scholarly journals Human Activities Enhance Radiation Forcing through Surface Albedo Associated with Vegetation in Beijing

2020 ◽  
Vol 12 (5) ◽  
pp. 837 ◽  
Author(s):  
Xiying Tang ◽  
Yaoping Cui ◽  
Nan Li ◽  
Yiming Fu ◽  
Xiaoyan Liu ◽  
...  
Keyword(s):  
Land Cover ◽  
Human Activities ◽  
Urban Areas ◽  
Radiative Forcing ◽  
Surface Albedo ◽  
Urban Expansion ◽  
Radiation Energy ◽  
Vegetation Growth ◽  
Land Cover Types ◽  
The Impact

The impact of human activities on vegetation has been the focus of much research, but the impact on radiation energy through surface albedo associated with vegetation greenness and length of the growth season is still not well documented. Based on the land cover data for the years 2000 and 2015, this study first divided the land cover change in Beijing from 2000 to 2015 into five types according to the impact of human activities and vegetation resilience, namely, old urban areas (OU), urban expansion areas (UE), cropland (CP), mixed pixel areas (MP, which means the land covers other than urban expansion which had changed from 2000 to 2015), and the residual vegetation cover areas (pure pixels (PP), dominated by natural and seminatural vegetation, such as grassland, forest, and wetland). Then, we calculated the direct radiative forcing from the albedo change from 2000 to 2015 and analyzed the effect of vegetation on the albedo under different land cover types based on multi-resource Moderate Resolution Imaging Spectroradiometer (MODIS) products of vegetation, albedo, and solar radiation. The results showed that the most typical changes in land cover were from urban expansion. By comparing the PP with the four human-affected land cover types (OU, UE, MP, and CP), we confirmed that the radiative forcing increment between 2001–2003 and 2013–2015 in PP (0.01 W/m2) was much smaller than that in the four human-affected land cover types (the mean increment was 0.92 W/m2). This study highlights that human activities affected vegetation growth. This, in turn, brought changes in the albedo, thereby enhancing radiative forcing in Beijing during 2000–2015.

scholarly journals Spatiotemporal Variability of Land Surface Albedo over the Tibet Plateau from 2001 to 2019

2020 ◽  
Vol 12 (7) ◽  
pp. 1188
Author(s):  
Xingwen Lin ◽  
Jianguang Wen ◽  
Qinhuo Liu ◽  
Dongqin You ◽  
Shengbiao Wu ◽  
...  
Keyword(s):  
Climate Change ◽  
Time Series ◽  
Land Cover ◽  
Snow Cover ◽  
Land Surface ◽  
Radiative Forcing ◽  
Surface Albedo ◽  
Tibet Plateau ◽  
Land Cover Types ◽  
Yearly Average

As an essential climate variable (ECV), land surface albedo plays an important role in the Earth surface radiation budget and regional or global climate change. The Tibetan Plateau (TP) is a sensitive environment to climate change, and understanding its albedo seasonal and inter-annual variations is thus important to help capture the climate change rules. In this paper, we analyzed the large-scale spatial patterns, temporal trends, and seasonal variability of land surface albedo overall the TP, based on the moderate resolution imaging spectroradiometer (MODIS) MCD43 albedo products from 2001 to 2019. Specifically, we assessed the correlations between the albedo anomaly and the anomalies of normalized difference vegetation index (NDVI), the fraction of snow cover (snow cover), and land surface temperature (LST). The results show that there are larger albedo variations distributed in the mountainous terrain of the TP. Approximately 10.06% of the land surface is identified to have been influenced by the significant albedo variation from the year 2001 to 2019. The yearly averaged albedo was decreased significantly at a rate of 0.0007 (Sen’s slope) over the TP. Additionally, the yearly average snow cover was decreased at a rate of 0.0756. However, the yearly average NDVI and LST were increased with slopes of 0.0004 and 0.0253 over the TP, respectively. The relative radiative forcing (RRF) caused by the land cover change (LCC) is larger than that caused by gradual albedo variation in steady land cover types. Overall, the RRF due to gradual albedo variation varied from 0.0005 to 0.0170 W/m2, and the RRF due to LCC variation varied from 0.0037 to 0.0243 W/m2 during the years 2001 to 2019. The positive RRF caused by gradual albedo variation or the LCC can strengthen the warming effects in the TP. The impact of the gradual albedo variations occurring in the steady land cover types was very low between 2001 and 2019 because the time series was short, and it therefore cannot be neglected when examining radiative forcing for a long time series regarding climate change.

scholarly journals Quantifying the Influences of Natural Factors and Human Activities on NDVI Changes in the Hanjiang River Basin, China

2020 ◽  
Vol 12 (22) ◽  
pp. 3780
Author(s):  
Ting Chen ◽  
Jun Xia ◽  
Lei Zou ◽  
Si Hong
Keyword(s):  
River Basin ◽  
Human Activities ◽  
Urban Areas ◽  
Vegetation Index ◽  
Vegetation Coverage ◽  
Vegetation Growth ◽  
Natural Factors ◽  
Range Type ◽  
Hanjiang River ◽  
The Impact

The Hanjiang River Basin (HJRB) is an important source area for drinking water in Hubei Province, China, and the vegetation coverage there is important to the ecological system. Due to the spatial heterogeneity and synergistic effect of various factors, it is very difficult to identify the main factors affecting vegetation growth in the HJRB. With the normalized difference vegetation index (NDVI) data from 2001 to 2018 in the HJRB, the spatiotemporal patterns of NDVI and the influences of natural factors and human activities on NDVI were investigated and quantified based on the Mann-Kendall (M-K) test, partial correlation analysis, and Geographical Detector. The individual factors and their interactions and the range/type of factor attributes suitable for vegetation growth were also examined. NDVI in the HJRB increased from 2001 to 2018, and the variation rate was 0.0046 year−1. NDVI was increasing in 81.17% of the area (p < 0.05). Elevation and slope can effectively explain the vegetation distribution. The interactions of factors on NDVI were significant, and the interactions of the elevation and precipitation can maximize the impact among all factors. The range of available landforms is thought to be highly conducive to vegetation growth. The rates of the annual precipitation and annual mean temperature changed from 2001 to 2018, which were 3.665 mm/year and 0.017 °C/year, and the regions where NDVI positively correlated with them were over 85%. Contrary to the general trend, NDVI has obviously decreased in urban areas since 2010. The quantitative findings of this study can help us better understand the effects of various factors on vegetation growth and provide appropriate suggestions for vegetation protection and restoration in the HJRB.

scholarly journals DYNAMICS OF SPATIO-TEMPORAL URBAN EXPANSION IN SOUTH WEST DELHI REGION: A GEO-SPATIAL APPROACH FOR URBAN DISASTER MANAGEMENT

2019 ◽  
Vol XLII-3/W8 ◽  
pp. 373-379
Author(s):  
N. Sharma ◽  
A. Kaur ◽  
P. Bose
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Natural Resources ◽  
Land Cover Change ◽  
Rural Areas ◽  
Urban Areas ◽  
Urban Expansion ◽  
Urban Disaster ◽  
Spatio Temporal ◽  
The Impact

<p><strong>Abstract.</strong> Constantly increasing population and up-scaling economic growth has certainly contributed to fast-paced urban expansion, but simultaneously, as a result, has developed immense pressure on our natural resources. Among other unfavorable consequences, this has led to significant changes in the land use and land cover patterns in megacities all across the globe. As the impact of uncontrolled and unplanned development continues to alter life patterns, it has become imperative to study severe problems resulting from rapid development and leading to environmental pollution, disruptions in ecological structures, ever increasing pressure on natural resources and recurring urban disasters This paper presents an approach to address these challenges using geospatial data to study the land use and land cover change and the patterns and processes of urban growth. Spatio-temporal changes in land-use/land-cover were assessed over the years using multi-date high resolution satellite data. The land use classification was conducted using visual image interpretation technique wherein, study area was categorized into five different classes based on NRSC classification system namely agricultural, built-up, urban green (forest), and fallow land and water bodies. Post-classification change detection technique was used for the assessment of land-cover change and transition matrices of urban expansion were developed to quantify the changes. The results show that the city has been expanding majorly in its borders, where land masses have been converted from agriculture based rural areas to urban structures. An increase in the built-up category was observed with the transformation of agricultural and marginal land with an approximate change of 8.62% in the peri-urban areas. Urban areas are becoming more densely populated and open barren lands are converted into urban areas due to over population and migration from the rural areas of Delhi and thus increasing threat towards urban disaster. Conservation and sustainable management of various natural resources is recommended in order to minimize the impact of potential urban disasters.</p>

scholarly journals Index-based Approach in Relation to Built-up and LST Dynamics; A Study of Lahore, Pakistan

2021 ◽  
Vol 12 (1) ◽  
pp. 32-40
Author(s):  
Kanwal Javid ◽  
Muhammad Ameer Nawaz Akram ◽  
Shazia Pervaiz ◽  
Rumana Siddiqui ◽  
Nausheen Mazhar
Keyword(s):  
Land Cover ◽  
Land Surface ◽  
Urban Areas ◽  
World View ◽  
Urban Expansion ◽  
Land Development ◽  
Water Bodies ◽  
Pollution Level ◽  
Area Index ◽  
Land Cover Types

In 21st century, cities outpaced in size and also in density due to development of economic sector. Consequently, the wide spread expansion of urban areas is resulting in the loss of productive green cover and water bodies. Therefore, realizing this alarming situation, the present study is aimed to investigate and evaluate the pattern of urban expansion by considering two major land cover types (i) built-up area (ii) other classes (vegetation, waterbody, soil etc.) during the last six years (2015-2020). For this study Sentinel imagery was acquired from USGS Earth Explorer, while Modis Terra images were acquired from World View NASA. New built-up area index (NBUI), normalized difference vegetation index (NDVI), worldview water index (WV-WI) and land surface temperature (LST) were calculated in order to analyze variations in Lahore’s major land cover types and its varying temperature patterns. Spatial analysis presented the obvious impacts of land development on Lahore. NBUI indicated that the built-up area has increased drastically from 34.0% in 2015 to 84.2% in 2020; NDVI analysis depicted a decline from 0.76% to 0.73%, in the green spaces of Lahore during the study period; WV-WI portrayed inconsistent values of water bodies, a gift of massive rise in the built-up area in Lahore. LST results presented that the temperature was 42.21°C in 2015, which simultaneously increased and recorded at 49.51°C in 2020. The increase in LST exhibited the alarming situation for urban environment and can become threat to increase the air pollution level in Lahore. Therefore, this study will serve as a snapshot for policy makers to control the menace of unplanned urbanization by formulating stringent policies to protect environment.

scholarly journals Spatial-Temporal Land Use and Land Cover Changes in Urban Areas Using Remote Sensing Images and GIS Analysis: The Case Study of Opole, Poland

Geosciences ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 312
Author(s):  
Barbara Wiatkowska ◽  
Janusz Słodczyk ◽  
Aleksandra Stokowska
Keyword(s):  
Remote Sensing ◽  
Land Use ◽  
Land Cover ◽  
Satellite Imagery ◽  
Urban Areas ◽  
Agricultural Land ◽  
Urban Expansion ◽  
Landsat 8 ◽  
Rate Of Increase ◽  
Management Procedures

Urban expansion is a dynamic and complex phenomenon, often involving adverse changes in land use and land cover (LULC). This paper uses satellite imagery from Landsat-5 TM, Landsat-8 OLI, Sentinel-2 MSI, and GIS technology to analyse LULC changes in 2000, 2005, 2010, 2015, and 2020. The research was carried out in Opole, the capital of the Opole Agglomeration (south-western Poland). Maps produced from supervised spectral classification of remote sensing data revealed that in 20 years, built-up areas have increased about 40%, mainly at the expense of agricultural land. Detection of changes in the spatial pattern of LULC showed that the highest average rate of increase in built-up areas occurred in the zone 3–6 km (11.7%) and above 6 km (10.4%) from the centre of Opole. The analysis of the increase of built-up land in relation to the decreasing population (SDG 11.3.1) has confirmed the ongoing process of demographic suburbanisation. The paper shows that satellite imagery and GIS can be a valuable tool for local authorities and planners to monitor the scale of urbanisation processes for the purpose of adapting space management procedures to the changing environment.

scholarly journals Mapping 20 Years of Urban Expansion in 45 Urban Areas of Sub-Saharan Africa

2021 ◽  
Vol 13 (3) ◽  
pp. 525
Author(s):  
Yann Forget ◽  
Michal Shimoni ◽  
Marius Gilbert ◽  
Catherine Linard
Keyword(s):  
Case Studies ◽  
Urban Areas ◽  
Urban Expansion ◽  
Local Population ◽  
Sub Saharan Africa ◽  
Annual Growth Rate ◽  
Urban Dynamics ◽  
Mapping Approach ◽  
Sub Saharan ◽  
The Impact

By 2050, half of the net increase in the world’s population is expected to reside in sub-Saharan Africa (SSA), driving high urbanization rates and drastic land cover changes. However, the data-scarce environment of SSA limits our understanding of the urban dynamics in the region. In this context, Earth Observation (EO) is an opportunity to gather accurate and up-to-date spatial information on urban extents. During the last decade, the adoption of open-access policies by major EO programs (CBERS, Landsat, Sentinel) has allowed the production of several global high resolution (10–30 m) maps of human settlements. However, mapping accuracies in SSA are usually lower, limited by the lack of reference datasets to support the training and the validation of the classification models. Here we propose a mapping approach based on multi-sensor satellite imagery (Landsat, Sentinel-1, Envisat, ERS) and volunteered geographic information (OpenStreetMap) to solve the challenges of urban remote sensing in SSA. The proposed mapping approach is assessed in 17 case studies for an average F1-score of 0.93, and applied in 45 urban areas of SSA to produce a dataset of urban expansion from 1995 to 2015. Across the case studies, built-up areas averaged a compound annual growth rate of 5.5% between 1995 and 2015. The comparison with local population dynamics reveals the heterogeneity of urban dynamics in SSA. Overall, population densities in built-up areas are decreasing. However, the impact of population growth on urban expansion differs depending on the size of the urban area and its income class.

scholarly journals Intra-annual variability of satellite observed surface albedo associated with typical land cover types in China

2014 ◽  
Vol 25 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Zhengjia Liu ◽  
Quanqin Shao ◽  
Jian Tao ◽  
Wenfeng Chi
Keyword(s):  
Land Cover ◽  
Surface Albedo ◽  
Land Cover Types ◽  
Annual Variability

Identifying land cover suitability factors for photovoltaic installations with focus on cropland and urban areas

2021 ◽  
Author(s):  
Madhura Yeligeti ◽  
Wenxuan Hu ◽  
Yvonne Scholz ◽  
Kai von Krbek
Keyword(s):  
Land Cover ◽  
Urban Areas ◽  
Energy Systems ◽  
Energy System ◽  
Climatic Conditions ◽  
System Modelling ◽  
Solar Photovoltaic ◽  
Land Cover Types ◽  
The World ◽  
Urban Settlements

&lt;p&gt;Solar photovoltaic (PV) systems will foreseeably be an integral part of future energy systems. Land cover area analysis has a large influence on estimatiin of long-term solar photovoltaic potential of the world in high spatial detail. In this regard, it is often seen in contemporary works, that the suitability of various land cover categories for PV installation is considered in a yes/no binary response. While some areas like natural parks, sanctuaries, forests are usually completely exempted from PV potential calculations, other land over categories like urban settlements, bare, sparsely vegetated areas, and even cropland can principally support PV installations to varying degrees. This depends on the specific land use competition, social, economic and climatic conditions, etc. In this study, we attempt to evaluate these &amp;#8216;factors of suitability&amp;#8217; of different land cover types for PV installations.&lt;/p&gt;&lt;p&gt;As a basis, the openly available global land cover datasets from the Copernicus Land Monitoring Service were used to identify major land cover types like cropland, shrubland, bare, wetlands, urban settlements, forests, moss and snow etc. For open area PV installations, with a focus on cropland, we incorporated the promising technology of &amp;#8216;Agri-voltaics&amp;#8217; in our investigation. Different crops have shown to respond positively or negatively, so far, to growing under PV panels according to various experimental and commercial sources. Hence, we considered 18 major crops of the world (covering 85% of world cropland) individually and consequently, evaluated a weighted overall suitability factor of cropland cover for PV, for three acceptance scenarios of future.&lt;/p&gt;&lt;p&gt;For rooftop PV installations in urban areas, various socio-economic and geographical influences come in play. The rooftop area available and further usable for PV depends on housing patterns (roof type, housing density) which vary with climate, population density and socio-economic lifestyle. We classified global urban areas into several clusters based on combinations of these factors. For each cluster, rooftop area suitability is evaluated at a representative location using the land cover maps, the Open Street Map and specific characteristics of the cluster.&lt;/p&gt;&lt;p&gt;Overall, we present an interdisciplinary approach to integrate technological, social and economic aspects in land cover analysis to estimate PV potentials. While the intricacies may still be insufficient for planning small localized energy systems, this can reasonably benefit energy system modelling from a regional to international scale.&lt;/p&gt;

Historical and Future Land-Cover Change in a Municipality of Ghana

2011 ◽  
Vol 15 (9) ◽  
pp. 1-26 ◽  
Author(s):  
Emmanuel M. Attua ◽  
Joshua B. Fisher
Keyword(s):  
Land Cover ◽  
Land Cover Change ◽  
Land Tenure ◽  
Urban Areas ◽  
Poverty Reduction ◽  
Urban Expansion ◽  
Political Stability ◽  
Land Cover Changes ◽  
Natural Ecosystems ◽  
Land Administration

Abstract Urban land-cover change is increasing dramatically in most developing nations. In Africa and in the New Juaben municipality of Ghana in particular, political stability and active socioeconomic progress has pushed the urban frontier into the countryside at the expense of the natural ecosystems at ever-increasing rates. Using Landsat satellite imagery from 1985 to 2003, the study found that the urban core expanded by 10% and the peri-urban areas expanded by 25% over the period. Projecting forward to 2015, it is expected that urban infrastructure will constitute 70% of the total land area in the municipality. Giving way to urban expansion were losses in open woodlands (19%), tree fallow (9%), croplands (4%), and grass fallow (3%), with further declines expected for 2015. Major drivers of land-cover changes are attributed to demographic changes and past microeconomic policies, particularly the Structural Adjustment Programme (SAP); the Economic Recovery Programme (ERP); and, more recently, the Ghana Poverty Reduction Strategy (GPRS). Pluralistic land administration, complications in the land tenure systems, institutional inefficiencies, and lack of capacity in land administration were also key drivers of land-cover changes in the New Juaben municipality. Policy recommendations are presented to address the associated challenges.

scholarly journals The impact of urbanization expansion on agricultural land in Ethiopia: A review

2020 ◽  
Vol 8 (4) ◽  
pp. 73-80
Author(s):  
Assefa Ayele ◽  
Kassa Tarekegn
Keyword(s):  
Urban Areas ◽  
Agricultural Land ◽  
Urban Expansion ◽  
Rural Livelihoods ◽  
Vital Role ◽  
Rapid Urbanization ◽  
Economic Resource ◽  
House Construction ◽  
Impact Of Urbanization ◽  
The Impact

AbstractIn a country like Ethiopia where the vast majority of the populations are employed in agriculture, land is an important economic resource for the development of rural livelihoods. Agricultural land in peri-urban areas is, however, transformed into built-up regions through horizontal urban expansion that has an effect on land use value. In recent years Ethiopia has been experiencing rapid urbanization, which has led to an ever-increasing demand for land in peri-urban areas for housing and other nonagricultural activities that pervades agricultural land. There is a high demand for informal and illegal peri-urban land which has been held by peri-urban farmers, and this plays a vital role in the unauthorized and sub-standard house construction on agricultural land. This urbanization has not been extensively reviewed and documented. In this review an attempt has been made to assess the impacts of rapid urbanization on agricultural activities. Urban expansion has reduced the areas available for agriculture, which has seriously impacted upon peri-urban farmers that are often left with little or no land to cultivate and which has increased their vulnerability. Housing encroachments have been observed to be uncontrolled due to a weak government response to the trend of unplanned city expansion. This has left peri-urban farmers exposed to the negative shocks of urbanization because significant urbanization-related agricultural land loss has a positive correlation with grain production decrease. Appropriate governing bodies should control urban development in order to control the illegal and informal spread of urbanization on agricultural land that threatens food production.

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