Urban Expansion Pattern and Land Use Dynamics in Dhaka, 1989–2014

Rapid change in land use and land cover (LULC) and unplanned urban expansion in Dhaka City, Bangladesh, receives continuous attention from local policymakers and the international community. This study employed a supervised classification procedure and postclassification change detection technique to estimate major changes between different LULC classes. The study revealed that built-up area increased significantly from 1989 to 2014. The total urban growth of 81.54 percent resulted in a substantial decrease in natural vegetation cover and agricultural land. In addition, water bodies have declined consistently over the last twenty-five years. The overall accuracy of LULC change maps produced from Landsat data ranged from 89.72 percent to 92.97 percent. The results should contribute to ongoing LULC information updates while forecasting possible future LULC change and sustainable development under greater population density.     

Unplanned urban growth: land use/land cover change in the Guwahati Metropolitan Area,India

Unplanned urban growth, particularly in developing countries has led to changes in land use/land cover (LULC). Numerous Indian cities face problems of unplanned LULC change due to nominal or non-existent planning efforts compounded by rapid urban population growth. The Guwahati Metropolitan Area (GMA) is one such urban centre. The present study assesses the trajectories of LULC change using Landsat imageries acquired in 1976, 1989, 2002 and 2015. Natural and semi natural vegetated area and artificial and natural water bodies decreased while built-up areas, cultivated and managed areas, and natural and semi natural non-vegetated areas increased. The built-up area increased from 23.9 in 1976 to 115.1 km² in 2015 becoming the dominant land cover class accounting for 41.8% of the total geographical area. During this period, natural and semi natural vegetated land were reduced by 88.9 km² at an annual rate of 2.2 km². Over the years there was an increasing trend of built-up land and cultivated and managed areas in the peripheral areas of the city while natural and semi natural vegetated land diminished. Consequently, as in many other developing countries, there is an urgent need for the governmental authorities and other stakeholders to implement effective urban planning policies.     

Land Cover Status in the Koshi River Basin,Central Himalayas

The Koshi River Basin is in the middle of the Himalayas, a tributary of the Ganges River and a very important cross-border watershed. Across the basin there are large changes in altitude, habitat complexity, ecosystem integrity, land cover diversity and regional difference and this area is sensitive to global climate change. Based on Landsat TM images, vegetation mapping, field investigations and 3S technology, we compiled high-precision land cover data for the Koshi River Basin and analyzed current land cover characteristics. We found that from source to downstream, land cover in the Koshi River Basin in 2010 was composed of water body (glacier), bare land, sparse vegetation, grassland, wetland, shrubland, forest, cropland, water body (river or lake) and built-up areas. Among them, grassland, forest, bare land and cropland are the main types, accounting for 25.83%, 21.19%, 19.31% and 15.09% of the basin’s area respectively. The composition and structure of the Koshi River Basin land cover types are different between southern and northern slopes. The north slope is dominated by grassland, bare land and glacier; forest, bare land and glacier are mainly found on northern slopes. Northern slopes contain nearly seven times more grassland than southern slopes; while 97.13% of forest is located on southern slopes. Grassland area on northern slope is 6.67 times than on southern slope. The vertical distribution of major land cover types has obvious zonal characteristics. Land cover types from low to high altitudes are cropland, forest, Shrubland and mixed cropland, grassland, sparse vegetation, bare land and water bodies. These results provide a scientific basis for the study of land use and cover change in a critical region and will inform ecosystem protection, sustainability and management in this and other alpine transboundary basins.     

Land Changes Fostering Atlantic Forest Transition in Brazil: Evidence from the Paraíba Valley

The Atlantic Forest biome has only 13 percent of its pristine vegetation cover left. This article analyzes the consequences of land changes on forest cover in the Paraíba Valley, São Paulo state, Brazil, from 1985 to 2011. Multitemporal satellite image classifications were carried out to map eight land use and land cover classes. The forest cover increased from 2,696 km² in 1985 to 4,704 km² in 2011, mostly over areas of degraded pastures. The highest rates of afforestation were observed within protected areas around eucalyptus plantations. On the other hand, deforestation processes were concentrated on areas covered by secondary forests. Socioeconomic changes taking place in particular Brazilian settings, such as industrialization and agricultural modernization, allied to the Paraíba Valley's natural biophysical constraints for agricultural production, have led the region to experience a remarkable case of forest transition.     

A geospatial approach to assessing land change in the built-up landscape of Wa Municipality of Ghana

ABSTRACT

Urban landscapes are changing in response to changes in socio-economic conditions. Land change scientists seek to understand these land dynamics in the coupled human-environment system of urban landscapes. This study assessed land change in the built-up area of Wa Municipality between 1986 and 2016 using Landsat images. We used the Support Vector Machine algorithm for classifying the images. We recorded image classification accuracies of 97%, 95%, 92% and 96% for the 1986, 1996, 2006 and 2016 classified images, respectively. Our study finds that over the 1986–2016 period, agricultural land and bare land transitioned to build-up land by 9.23% and 3.79%, respectively, as compared to 2.79% for vegetation and 0.05% for water. Our in-municipal level analysis thus shows that urban landscapes could expand more sustainably by targeting other dominant land categories instead of the vegetation cover. The findings in this paper could serve as a spatial model for planning and reducing the unintended socio-ecological impacts of expansion in the built-up area.     

Remotely sensing the spatial and temporal land cover changes in Eastern Mau forest reserve and Lake Nakuru drainage basin,Kenya

This study aimed at characterizing land cover dynamics for four decades in Eastern Mau forest and Lake Nakuru basin, Kenya. The specific objectives were to: (i) identify and map the major land cover types in 1973, 1985, 2000 and 2011; (ii) detect and determine the magnitude, rates and nature of the land cover changes that had occurred between these dates, and; (iii) establish the spatial and temporal distribution of these changes. Land cover types were discriminated through partitioning, hybrid classification and spatial reclassification of multi-temporal Landsat imagery. The land cover products were then validated and overlaid in post-classification comparison to detect the changes between 1973 and 2011. The accuracies of the land cover maps for 1973, 1985, 2000 and 2011 were 88%, 95%, 80% and 89% respectively. Six land cover classes, namely forests-shrublands, grasslands, croplands, built-up lands, bare lands and water bodies, were mapped. Forests-shrublands dominated in 1973, 1985 and 2000 covering about 1067 km², 893 km² and 797 km² respectively, but were surpassed by croplands (953 km²) in 2011. Bare lands occupied the least area that varied between 2 km² and 7 km² during this period. Overall, forests-shrublands and grasslands decreased by 428 km² and 258 km² at the annual average rates of 1% each, whereas croplands and built-up lands expanded by 660 km² and 24 km² at the annual rates of 6% and 16% respectively. The key hotspots of these changes were distributed in all directions of the study area, but at different times. Therefore, policies that integrate restoration and conservation of natural ecosystems with enhancement of agricultural productivity are strongly recommended. This will ensure environmental sustainability and socio-economic well-being in the area. Future research needs to assess the impacts of the land cover changes on ecosystem services and to project the future patterns of land cover changes.     

Radiative forcing over China due to albedo change caused by land cover change during 1990-2010

Land cover change affects surface radiation budget and energy balance by changing surface albedo and further impacts the regional and global climate. In this article, high spatial and temporal resolution satellite products were used to analyze the driving mechanism for surface albedo change caused by land cover change during 1990-2010. In addition, the annual-scale radiative forcing caused by surface albedo changes in China's 50 ecological regions were calculated to reveal the biophysical mechanisms of land cover change affecting climate change at regional scale. Our results showed that the national land cover changes were mainly caused by land reclamation, grassland desertification and urbanization in past 20 years, which were almost induced by anthropogenic activities. Grassland and forest area decreased by 0.60% and 0.11%, respectively. The area of urban and farmland increased by 0.60% and 0.19%, respectively. The mean radiative forcing caused by land cover changes during 1990-2010 was 0.062 W/m2 in China, indicating a warming climate effect. However, spatial heterogeneity of radiative forcing was huge among different ecological regions. Farmland conversing to urban construction land, the main type of land cover change for the urban and suburban agricultural ecological region in Beijing-Tianjin-Tangshan region, caused an albedo reduction by 0.00456 and a maximum positive radiative forcing of 0.863 W/m2, which was presented as warming climate effects. Grassland and forest conversing to farmland, the main type of land cover change for the temperate humid agricultural and wetland ecological region in Sanjiang Plain, caused an albedo increase by 0.00152 and a maximum negative radiative forcing of 0.184 W/m2, implying cooling climate effects.     

When Fields Revert to Forest: Development and Spontaneous Reforestation in Post-War Puerto Rico

During the past 50 years forests have recolonized extensive areas of Puerto Rico. Between 1950 and 1990 forest cover increased from 9% to 37% of the island's land area. In proportional terms more land has reverted to forest in Puerto Rico than anywhere else on earth during the second half of the twentieth century. This paper explores the geography of this process by matching changes in land cover with the characteristics of the land and communities in Puerto Rico. The reversion of agricultural lands to forest occurred most frequently in humid, upland, coffee-growing regions characterized by heavy out-migration and populations of smallholders who earned some of their income from off-farm sources. These findings suggest that changes in non-farm labor markets, as well as changes in the political economy of agriculture, have important impacts on the prospects for converting agricultural lands into forests.     

When Fields Revert to Forest: Development and Spontaneous Reforestation in Post‐War Puerto Rico

During the past 50 years forests have recolonized extensive areas of Puerto Rico. Between 1950 and 1990 forest cover increased from 9% to 37% of the island's land area. In proportional terms more land has reverted to forest in Puerto Rico than anywhere else on earth during the second half of the twentieth century. This paper explores the geography of this process by matching changes in land cover with the characteristics of the land and communities in Puerto Rico. The reversion of agricultural lands to forest occurred most frequently in humid, upland, coffee‐growing regions characterized by heavy out‐migration and populations of smallholders who earned some of their income from off‐farm sources. These findings suggest that changes in non‐farm labor markets, as well as changes in the political economy of agriculture, have important impacts on the prospects for converting agricultural lands into forests.     

Spatio-Temporal Analysis of Land Use/Land Cover Changes in an Ecologically Fragile Area—Alappuzha District,Southern Kerala,India

Concomitant with careless human interference in the delicate environmental balance, the Earth’s surface is witnessing a variety of changes in land use and land cover (LULC). Acquisition of a sound understanding of LULC is an important aspect of maintaining a sustainable, benign, healthy environment. The present work highlights a spatiotemporal study on the LULC features of Alappuzha District, an ecologically fragile area in southern Kerala, a state in South India. The study area faces diverse environmental challenges including decline of landforms, rising sea levels, population expansion and anthropogenic encroachments on the ecological balance. This investigation compiles an audited account of the modifications, in each class of LULC, using geospatial technologies. We interpreted satellite imagery from the Landsat 8 and the Landsat multispectral scanner for the years 1973 and 2017. The LULC aspects were categorized into seven classes: waterbody, waterlogged area, mixed vegetation, built-up land, uncultivated area, paddy field and sandy area. Our findings affirm that the expansiveness of the built-up land area is directly proportional to the growth of the population. Advanced technologies such as remote sensing and geographic information system accentuate alterations in land use patterns over time and the extent to which the changes affect the human population and the natural habitat. We verified the results of our research by assessment of accuracy and ground truth confirmation of the LULC features.

     

Identifying sustainability challenges on land and water uses: The case of Lake Ziway watershed,Ethiopia

This paper firstly analyzes the land use - land cover (LULC) in Lake Ziway watershed (Ethiopia) and quantifies the changing patterns from 1973 to 2014 using Landsat images. Secondly, the paper estimates sediment yields using the Soil and Water Assessment Tool (SWAT model). It also assesses and estimates water abstraction from Lake Ziway using survey data. The study shows that the conversions from woodlands into agricultural lands and settlement areas are the major detected LULC changes. Of the total area of the watershed, agricultural lands and settlement areas together increased from 57% in 1973 to 75% in 2014 at the expense of woodlands whose areas decreased from 26.16% to 6.63% in the study periods. The study also shows that water abstraction and sediment loads are increasing at Lake Ziway watershed. The major driving forces behind these LULC changes and the impacts on the lake natural condition are anthropogenic factors such as population growth, land policy changes and deforestation. Increasing demands for more land and water resources, i.e., land for settlements and cultivation, wood for fuel and charcoals, and water for irrigation and municipal water supply, are the underlying causes for the observed changes on the watershed resources. Thus, if the existing scenarios of human pressures are left neglected without management interventions, severe watershed degradations will continue to further affect the watershed's resources including the hydrology. Therefore, responsible government institutions should start mobilizing the local communities along with providing financial and material supports for watershed rehabilitation through afforestation and soil and water conservation activities. Additionally, the free-access practices for water use should be replaced by user-charge policy to regulate water abstractions in order to adequately sustain the water level of Lake Ziway and its feeder rivers. In this respect, this study provides firsthand information to policy makers and planners to put in place a comprehensive land and water use plan and regulations against the unruly human actions in the watershed before irreversible losses might happen to Lake Ziway and its watershed resources.     

黄土台塬区土地利用转移流及空间集聚特征分析

提出了土地利用转移流和土地利用活跃度的概念,基于Landsat 遥感影像数据,采用土地利用变化测度模型,以5 年和25 年两种时间尺度对黄土台塬区土地利用时空动态特征进行分析,并将密度制图法应用到土地利用变化的空间集聚特征识别中.研究表明：① 黄土台塬区耕地占绝对优势,后备耕地资源严重不足,林地、草地、水域比例较低,存在较大生态风险;② 耕地与建设用地、草地、林地之间的转移关系是黄土台塬区土地利用转移的关键关系,决定着台塬区土地利用变化特征;③ 1985-2010 年耕地转建设用地流高达26668.80 hm²,占土地转移流40.75%,草地转耕地流18923.90 hm²,占28.91%,建设占用耕地情况严重,耕地占补平衡主要通过挤占草地实现;④ 25 年以来,土地利用变化对水域扰动最大,其次为森林,草地第三;⑤ 土地利用变化存在阶段性,1990-2000 年土地利用变化速率高于其他时段;⑥不同时间尺度下土地利用变化的空间集聚特征不同,25 年尺度下城镇附近土地变化幅度较高,5 年尺度下土地利用变化热点区由台塬中部向东西边缘区推移.     

Land use/land cover change detection and prediction in the north-western coastal desert of Egypt using Markov-CA

Detecting land-use change has become of concern to environmentalists, conservationists and land use planners due to its impact on natural ecosystems. We studied land use/land cover (LULC) changes in part of the northwestern desert of Egypt and used the Markov-CA integrated approach to predict future changes. We mapped the LULC distribution of the desert landscape for 1988, 1999, and 2011. Landsat Thematic Mapper 5 data and ancillary data were classified using the random forests approach. The technique produced LULC maps with an overall accuracy of more than 90%. Analysis of LULC classes from the three dates revealed that the study area was subjected to three different stages of modification, each dominated by different land uses. The use of a spatially explicit land use change modeling approach, such as Markov-CA approach, provides ways for projecting different future scenarios. Markov-CA was used to predict land use change in 2011 and project changes in 2023 by extrapolating current trends. The technique was successful in predicting LULC distribution in 2011 and the results were comparable to the actual LULC for 2011. The projected LULC for 2023 revealed more urbanization of the landscape with potential expansion in the croplands westward and northward, an increase in quarries, and growth in residential centers. The outcomes can help management activities directed toward protection of wildlife in the area. The study can also be used as a guide to other studies aiming at projecting changes in arid areas experiencing similar land use changes.     

Different times,same story: Native forest loss and landscape homogenization in three physiographical areas of south-central of Chile

Temperate forest represents the smallest area among the main world's forest biomes, but is one of those most threatened by forest loss. Chile contains most of the temperate forest in South America and more than half of the temperate forest in the southern hemisphere. Chilean temperate forest is considered to be one of the world's biodiversity hotspots. In this study we assessed the rate of land use and land cover (LULC) change over time, identified the main LULCs replacing native forest, and described how changes have evolved in contrasting physiographical conditions and through different historical phases of the landscape over the last 40 years. To achieve this, we analysed LULC change with particular focus on forest cover in three areas representing different physiographical conditions and histories of human occupation in the Araucanía Region of Chile, namely the Central Valley, the Coastal range, and the Andean range. We found substantial differences in temporal and intra-regional patterns of forest loss and LULC change. In the Central Valley, forest loss started long ago, and the area occupied by native forest nowadays is less than 5% of the landscape. In the Coastal range, rapid land cover change has taken place since 1973, with an increasing rate of forest loss over time. We detected a similar but less intense pattern in the forests of the Andean range. Overall, the general pattern points to a process of landscape homogenization in all three physiographical areas. Exotic tree plantations have spread over large geographical areas, becoming the dominant land cover. Land cover change in the Araucanía Region reflects a model of change in which areas with better environmental conditions and accessibility are occupied first for productive activities. As the availability of suitable areas for the expansion of productive activities diminishes, these activities start to move into physiographical areas which were previously “protected” by adverse environmental conditions or poor accessibility. This model of production growth could lead to the complete deforestation of areas outside national protected areas, and other areas which still remain inaccessible due to technological restrictions on exploitation.     

1990-2010年中国土地覆被变化引起反照率改变的辐射强迫

土地覆被变化通过改变地表反照率而影响地表辐射收支与能量平衡,从而对区域和全球气候产生影响。本文利用高时空分辨率遥感数据分析1990-2010 年中国土地覆被变化改变地表反照率的时空驱动机制,并计算全国50 个生态区地表反照率变化导致的年际尺度辐射强迫,揭示土地覆被变化在生态区尺度上影响气候变化的生物地球物理机制。结果表明:1990-2010 年全国土地覆被变化以耕地开垦、草地沙化、城市化等人类土地利用活动导致的土地覆被变化最为明显,全国草地与林地面积分别减少了0.60%和0.11%;建设用地和耕地面积分别增加了0.60%和0.19%。全国土地覆被变化通过改变地表反照率引起的平均辐射强迫为0.062 W/m²,表现为增温的气候效应,但在生态区尺度辐射强迫空间差异很大。京津唐城镇与农城郊农业生态区主要土地覆被变化为耕地转为建设用地,引起地表反照率降低了0.00456,产生0.863 W/m²的辐射强迫,表现为增温的气候效应;而三江平原温带湿润农业与湿地生态区主要的土地覆被变化为林草地转为耕地,引起地表反照率升高了0.00152,产生-0.184 W/m²的辐射强迫,表现为降温的气候效应。     

改革开放40 a来新疆土地覆被变化的空间格局与特征

改革开放40 a以来,新疆土地利用和地表覆被发生了巨大变化,在产生巨大社会经济效益的同时,也产生了许多生态与环境问题。为了给未来新疆土地利用、水资源开发及社会经济可持续发展国土空间规划提供依据,通过采用分区分层的决策树方法和向量相似度的变化检测方法,完成了新疆2015年、2010年、2000年、1990年、1975年的土地覆被1∶100 000矢量数据集,准确反演了过去40 a（改革开放40 a）来新疆地表覆被变化过程,分析了新疆土地覆被变化与国家改革开放政策相互关系,从垦荒（1975—1990年）、农业资源开发（1990—2000年）、西部大开发（2000—2010年）、对口援疆（2010—2015年）4个阶段,阐述了国家政策力度和导向对土地覆被变化的影响。分析表明：新疆土地覆被变化由耕地开垦、人工表面增长的高速发展模式开始向兼顾生态文明建设的可持续发展方向转型,各主要地类的变化也由急剧发展转向基本可控。近40 a新疆耕地面积增加了128%（50 414.02 km²）,新增耕地依照水土资源配置特征,遵循空间规律分布;人工表面（建设、交通、工矿用地）面积增加了197%（7 497.11 km²）,在2000年后增速明显,2010年后南疆增加幅度很大;1990年前林地面积呈现减少趋势,1990年后呈增加的态势,新增林地广泛分布在全疆天然林封育保护范围和天保工程实施区内;湿地1990年前面积减少明显,1990—2000年保持稳定,2000年后呈增加趋势;草地和其他类型的面积呈现持续减少态势。     

江汉平原土地利用的时空变化及其驱动因素分析

采用遥感、GIS一体化技术,利用1989～1990、1995～1996和1999～2000年获取的三期陆地资源卫星图像,对江汉平原土地利用10年变化和以1995～1996年为界的前后两个5年变化的时空特征进行了分析,并探讨了变化的驱动因素。结果表明,该区的土地利用在不同的时间及空间尺度上有明显不同的特点。10年间,耕地减少近5万hm²,其中,前5年的减少量占多数,达6783%。各类建设用地总计增加了156万hm²,其中,前5年的增加量是后5年的2倍。水域面积在10年间增加了达到354万hm²,后5年的增幅不到前期的1/2。土地利用变化最快的区域均处于工业经济较发达、城市化较快的地区如武汉、仙桃,变化最慢的区域在监利、松滋、天门等地。政策、社会经济与科技因素对土地利用随时间尺度的变化有决定性的影响。     

Spatio-temporal dynamics of land cover and land surface temperature in Ganges-Brahmaputra delta: A comparative analysis between India and Bangladesh

Land use and land cover (LULC) change in the Ganges-Brahmaputra delta (GBD) poses significant challenges towards future environmental sustainability of the region and requires regional scale monitoring of key bio-physical variables and changes in their inter-relationship over space and time. Focusing on the southern part of the lower GBD region along the international border of India and Bangladesh, this study examined the spatio-temporal variability of LULC change and its relationship with Land Surface Temperature (LST). Furthermore, LULC-LST relationships were compared between Indian and Bangladesh part and its trend in and around big cities (with more than 1 million population) and towns (with more than 100,000 population) was investigated. Results showed that LST changes were predominantly driven by LULC changes on both sides of the border. Urban growth is the dominant form of LULC change, and the rate of land change was faster in 2005–2010 time period than 1989–2005. Over the period of 21 years, mean January LST decreased by approximately 1.83 °C in Indian part and 1.85 °C in the Bangladesh part. Areas that changed from to rural from agricultural experienced decrease in mean LST, whereas those areas that changed to urban from either agriculture or rural, experienced increase in mean LST. The relationship between LULC and LST are same on both sides of the Indo-Bangladesh border. In bigger cities like Kolkata (in India) and Khulna (in Bangladesh), there is a high spatial variability in relationship between LULC and LST compared to large towns. The LULC-LST relationship in large towns in India was influenced by proximity to Kolkata and coastal areas, whereas in Bangladesh no such influence was evident. The results and the data produced in this study are crucial for monitoring LULC changes, for developing spatial decision support system, and thus will be helpful to address the current challenges of land management in the GBD region. Changes in the LULC and LST are important indicators of GBD's environmental health and access its vulnerability and thus the present findings serve as baseline information for future studies seeking to examine the impact of differential policies on the LULC change in the region.     

2000-2010年亚欧大陆中低纬度海岸带土地利用/覆盖变化及驱动力分析

土地利用/覆盖变化是全球变化研究的重要问题,而海岸带则是该领域研究的热点区域。以三套土地利用/覆盖数据（MCD12Q1、CCI-LC和GlobeLand30）为基础,采用基于一致性分析和模糊集合理论的数据融合方法,获取2000年和2010年亚欧大陆中低纬度海岸带土地利用/覆盖分类信息,进而分析土地利用/覆盖变化特征及驱动因素。结果表明：十年间亚欧大陆中低纬度海岸带土地利用/覆盖变化方式主要以耕地萎缩和林地扩张为主,其次是湿地扩张,再次是草地和裸地萎缩,最后是灌木地和人造地表扩张;土地利用/覆盖类型之间的相互转换面积较小,仅占研究区总面积的4.22%,其中分布面积占优势的变化类型为耕地–林地–草地相互转换、灌木地–裸地相互转换、林地转为湿地以及林地转为灌木地等。地形因素、气候分异等自然驱动力深刻影响着土地利用/覆盖变化的宏观格局,而人口压力增大、经济高速发展、政策的颁布与实施等人文驱动力则是推动十年间亚欧大陆中低纬度海岸带土地利用/覆盖变化的主要原因。     

Soy,Cotton, and the Final Atlantic Forest Frontier

From 1945 to 2000, the extent of Paraguay's Atlantic Forest was reduced from 73,000 to 12,000 square kilometers. Deforestation rates were exceptionally high from the late 1960s through to the end of the century. During this period, dual agricultural frontiers pushed into the region from both east and west, resulting in a production landscape defined by two principal commodities: soybeans and cotton. This article considers the expansion and contraction of these industries and addresses their impacts on the region's forest cover. Findings suggest that the role of cotton and smallholder agriculture has been greatly diminished as a driver of land cover change in the region since 1990. High rates of forest loss were sustained, however, partly as a result of continued pressure for agricultural expansion for soy production.