacts, and then develops a geo-spatial indices system for measuring sprawl, a total of 13 indicators. In order to calculate these indices, different sources data are selected, including land use maps, former land use planning, land price and floor-area-ratio samples, digitized map of the highways and city centers, population and GDP statistical data, etc. Various GIS spatial analysis methods are used to spatialize these indices into 100mx100m cells. Besides, an integrated urban sprawl index is calculated by weight sum of these 13 indices. The application result indicates that geo-spatial indices system can capture most of the typical features and interior differentia of urban sprawl. Construction land in Beijing has kept fast growing with large amount, low efficiency and disordered spatial configuration, indicating a typical sprawling tendency. The following specific sprawl features are identified by each indicator： （1） typical spatial configuration of sprawling： obvious fragmentation and irregularity of landscape due to unsuccessful enforcement of land use planning, unadvisable pattern of typical discontinuous development, strip development and leapfrog development; （2） low efficiency of sprawl： low development density, low population density and economic output in newly developed area; and （3） negative impacts on agriculture, environment and city life. According to the integrated sprawl index, the sprawling amount in the northern part is larger than that in the southern, but the sprawling extent is in converse case; most sprawling area include the marginal area of the near suburbs and the area between highways, etc. Four sprawling patterns are identified： randomly expansion at urban fringe, strip development along or between highways, scattered development of industrial land, leapfrog development of urban residence and industrial area.

Quantification of Urban Sprawl for Past-To-Future in Abha City,Saudi Arabia

Given that many cities in Saudi Arabia have been observing rapid urbanization since the 1990s,scarce studies on the spatial pattern of urban expansion in Saudi Arabia have been conducted.Therefore,the present study investigates the evidence of land use and land cover(LULC)dynamics and urban sprawl in Abha City of Saudi Arabia,which has been experiencing rapid urbanization,from the past to the future using novel and sophisticated methods.The SVM classifier was used in this study to classify the LULC maps for 1990,2000,and 2018.The LULC dynamics between 1990–2000,2000–2018,and 1990–2018 have been analyzed using delta()change and the Markovian transitional probability matrix.Urban sprawl or urban expansion was modeled using two approaches,such as landscape fragmentation and presence frequency for the first time.The future LULC map for 2028 was predicted using the artificial neural network-cellular automata model(ANN-CA).Future LULC was analyzed using landscape fragmentation and frequency approaches.The results of LULC maps showed that urban areas increased by 334.4%between 1990 and 2018.The Delta change rate showed that 16.34%in urban areas has increased since 1990.While,the transitional probability matrix between 1990 and 2018 reported that the built-up area is the largest stable LULC,having an 83.6%transitional probability value.While 17.9%,21.8%,12.4%,and 10.5%of agricultural land,scrubland,exposed rocks,and water bodies were transformed into built-up areas.Urban sprawl models showed that 139 km^(2)of new urban areas had been set up in 2018,49 and 69 km^(2)in 1990 and 2000.Furthermore,in 2018,more than 200%of urban areas were stabilized or became core urban areas.The future LULC map(2028)showed that the built-up area would be 343.72 km^(2),followed by scrubland(342.98 km^(2))and sparse vegetation(89.96 km^(2)).The new urban area in 2028 would be 169 km^(2).The authorities and planners should focus more on the sustainable development of urban areas;otherwise,it would harm the natural and urban environment.

Urban Sprawl in Wadi Goss Watershed (Jeddah City/Western Saudi Arabia) and Its Impact on Vulnerability and Flood Hazards

Today, climate change imposes enormous challenges on a global scale. The interactions of the balances between the need for development, population growth, massive urbanization generate a negative impact on the presence of these climate changes. One of the direct consequences of these changes is the phenomenon of flash floods, a phenomenon that hit the city of Jeddah (city located in west of Saudi Arabia) twice, one in 2009 and the other in 2011, causing significant human and material damage. Floods are considered as a direct result of the combination of extreme weather and hydrological phenomena;in most cases, the magnitude of these floods is magnified by anthropogenic factors, which increases the risk. According to the risk triangle, risk is defined as a probabilistic function that depends on three essential elements: exposure, vulnerability and hazard. If any of these three elements undergo growth the risk also does so and vice versa. Exposure and vulnerability will depend on the presence of human activities in the study area. This study is conducted on the Wadi Goss watershed as it was one of the most violent basins during the 2009 and 2011 floods. Indeed, we present in this study the extent of the urban extension in the Wadi Goss watershed, since 1984 to days and this by the using Landsat images. Given the nature of the study area, we present a method based on the calculation of various indices followed by a classification operation in order to define the urbanized zones inside the Wadi Goss watershed and then estimate the urban sprawl inside the watershed. We also present in this paper, the characteristics of the watershed as well as the evolution of the urbanized areas exposed to the phenomenon of floods and their contribution to the changes of the hydrological behavior of the basin, and to increase the evolution of the risk of the floods. We have shown through this study that the urban footprint has increased from 90 hectares in 1985 to 850 hectares in 2015. This urban footprint represents 12% of the total area of the watershed. Most of the urban evolution was operated on the wadi area with a concentration in the western part of the basin and especially at its outlet.

Geospatial Assessment of the Impact of Urban Sprawl in Akure, Southwestern Nigeria

This study analyzed trend and examined the factors responsible for urban sprawl in Akure with a view to develop a user-friendly geospatial database for monitoring urban sprawl in the study area. Medium resolution satellite imageries derived from Landsat (TM) and (ETM+) comprising of four dates (1986, 1991, 2002 and 2011) were analyzed. The results revealed that built-up area increased rapidly by 43.31% from 5857.54 hectares in 1986 to 8394.21 hectares in 1991. It further increased by 72.02% from 8762.76 hectares to 15073.7 hectares in 2011. Field study conducted in 2013 involved in-depth interviews and questionnaires to stakeholders and residence respectively. The analysis showed that there was a weak negative relationship (r = -0.189, p < 0.01) between gender and “house ownership”, a weak positive relationship (r = 0.343, p < 0.01) between marital status and “house ownership” and a weak negative relationship (r = -0.159, p < 0.05) between “number of children” and “house ownership” in the sprawl location. Geo-spatial database modeled was tested by subjecting it to spatial analysis to show its capability to answer question pertaining to all the entities of the database. The study concluded that urban sprawl increased and if not reversed, might constitute greater social and environmental problems in the future.

Assessment of Urban Sprawl Using Geospatial Techniques in Awka Town, Anambra State, Nigeria

Cities and towns in developing countries are experiencing an unplanned and uncontrolled development known as urban sprawl. This research examines urban sprawl in Awka metropolis, between 1986 and 2016. Landsat 5 Thematic Mapper (TM) of 1986, Landsat Enhanced Thematic Mapper plus (ETM+) data of the year 2000 and Enhanced Thematic Mapper plus (ETM+) 2016 were used for this study. Geographic Information System was employed for the analysis of the data. Result showed that Awka metropolis witnessed a remarkable growth between 1986 and 2016 from mere 3444.48 Km2 in 1986 to about 11,452.46 Km2 in 2016. This growth contributed to the sharp decline in farmland from 25,500.51 km2 (19.13%) in 1986 to 17,848.44 km2 (13.60%) in 2000 and further declined to 10,037.07 km2 (10.01%) in 2016. Bare surfaces witnessed an increase over the years of this study. This increase is as a result of clearing of natural vegetation for urban development, thereby exposing the land to direct contact with rainfall, leading to gully erosion in the area. Light vegetation also witnessed a sharp decreased from (38.53%) in 1986 to (8.53%) in 2000. It further decreased (8.53%) to (4.62%) in 2016. Therefore, increase in population led to the increase in urban sprawl in the study area. The study recommends that there is a need for a regular monitoring of urban sprawl and development in the study area by the state government especially with the aid of geospatial techniques for better decision making.

The Use of GIS, Remote Sensing and Shannon’s Entropy Statistical Techniques to Analyze and Monitor the Spatial and Temporal Patterns of Urbanization and Sprawl in Zarqa City, Jordan

The aim of this study is to understand and quantify the urban growth and trend in Zarqa city during the period 1990 to 2014 and to produce land use and cover map for the studied area through the use of the GIS and remote sensing techniques with Shannon’s Entropy statistical method. For this purpose, three Landsat images were used for land use classification by using supervised maximum likelihood classification techniques to extract and assess the changes of urban lands. The results indicated that the urban areas in Zarqa city increased by 22.15% in the period from 1990 to 2005 and 14.86% from 2005 to 2014, with a rate of expansion of 0.96 and by 1.31 km2/ year for the two time periods respectively. The entropy value increased from 1.20 in the first period to 1.38 in the second, while the entropy value for the NE, NW, SE and SW zones showed high values, which confirmed that urban expansion and sprawling had existed in the past twenty four years in the study area. Urban expansion and sprawl cause different impacts on the natural, economic, and aesthetic aspects of the city which lead and guide government officials and planners to understand and monitor current growth and visualize future growth.

Understanding the Urban Sprawl in the Mid-Size Latin American Cities through the Urban Form:Analysis of the Concepcion Metropolitan Area(Chile)

Latin American cities, like those from North America and Europe, experience problems of urban sprawl. However, few studies have dedicated exclusively to this phenomenon in specific cities, and this omission is particularly noticeable regarding cities not considered among the megalopolis of the continent. The present work analyzes urban sprawl through an urban form in the Concepción Metropolitan Area, Chile, between 1990 and 2009, considering local aspects that may have played a role in the process. The main empirical results obtained from this study reveal a metropolitan area that has expanded intensely over a 20-year period, growing from 9000 hectares to more than 17,000 ha for a 96% increment in the built-up area. The new urban surfaces consolidate a central conurbation that strengthens the role of the main downtowns, with less-intense occupation towards the sub-centers but in a structure that follows the transportation infrastructure. Over the last 20 years, the distance between the shapes has grown progressively by around 2 km, increasing the size of the ellipse by more than 1000 km2. In particular the complexity of the urbanized surfaces has grown, becoming more irregular in shape and less compact as they come to occupy larger areas. So our principal findings include: an increment of nearly 100% in the urban surface, the importance of a polycentric urban structure in the process of consolidation as a support for analyzing different spatial dynamics, and the growing morphological irregularity of the territory of the sprawl.

Impact of regional human capital and urban sprawl on forest——based on a forest conservation model

Metropolitan cities in China have become a major economic hubs with an unprecedented increase of land use and decline of environmental resources. Based on a simple and abstract forest conservation model, this paper attempts to explain changes of forest resources caused by urban sprawl. Through the research, it is found that high level of regional human capital is beneficial to curb urban sprawl. In this vein the model presents the urban forest conservation cost strategy at the Nash equilibrium of varied discount factor and parameter control.

Modeling and Mapping of Urban Sprawl Pattern in Cairo Using Multi-Temporal Landsat Images, and Shannon’s Entropy

Cairo city, being the Egypt’s industrial and cultural center, has a problem of rapid urban sprawl. The city has an extremely high population density which is continuously increasing through informal settlements that grow by sprawling due to migration from the Nile Delta villages and the high population growth rates. The present study attempts to understand, detect and quantify the spatial pattern of Cairo’s urban sprawl using Shannon’s entropy and multi-temporal Landsat TM and ETM images acquired for the period from 1984 to 2013. Supervised classification was applied to extract the built-up areas and to measure the changes in the urban land-use class among the city wards. Shannon’s entropy was applied to model the city’s urban sprawl, trend and spatial change. The entropy values for the city’s electoral wards were modeled and used in an interpolation function to create an entropy surface (index) for each acquired temporal image. Such index indicates the spatial pattern of the urban sprawl and provides a visual comparison of the entropy phenomenon in such wards. Results indicate that Shannon’s entropy index increased from (1.4615) in year 1984 to (2.1023) in year 2013, indicating more dispersed urban growth, a sign of urban sprawl. The maximum entropy values are found in the eastern wards namely El Nozha, Awal Nasr District, Thany Nasr-District, El Salam, El Marg and El Bassatein. A regression analysis was carried for the population growth rate and the built-up areas. Findings help in understanding the sprawl patterns and dynamics among Cairo’s electoral wards and provide a visual comparison. The applied methodology provides explanations and facilitates tracing and measuring the urban sprawl which is needed by decision makers and city planners of mega cities.

Enhanced Urban Sprawl Monitoring over the Entire District of Rome through Joint Analysis of ALOS AVNIR-2 and SENTINEL-2A Data

Based on the continuation of our past study, the present analysis is conducted to examine recent effects of the urbanization process occurring over the entire district of Rome. Overlays of ALOS AVNIR-2 and SENTINEL-2A satellite images, collected over a 6 years period, were validated via Geographic Information System (GIS) techniques, in a particular procedure applied to urban land and agricultural transformations. The use of Copernicus SENTINEL-2A imagery has improved the previous results on urban processes, by reducing the uncertainty of the discrimination of land cover classes and facilitating the photo-interpretation. Statistical analysis was performed via the Urban Area Profile index in order to quantify the sprawl phenomenon, by defining several landscape metrics. This work, to be enriched in the future by means of complementary information available from Copernicus radar sensors, like the one onboard Sentinel-1, completes the series of observations on land use published by the Italian National Institute for Environmental Protection and Research, which stopped back in 2008.

Upshot of Sprawl Incidence on Pattern of Land Use Changes and Building Physiognomies in Akure Region, Nigeria

This study investigates the upshot of sprawl incidence on pattern of land use changes and building physiognomies in Akure and its environs.Using social survey research method(SSRM)to investigate the upshot,data were gathered via structured questionnaires on selected households in the region,involving Akure municipal and eight contiguous communities.Basically,the survey method involves interview,personal observation and photo-snaps to elucidate existing situation in the region.Average households’population in Akure municipal was estimated at 95,232 while 14,794 was estimated in the selected eight contiguous communities.From this,a sample of 1%was systematically selected,which amounted to 1100 sampled households.Findings show regular massive inflow of people into the city due to unguided expansions that have serious sway on land use determinant in the city and its contiguous communities.It also has significant influence on variation in building arrangements and facility distribution across the region.To mitigate this,the study advocates proactive efforts of stakeholders in urban management to employing inventive measures over private and public lands in logical manners.It also suggests the espousal of regional development programs to checkmate the rate of peoples’incursion into Akure,being the state capital.Local government headquarters and other major towns in the region should be reinforced with functional basic facilities to curtail the excessive influx into the city.

Urban Sprawl and Related Problems: Bibliometric Analysis and Refined Analysis from 1991 to 2011

To shed light on the general patterns and trends in urban sprawl research,and to provide reference for future study,bibliometric analysis and refined analysis are conducted for publications in this area from 1991 to 2011.The general publication output,the global geographical distribution of the authors,the funding and institutions involved,the research areas,and the source titles are analyzed and discussed.Scholars in the United States and China have produced most of the documents in urban sprawl and these two countries are also the largest contributors in terms of funding and institutions.′Environmental Sciences&Ecology′,′Urban Studies′,and′Geography′are the most common research areas,and the journal titled Urban Studies has contributed the most articles.Furthermore,the refined analyses on the 500 top-cited and most relevant publications have revealed that research on urban sprawl is closely associated with the categories of′Urban form and development′,′Land use/land development′and′environment/ecology/biology′.Conclusions are made with respect to the basic paradigm of research on urban sprawl.The multi-disciplinary research into urban sprawl are expected to be more diversified and integrated.

Delineation of urban growth boundary based on FLUS model under the perspective of land use evaluation in hilly mountainous areas

With rapid economic development,the size of urban land in China is expanding dramatically.The Urban Growth Boundary(UGB)is an expandable spatial boundary for urban construction in a certain period in order to control the urban sprawl.Reasonable delineation of UGB can inhibit the disorderly spread of urban space and guide the normal development of the city.It is of practical significance for the construction of green urban space.The study utilizes GIS technology to establish a land construction suitability evaluation system for Nankang city,which is experiencing rapid urban expansion,and outlines the preliminary UGB under the future land use simulation(FLUS)model.At the same time,considering the coupled coordination of"Production-Living-Ecological Space",and based on the suitability evaluation,we revised the preliminary UGB by combining the advantages of the patch-generating land use simulation(PLUS)model and the convex hull model to delineate the final UGB.The results show that:1)the comprehensive score of the evaluation of the suitability of the construction of land from high to low shows the distribution of the center of the city to the surrounding circle type spread,the center of the city has the highest suitability score.The results of convex hull model show that the urban expansion type of Nankang is epitaxial.In the future,the urban expansion will mainly occur in the northern part of the city.The PLUS model predicts an increase of 3359.97 hm^(2)of construction land in Nankang by 2035,of which 2022.97 hm^(2)is urban construction land.2)The FLUS model has a prediction accuracy of 86.3%and delineates a preliminary UGB area of 9215.07 hm^(2).3)We used the results of the construction suitability evaluation,PLUS model simulation results,and convex hull model predictions to revise the originally delineated UGB.The final delineated UGB area is 8895.67 hm^(2)and it is capable of meeting the future development of the study area.The results of the delineation can promote sustainable urban development,and the delineation methodology can provide a reference basis for the preparation of territorial spatial planning.

城市蔓延对生态系统服务流的影响研究进展及对长江流域的启示

全面梳理城市蔓延对生态系统服务流的影响研究现状,有利于促进区域社会经济可持续发展。综述了城市蔓延对生态系统服务流的影响研究,结果表明:城市蔓延对生态系统服务流的影响研究仍处于起步阶段。城市蔓延通过载体传递和流动路径两方面改变了生态系统服务流的流量、流速和流向,导致生态系统服务流总量的减少和空间异质性的增加;城市蔓延的单项指标变化、城市蔓延的尺度以及城市蔓延的多情景模拟是探索城市蔓延对生态系统服务流影响过程的主要切入点;城市蔓延过程中引起的生态系统服务流扩散效应主要源于土地利用类型的变化和人类居住模式的改变。已有研究在一定程度上解释了城市蔓延对生态系统服务流的影响,但在揭示影响机理、剖析影响过程、评估影响效应以及探索生态系统服务流合理分配以促进城市可持续发展等方面的研究还存在较大空白。在此前提下,未来应基于“机理揭示-影响模拟-效应评估”的研究思路,建立长江流域城市蔓延对生态系统服务流影响研究框架,探索长江流域城市可持续发展与生态系统服务流的合理分配方案,实现长江流域生态保护与社会发展的协同共进。

新型城镇化建设与城市低碳治理——基于国家新型城镇化综合试点政策实施的准自然实验

新型城镇化是消除快速城镇化弊端、科学推进城镇化发展的重要抓手。利用2007—2019年206个地级及以上城市数据,以国家新型城镇化综合试点政策的实施为新型城镇化建设的准自然实验,运用多期双重差分方法实证分析了新型城镇化建设对城市低碳治理的影响。研究发现:新型城镇化建设显著抑制了城市碳排放,国家新型城镇化综合试点政策促使试点城市的碳排放强度平均下降了3.02%,并且随着政策的推进其效果逐渐增强。异质性分析发现,新型城镇化建设仅对东部城市、中部城市以及大城市的碳排放强度具有显著的抑制作用。机制分析发现,新型城镇化建设主要通过抑制城市蔓延、促进经济集聚、强化环境规制降低城市碳排放强度。因此,建议地方政府加快推进新型城镇化多维目标考核,加大节约集约用地与环境监管力度,探索区域间差异化的新型城镇化推进路径,最终实现城镇的低碳发展。

城市蔓延对绿色发展的影响

基于2006—2019年中国284个城市的面板数据,通过构建双向固定效应模型、门槛效应模型和空间计量模型,实证检验了城市蔓延对绿色发展的影响。研究发现,城市蔓延对绿色发展具有显著的负向影响,且该结论在经过一系列稳健性检验之后依然成立;城市蔓延对绿色发展的影响存在异质性,对中东部地区、未开通高铁城市、中小城市的绿色发展的负向影响更加显著;城市蔓延对绿色发展的影响存在单一门槛效应,适度的城市蔓延有助于促进绿色发展水平的提升,但过度的城市蔓延则会对绿色发展产生不利影响。城市蔓延对绿色发展存在显著的空间溢出效应,会抑制本地及邻近地区的绿色发展。基于此,提出科学合理地划定城市蔓延边界、因地制宜地制定城市蔓延调控策略以及加强城市间城市蔓延调控的协同效应等对策建议,以提升城市绿色发展水平。

Spatiotemporal dynamics of the urban sprawl in a typical urban agglomeration： a case study on Southern Jiangsu, China （1983-2007）

China has experienced urbanization at an unprecedented rate over the past decades. Against this background, this paper demonstrates the multi-level spatiotemporal urban sprawl process from 1983 to 2007 on the perspective of urban agglomeration with a case study in Southern Jiangsu. Based on a combination of eight rounds of satellite images from 1983 to 2007, the presented results suggest the following three main findings： （1） At the prefecture-city level, the urban sprawl in Southern Jiangsu has presented significantly divergent growth patterns, with more than half of this vast growth occurring in the Suzhou prefecture-level city. （2） At the county level, clear spatial differentiations exist in the direction of the urban sprawl. The centroids of all county seats in the Suzhou and Wuxi prefecture-level cities have an eastward tendency （Shanghai oriented）, while those of the county seats in the Changzhou prefecture-level city tend to be westward （Nanjing oriented）. （3） At the township level, two convergent groups have gradually formed over time; namely, the low density urban zone in the western hilly land and the high density urban zone around the three central downtown areas. The urban areas close to urban cores tend to merge, showing a high-density convergent growth pattern, as do the western and southwestern townships in Southern Jiangsu, showing a low-density convergent growth pattern. All of these findings may be valuable for researchers and local authorities in providing reference for regional coordinated growth, environmental management, and urban planning decision-making.

Modeling sprawl of unauthorized development using geospatial technology: case study in Kuantan district, Malaysia

The paper explores a framework combining remote sensing and GIS-cellular automata(CA)concepts aimed at improving the modeling of unauthorized land use sprawl.Remote sensing data have been used in urban modeling and analysis,the use of high-resolution remote sensing data in assessing unauthorized development is quite unexplored.This work has demonstrated systematic combination utilization of geospatial analyses tools to acquire a new level of information to enable urban modeling and sprawl analysis in assisting urban sustainable management.In this study,Kuantan city,Malaysia was selected in simulation of the unauthorized land use with CA concept for a period of 15 years(2000
2015),with main input time-series land use observation from 1995 to 2005.The 2000 and 2005 land use input was also used as calibrated and test assessment of the simulation.The results show excellent agreement between in-situ changes of the unauthorized land use classes and the corresponding simulated classes within the same periods.In conclusion,CA model can lead to new levels of understanding of how urban areas grow and change as in view of digital earth aspiration.