scholarly journals Ground subsidence geo-hazards induced by rapid urbanization: implications from InSAR observation and geological analysis

2012 ◽  
Vol 12 (4) ◽  
pp. 935-942 ◽  
Author(s):  
F. Chen ◽  
H. Lin ◽  
Y. Zhang ◽  
Z. Lu
Keyword(s):  
City Planning ◽  
Anthropogenic Activities ◽  
River System ◽  
Ground Subsidence ◽  
Pearl River Delta Region ◽  
Rapid Urbanization ◽  
Synthetic Aperture Radar Interferometry ◽  
Surface Displacements ◽  
Persistent Scatterer ◽  
Subsidence Monitoring

Abstract. Due to the convenient transportation and construction, cities are prone to be situated in areas with flat terrain and unstable sediments, resulting in the concurrence of ground subsidence and urbanization. Here the interaction between geology, anthropogenic processes and ground subsidence geo-hazards were investigated in the Greater Pearl River Delta region of China. Geological evidences and 2006–2010 persistent scatterer data indicate that anthropogenic activities are dominant, although the distribution of river system and Quaternary sediments are also highly related to significant displacements (primarily at a rate of −15 to 15 mm a−1). The surface displacements derived by synthetic aperture radar interferometry suggest that the urbanization rhythm has to be routinely monitored. Considering analogous urbanization modes, particularly in developing countries, ground subsidence monitoring together with the analysis of its driving force are critical for geo-hazards early-warning, city planning as well as sustainable urbanization.

Application of Differential SAR Interferometry in Mining Subsidence Monitoring

2013 ◽  
Vol 864-867 ◽  
pp. 2735-2738
Author(s):  
Wen Hai Xia ◽  
Yuan Yuan Li
Keyword(s):  
High Spatial Resolution ◽  
Mining Subsidence ◽  
Sar Interferometry ◽  
Sar Images ◽  
Synthetic Aperture Radar Interferometry ◽  
Persistent Scatterer ◽  
Technical Issues ◽  
Subsidence Monitoring ◽  
Differential Sar Interferometry ◽  
Selection Of

Differential synthetic aperture radar Interferometry has been widely applied to monitor mining subsidence for its high spatial resolution, competent accuracy and wide coverage. In this paper, we introduce the principles of InSAR, discuss several key technical issues in mining subsidence monitoring, including selection of SAR images, advanced algorithms for phase unwrapping and Persistent Scatterer InSAR technique.

scholarly journals Ground Subsidence Analysis in Tianjin (China) Based on Sentinel-1A Data Using MT-InSAR Methods

2020 ◽  
Vol 10 (16) ◽  
pp. 5514
Author(s):  
Dong Li ◽  
Xiyong Hou ◽  
Yang Song ◽  
Yuxin Zhang ◽  
Chao Wang
Keyword(s):  
Remote Sensing ◽  
Urban Area ◽  
Control Measures ◽  
Ground Subsidence ◽  
Subsidence Rate ◽  
Persistent Scatterer ◽  
Multi Temporal ◽  
Small Baseline Subset ◽  
Small Baseline ◽  
Subsidence Monitoring

Multi-temporal InSAR (MT-InSAR) methods have been widely used in remote sensing monitoring of ground subsidence, which occurs at many places around the world. Land subsidence, caused by excessive extraction of groundwater, has always been a problem to be solved in Tianjin, China. Although the subsidence in the urban area has been controlled at a low rate, the subsidence issue has not been effectively solved in the suburban area recently, which should be paid much attention. This paper aims to present two multi-temporal differential interferometry techniques, persistent scatterer (PS) and small baseline subset (SBAS), for monitoring the latest surface subsidence in a Tianjin study area on the basis of 20 Sentinel-1A images obtained from March 2017 to March 2019. Our research showed that the average velocity map obtained from the SBAS method closely followed the outcomes of the PS technique from the perspective of identifying similar subsidence patterns. Subsidence rate gradually increased from the urban area of Tianjin to the suburbs and high subsidence zones were mainly distributed at the junction of the Wuqing, Xiqing and Beichen districts. In the past two years, the annual average subsidence rate in the high settlement area mostly exceeded −50 mm/year, which caused serious damage to local infrastructures. Besides, high-resolution remote sensing images combined with field investigations further verified the successful application of MT-InSAR technology in Tianjin’s subsidence monitoring. Effective ground subsidence control measures need to be taken as soon as possible to prevent the situation from getting worse.

scholarly journals Spatiotemporal Dynamics of Nitrogen Budgets under Anthropogenic Activities in Metropolitan Areas

2021 ◽  
Vol 13 (4) ◽  
pp. 2006
Author(s):  
Ning Ding ◽  
Jingfeng Zhu ◽  
Xiao Li ◽  
Xiangrong Wang
Keyword(s):  
Anthropogenic Activities ◽  
River System ◽  
Yangtze River Delta ◽  
Fertilizer Efficiency ◽  
Land Use Pattern ◽  
Human Disturbances ◽  
Nitrogen Budgets ◽  
Metropolitan Regions ◽  
Close Relationship ◽  
Anthropogenic Nitrogen

The rapid growth of metropolitan regions is closely associated with high nitrogen (N) flows, which is known as the most important reason for widespread water pollution. It is, therefore, crucial to explore the spatiotemporal patterns of N budgets under intensive human activity. In this study, we estimated the long-term (2000–2015) N budgets by integrating the net anthropogenic nitrogen input (NANI) and the export coefficient model (ECM) in the Yangtze River Delta Urban Agglomeration (YRDUA), a typical metropolitan area with strong human disturbances. The results revealed that the NANI decreased by 10% from 2000 to 2015, while N exports showed a 6% increase. Hotspots for N budgets were found in the northeastern areas, where cropland and construction land were dominant. The linear regression showed a close relationship between the NANI and N export, and about 18% of the NANI was exported into the river system. By revealing the critical sources and drivers of N budgets over time, our work aimed to provide effective information for regional policy on nitrogen management. Future strategies, such as improving the fertilizer efficiency, optimizing the land use pattern, and controlling the population density, are necessary in order to address the environmental challenge concerns of excessive N.

scholarly journals Spatial-Temporal Evolution of Land Subsidence and Rebound over Xi’an in Western China Revealed by SBAS-InSAR Analysis

2020 ◽  
Vol 12 (22) ◽  
pp. 3756
Author(s):  
Wei Shi ◽  
Guan Chen ◽  
Xingmin Meng ◽  
Wanyu Jiang ◽  
Yan Chong ◽  
...  
Keyword(s):  
Land Subsidence ◽  
Groundwater Level ◽  
Surface Deformation ◽  
Western China ◽  
Ground Subsidence ◽  
Underground Space ◽  
Large Area ◽  
Space Utilization ◽  
Rapid Urbanization ◽  
Ground Fissures

Land subsidence is one of the major urban geological hazards, which seriously restricts the development of many cities in the world. As one of the major cities in China, Xi’an has also been experiencing a large area of land subsidence due to excessive exploitation of groundwater. Since the Heihe Water Transfer Project (HWTP) became fully operational in late 2003, the problem of subsidence has been restrained, but other issues, such as ground rebounds, have appeared, and the effect of the underground space utilization on land subsidence remains unsolved. The spatial-temporal pattern of land subsidence and rebound in Xi’an after HWTP and their possible cause have so far not been well understood. In this study, the evolutionary characteristics of land subsidence and rebound in Xi’an city from 2007–2019 was investigated using Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-SAR) technology to process the Advanced Land Observing Satellite (ALOS) and Sentinel-1A SAR datasets, and their cause and the correlation with groundwater level changes and the underground space utilization were discussed. We found that the land subsidence rate in the study area slowed from 2007–2019, and the subsidence area shrank and gradually developed into three relatively independent and isolated subsidence areas primarily. Significant local rebound deformation up to 22 mm/y commenced in the groundwater recharge region during 2015–2019. The magnitude of local rebound was dominated by the rise in groundwater level due to HWTP, whereas tectonic faults and ground fissures control the range of subsidence and the uplift area. The influence of building load on surface deformation became increasingly evident and primarily manifested by slowing the subsidence reduction trend. Additionally, land subsidence caused by the disturbances during the subway construction period was stronger than that in the operational stage. Future land subsidence in Xi’an is predicted to be alleviated overall, and the areas of rebound deformation will continue increasing for a limited time. However, uneven settlement range may extend to the Qujiang and Xixian New District due to the rapid urban construction. Our results could provide a scientific basis for land subsidence hazard mitigation, underground space planning, and groundwater management in Xi’an or similar regions where severe ground subsidence was induced by rapid urbanization.

scholarly journals Microplastics Determination in the Rivers with Different Urbanisation Variances: A Case Study in Kuching City, Sarawak, Malaysia

2020 ◽  
Vol 10 (2) ◽  
pp. 116-125
Author(s):  
Georgina Johnson ◽  
Wen San Hii ◽  
Samuel Lihan ◽  
Meng Guan Tay
Keyword(s):  
Anthropogenic Activities ◽  
River System ◽  
Anthropogenic Activity ◽  
Domestic Waste ◽  
Shape Identification ◽  
Suburban Areas ◽  
Sampling Locations ◽  
The Relationship ◽  
Main Factor

The presence of microplastics in aquatic systems is mainly due to the anthropogenic activities such as domestic waste dumping. Undeniably, rivers either in urban or suburban areas are always a waste dumpling sites from the surrounding residences. Thus, the purpose of this study was to determine the relationship between microplastic abundance and different degree of urbanization across Kuching in Sarawak. Three sampling locations with different degrees of urbanisation had been studied across Kuching. A total of 137 pieces of microplastics were collected along the study and analysed using stereoscopic microscope for the shape identification and FTIR spectrophotometer for functional groups present in the microplastics. Filament was the most abundant microplastics shape found, whereas the IR results showed that ethylenevinylacetate (9%), polyamides or nylon (15%), polypropylene (42%), poly(methylmethacrylate) (16%) and polystyrene (18%) were found in the study. The most abundant microplastics in the water samples was polypropylene (42%), whereas ethylenevinylacetate (9%) was the least. The degree of urbanisation does not directly relate to the microplastic present in the river system in Kuching City, but the anthropogenic activity is the main factor that affecting the microplastic abundance in the river.   Keywords: anthropologenic activity, FTIR, microplastics, polymer identification, urban, sub-urban

scholarly journals New 30 m resolution Hong Kong climate, vegetation, and topography rasters indicate greater spatial variation than global grids within an urban mosaic

2019 ◽  
Vol 11 (3) ◽  
pp. 1083-1098 ◽  
Author(s):  
Brett Morgan ◽  
Benoit Guénard
Keyword(s):  
Hong Kong ◽  
Precision Agriculture ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
City Planning ◽  
Rapid Urbanization ◽  
Local Climate ◽  
Spatial Understanding ◽  
Environmental And Ecological Studies ◽  
Relevant Variables

Abstract. The recent proliferation of high-quality global gridded environmental datasets has spurred a renaissance of studies in many fields, including biogeography. However, these data, often 1 km at the finest scale available, are too coarse for applications such as precise designation of conservation priority areas and regional species distribution modeling, or purposes outside of biology such as city planning and precision agriculture. Further, these global datasets likely underestimate local climate variations because they do not incorporate locally relevant variables. Here we describe a comprehensive set of 30 m resolution rasters for Hong Kong, a small tropical territory with highly variable terrain where intense anthropogenic disturbance meets a robust protected area system. The data include topographic variables, a Normalized Difference Vegetation Index raster, and interpolated climate variables based on weather station observations. We present validation statistics that convey each climate variable's reliability and compare our results to a widely used global dataset, finding that our models consistently reflect greater climatic variation. To our knowledge, this is the first set of published environmental rasters specific to Hong Kong. We hope this diverse suite of geographic data will facilitate future environmental and ecological studies in this region of the world, where a spatial understanding of rapid urbanization, introduced species pressure, and conservation efforts is critical. The dataset (Morgan and Guénard, 2018) is accessible at https://doi.org/10.6084/m9.figshare.6791276.

scholarly journals Persistent Scatterer Interferometry of Sentinel-1 time series to detect ground subsidence in the city of Recife, Brazil

2020 ◽  
Vol 10 (1) ◽  
pp. 1
Author(s):  
Enton Bedini
Keyword(s):  
Time Series ◽  
Ground Subsidence ◽  
Persistent Scatterer Interferometry ◽  
Persistent Scatterer ◽  
Radar Imagery ◽  
Long Time ◽  
Satellite Radar ◽  
Surrounding Areas ◽  
Satellite Radar Imagery ◽  
The City

Persistent Scatterer Interferometry (PSI) analysis of Sentinel-1 time series was carried out to detect ground subsidence in the city of Recife, Brazil. The dataset consisted of sixty-eight Sentinel-1A Interferometric Wide (IW) Single Look Complex (SLC) images of the time period April 2017 – September 2019. The images were acquired in descending orbit in VV (vertical transmitting, vertical receiving) polarization. The results of the PSI analysis show that in the city of Recife occur several ground subsidence areas. The largest ground subsidence area occurs between the neighborhoods of Afogados, Torrŏes and Cordeiro. The subsidence rates in this area range from few mm/year up to -15 mm/year. This ground subsidence could be a result of groundwater extraction or of subsidence processes in urbanized reclaimed lands. Similar but smaller ground subsidence areas occur in several localities in Recife. In some cases, subsidence with rates of up to -25 mm/year is noted in small zones where new buildings have been constructed in the last decade. This should be due to ground settlement processes, taking a long time due to the particular soils and geology of the locality. This study can serve as a first contribution for further research on the ground subsidence hazard in the city of Recife and the surrounding areas by means of satellite radar imagery.

scholarly journals Effects of land use and water quality on greenhouse gas emissions from an urban river system

2020 ◽  
Author(s):  
Long Ho ◽  
Ruben Jerves-Cobo ◽  
Matti Barthel ◽  
Johan Six ◽  
Samuel Bode ◽  
...  
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Urban Areas ◽  
Anthropogenic Activities ◽  
Ghg Emissions ◽  
Flow Characteristics ◽  
River System ◽  
Urban River ◽  
Polluted Water ◽  
Land Use Types

Abstract. Rivers act as a natural source of greenhouse gases (GHGs) that can be released from the metabolisms of aquatic organisms. Anthropogenic activities can largely alter the chemical composition and microbial communities of rivers, consequently affecting their GHG emissions. To investigate these impacts, we assessed the emissions of CO2, CH4, and N2O from Cuenca urban river system (Ecuador). High variation of the emissions was found among river tributaries that mainly depended on water quality and neighboring landscapes. By using Prati and Oregon Indexes, a clear pattern was observed between water quality and GHG emissions in which the more polluted the sites were, the higher were their emissions. When river water quality deteriorated from acceptable to very heavily polluted, their global warming potential (GWP) increased by ten times. Compared to the average estimated emissions from global streams, rivers with polluted water released almost double the estimated GWP while the proportion increased to ten times for very heavily polluted rivers. Conversely, the GWP of good-water-quality rivers was half of the estimated GWP. Furthermore, surrounding land-use types, i.e. urban, roads, and agriculture, significantly affected the river emissions. The GWP of the sites close to urban areas was four time higher than the GWP of the nature sites while this proportion for the sites close to roads or agricultural areas was triple and double, respectively. Lastly, by applying random forests, we identified dissolved oxygen, ammonium, and flow characteristics as the main important factors to the emissions. Conversely, low impact of organic matter and nitrate concentration suggested a higher role of nitrification than denitrification in producing N2O. These results highlighted the impacts of land-use types on the river emissions via water contamination by sewage discharges and surface runoff. Hence, to estimate of the emissions from global streams, both their quantity and water quality should be included.

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