Technical foundation research on high resolution remote sensing system of China's coastal zone

China's coastal zone is a region with a highly developed economy that contrasts clearly with the slow paced regular investigation on its natural environment,which cannot keep pace with the requirement of economic development and modern management.Laying a theoretical foundation for the modern management of China's costal zone is aimed at. This research focuses on the following processing and analyzing technologies for coastal zone high-resolution remote sensing data: organization and management of large amounts of high-resolution remote sensing data, quick and precise spatial positioning system,algorithms for image fusion in feature level and coastal zone feature extraction. They will form a technical foundation of the system. And, if combined with other research results such as coastal zone remote sensing classification system and its mapping subsystem, an advanced technical frame for remote sensing investigation of coastal zone resource will be constructed.

Construction and implementation of multisource spatial data management system of China's coastal zone and offshore

To meet the increasing demand of national spatial database infrastructure construction and application, a concept model of China's coastal zone scientific data platform is established based on the information feature analysis of a compound dataset, consisting of remote sensing data and conventional data. Based on this concept model, the detailed logical database structure and the storage strategy of remote sensing data and their metadata using ArcSDE are designed. The complicated technology of multisources data combination in this research is crucial to the future coastal zone and offshore database construction and practical running, which will provide intelligent information analysis and technological service for coastal zone and offshore investigation, research, development and management.

Mapping favorable groundwater potential recharge zones using a GIS-based analytical hierarchical process and probability frequency ratio model:A case study from an agro-urban region of Pakistan

In Punjab(Pakistan),the increasing population and expansion of land use for agriculture have severely exploited the regional groundwater resources.Intensive pumping has resulted in a rapid decline in the level of the water table as well as its quality.Better management practices and artificial recharge are needed for the development of sustainable groundwater resources.This study proposes a methodology to delineate favorable groundwater potential recharge zones(FPRI)by integrating maps of groundwater potential recharge index(PRI)with the DRASTIC-based groundwater vulnerability index(VI).In order to evaluate both indexes,different thematic layers corresponding to each index were overlaid in ArcGIS.In the overlay analysis,the weights(for various thematic layers)and rating values(for sub-classes)were allocated based on a review of published literature.Both were then normalized and modified using the analytical hierarchical process(AHP)and a frequency ratio model respectively.After evaluating PRI and FPRI,these maps were validated using the area under the curve(AUC)method.The PRI map indicates that 53%of the area assessed exists in very low to low recharge zones,22%in moderate,and 25%in high to excellent potential recharge zones.The VI map indicates that 38%of the area assessed exists in very low to low vulnerability,33%in moderate,and 29%in high to very high vulnerability zones.The FPRI map shows that the central region of Punjab is moderately-to-highly favorable for recharge due to its low vulnerability and high recharge potential.During the validation process,it was found that the AUC estimated with modified weights and rating values was 79%and 67%,for PRI and VI indexes,respectively.The AUC was less when evaluated using original weights and rating values taken from published literature.Maps of favorable groundwater potential recharge zones are helpful for planning and implementation of wells and hydraulic structures in this region.

Level study on fractal characteristics of tidal creeks and information of seashell habitats in the Gaizhou Beach based on high-resolution satellite images

The fractal characteristics of tidal creeks in the Gaizhou Beach are analyzed based on high-resolution images fusionof Landsat TM and ERS2, and then the graphic models and characteristics of converse information tree of tidalcreeks in the Gaizhou Beach are established. A calculation model is established based on the above results, and at thesame time, quantitative calculation of the evolution characteristics and the diversity between the northern and thesouthern parts of the Gaizhou Beach is carried out. By the supervised classification of these images, distribution andareas of high tidal flats, middle tidal flats and low tidal flats in the Gaizhou Beach are studied quantitatively, and imagecharactistics of seashell habitats in the Gaizhou Beach and the correlation between mudflat distribution and seashellhabitats are studied. At last, the engineering problems in the Gaizhou Beach are discussed.

Construction and implementation of RS integrated application information system of China's coastal zone and offshore

The coastal zone and offshore are clearly of major economic and social importance, in thesame time it causes a series of problems of resources and ecosystem too. The research on and development of integrated application techniques for remote sensing provide not only a microcosmic and dynamic and synchronous technical means to the monitor, but also an integrated technical scheme to harmonically solve the ecological environment problem. The system is designed to focus on the application techniques of multi-sources remote sensing data. By developing remote sensing information extraction module, integrated user platform, and application module objected to the real ocean procedure for China' s coastal zone and offshore, the information system consists of the management of prodigious amount of data, display, analysis, simulation and output will be constructed and implemented. The final objective is to transform the research on ocean remote sensing into application.

Scale effects of the continental coastline of China

Spatial scale is a fundamental problem in Geography. Scale effect caused by fractal characteristic of coastline becomes a common focus of coastal zone managers and researchers. In this study, based on DEM and remote sensing images, multi-scale continental coastlines of China were extracted and the fractal characteristic was analyzed. The results are shown as follows. （1） The continental coastline of China fits the fractal model, and the fractal dimension is 1.195. （2） The scale significant differences according to uplift effects with fractal dimensions of coastline have and subsidence segments along the continental coastlines of China. （3） The fractal dimension of coastline has significant spatial heterogeneity according to the coastline types. The fractal dimension of sandy coastline located in Luanhe River plain is 1.109. The dimension of muddy coastline located in northern Jiangsu Plain is 1.059, while that of rocky coastline along southeastern Fujian is 1.293. （4） The length of rocky coastline is affected by scale more than that of muddy and sandy coastline. Since coastline is the conjunction of sea, land and air surface, the study of coastline scale effect is one of the scientific bases for the researches on air-sea-land interaction in multi-scales.

Geological and surfacial processes and major disaster effects in the Yellow River Basin

The Yellow River Basin(YRB) is characterized by active geological and tectonic processes, rapid geomorphological evolution, and distinct climatic diversity. Correspondingly, major disasters in the YRB are characterized by varied types,extensive distributions, and sudden occurrences. In addition, major disasters in the YRB usually evolve into disaster chains that cause severe consequences. Therefore, major disasters in the YRB destroy ecologies and environments and influence geological and ecological safety in the basin. This paper systematically reviews research on geological and surface processes, major disaster effects, and risk mitigation in the YRB, discusses the trends and challenges of relevant research, analyzes the key scientific problems that need to be solved, and suggests prospects for future research based on the earth system science concept. Themes of research that should be focused on include geological, surface and climatic processes in the YRB and their interlinking disaster gestation mechanisms;formation mechanisms and disaster chain evolutions of giant landslides in the upper reach of the YRB;mechanisms and disaster chain effects of loess water-soil disasters in the middle reach of the YRB;occurrence patterns and amplifying effects of giant flood chains in the lower reach of the YRB;and risk mitigations of major disasters in the YRB. Key scientific problems that need to be solved are as follows: how to reveal the geological, surface and climatic processes that are coupled and interlinked with gestation mechanisms of major disasters;how to clarify the mutual feedback effects between major disasters and ecology;and how to develop a human-environmental harmony-based integrated risk mitigation system for major disasters. Prospects for future studies that follow the earth system science concept include the following: highlighting interdisciplinary research to reveal the interlinked disaster gestation mechanisms of the geology, surface and climate in the YRB in the past, present, and future;forming theories to clarify the regional patterns, dynamic mechanisms, and mutual-feedback effects between disaster chains and ecology in the YRB on land and in rivers in the region;solving technological bottlenecks to develop assessment models and mitigation theories for integrated risks in the YRB by following the human-environment harmony concept;and finally, establishing a demonstratable application pattern characterized by "whole-basin coverage" and "zonal controls", thereby guaranteeing ecological and geological safety in the basin and providing scientific support for ecological conservation and high-quality development of the YRB.

Estimation of daily PM2.5 concentration and its relationship with meteorological conditions in Beijing

When investigating the impact of air pollution on health, particulate matter less than 2.5μm in aerodynamic diameter （PM2.5） is considered more harrnful than particulates of other sizes. Therefore, studies of PM2.5 have attracted more attention. Beijing, the capital of China, is notorious for its serious air pollution problem, an issue which has been of great concern to the residents, government, and related institutes for decades. However, in China, significantly less time has been devoted to observing PM2.5 than for PM10. Especially before 2013, the density of the PM2.5 ground observation network was relatively low, and the distribution of observation stations was uneven. One solution is to estimate PM2.5 concentrations from the existing data on PM10. In the present study, by analyzing the relationship between the concentrations of PM2.5 and PM10, and the meteorological conditions for each season in Beijing from 2008 to 2014, a U-shaped relationship was found between the daily maximum wind speed and the daily PM concentration, including both PM2.5 and PM10. That is, the relationship between wind speed and PM concentration is not a simple positive or negative correlation in these wind directions; their relationship has a complex effect, with higher PM at low and high wind than for moderate winds. Additionally, in contrast to previous studies, we found that the PM2.5/PM10 ratio is proportional to the mean relative humidity （MRH）. According to this relationship, for each season we established a multiple nonlinear regression （MNLR） model to estimate the PM2.5 concentrations of the missing periods.

Determinants and identification of the northern boundary of China's tropical zone

The influence of monsoon climatic characteristics makes the tropics of China different from those of other parts of the world. Therefore, the location of the northern boundary of China's tropical zone has been one of the most controversial issues in the study of comprehensive physical regionalisation in China. This paper introduces developments in the study of the northern boundary of China's tropical zone, in which different scholars delimit the boundary with great differences based on different regionalisation objectives, indexes, and methods. The main divergence of opinion is found in different understandings of zonal vegetation, agricultural vegetation type, cropping systems, tropical soil type and tropical characteristics. In this study, we applied the Geo Detector model, which measures the spatial stratified heterogeneity, to validate the northern boundaries of the tropical zone delimited by six principal scholars. The results show that the mean q-statistic value of the higher latitude boundary delimited by Ren Mei'e is the largest(q=0.37), suggesting that, of the rival views, it best reflects the regional differences between China's tropical and subtropical zones, but it is not necessarily suitable for guiding the development of tropical agriculture. The mean values of the q-statistics of Zheng Du's line and Yu Xianfang's line around the Leizhou Peninsula at a lower latitude were smaller, at 0.10 and 0.08 respectively, indicating that the regional differences were smaller than those of Ren Mei'e's boundary. Against the background of global climate change, the climate itself is changing in fluctuation. It is, thus, worth our further research whether the northern boundary of the tropical zone should not be a fixed line but rather should fluctuate within a certain scope to reflect these changes.

Correspondence:Unified characterization of hydro-mechanical properties of soil-bentonite mixtures exposed to pore-fluid salinity

1 Introduction Knowledge on the impact of pore-fluid salinity,characterized by the changes of pH,ionic concentration,material composition,and other factors,on geotechnical engineering applications involving hydro-chemo-mechanical systems,is expanding.

Seasonal dynamic pattern analysis on global FPAR derived from AVHRR GIMMS NDVI

The purpose of this paper is to develop Advanced Very High Resolution Radiometer(AVHRR)Global Inventory Modelling and Mapping Studies(GIMMS)Normalised Difference Vegetation Index(NDVI;AVHRR GIMMS NDVI for short)based fraction of absorbed photosynthetically active radiation(FPAR)from 1982 to 2006 and focus on their seasonal and spatial patterns analysis.The available relationship between FPAR and NDVI was used to calculate FPAR values from 1982 to 2006 and validated by Moderate-resolution Imaging Spectroradiometer(MODIS)FPAR product.Then,the seasonal dynamic patterns were analysed,as well as the driving force of climatic factors.Results showed that there was an agreement between FPAR values from this study and those of the MODIS product in seasonal dynamic,and the spatial patterns of FPARvary with vegetation type distribution and seasonal cycles.The time series of average FPAR revealed a strong seasonal variation,regular periodic variations from January 1982 to December 2006,and opposite patterns between the Northern and Southern Hemispheres.Evergreen vegetation FPARvalues were close to 0.7.A clear single-peak curve was observed between 308N and 808N?an area covered by deciduous vegetation.In the Southern Hemisphere,the time series fluctuations of FPAR averaged by 0.78 latitude zones were not clear compared to those in the Northern Hemisphere.A significant positive correlation(PB0.01)was observed between the seasonal variation of temperature and precipitation and FPAR over most other global meteorological sites.

An index-based spatial evaluation model of exploitative intensity: A case study of coastal zone in Vietnam

Coastal zones play a major role in the conservation of marine ecosystems and the sustainable use of resources not only because of their special geographical environment but also because of their high temporal and spatial variability. With the development of urbaniza- tion, the exploitation and utilization of coasts have become important issues in the debate. To evaluate variations in the intensity of the land resource exploitation of coastal zones, an in- dex-based model has been proposed in this paper, and coastal Vietnam has been established as the study area. The model is based on four normalized indexes to realize rapid evaluation of the spatial distribution of the exploitative intensity after zoning. The model was established to characterize the different exploitative intensities in different segments of the coast and to graphically present a sequence of decision choices for decision-makers. The results are as follows. （1） The simplicity and rapidity of the index operations can address the fast-changing characteristics of coastal exploitation and meet the desired precision. （2） The choices of the landward buffers fit well with the banded characteristics of the coastal zone. The buffers are horizontally divided into equidistant subregions, which can quantify the spatial differentiation of the exploitative intensity along the coast and perpendicular to the coast. （3） The average exploitative intensity is low, and the proportion of area that is to be exploited accounts for approximately 50%.Considering its spatial variation from north to south, the land exploitative intensity in the north is higher than that in the south. Compared to the intensity of land re- source exploitation in the 20 km and 10 km buffers, the land exploitative intensity in the 5 km buffer is higher. The state of the intensity of land resource exploitation and how it can be used by stakeholders to manage coastal resources are then discussed.

Long-Term Variation of Global GEOV2 and MODIS Leaf Area Index (LAI) and Their Uncertainties: An Insight into the Product Stabilities

Leaf area index(LAI)is an essential climate variable that is crucial to understand the global vegetation change.Long-term satellite LAI products have been applied in many global vegetation change studies.However,these LAI products contain various uncertainties that are not been fully considered in current studies.The objective of this study is to explore the uncertainties in the global LAI products and the uncertainty variations.Two global LAI datasets—the European Geoland2 Version 2(GEOV2)and Moderate Resolution Imaging Spectroradiometer(MODIS)(2003-2019)—were investigated.The qualitative quality flags(QQFs)and quantitative quality indicators(QQIs)embedded in the product quality layers were analyzed to identify the temporal anomalies in the quality profile.The results show that the global GEOV2(0.042/10a)and MODIS(0.034/10a)LAI values have steadly increased from 2003 to 2019.The global LAI uncertainty(0.016/10a)and relative uncertainty(0.3%/10a)from GEOV2 have also increased gradually,especially during the growing season from April to October.The uncertainty increase is larger for woody biomes than for herbaceous types.Contrastingly,the MODIS LAI product uncertainty remained stable over the study period.The uncertainty increase indicated by GEOV2 is partly attributed to the sensor shift in the product series.Further algorithm enhancement is necessary to improve the cross-sensor performance.This study highlights the importance of studying the LAI uncertainty and the uncertainty variation.Temporal variations in the LAI products and the product quality revealed herein have significant implications on global vegetation change studies.

Novel approaches to the multiscalar display of vector data

There are many challenges to achieving quality multiscalar displays of vector data in geographical information system(GIS).Acknowledging and making use of the differences between traditional cartographic generalization and multiscalar display in GIS,this paper focuses on novel approaches to the definition of small objects and the establishment of scale sequence.The ease of implementation and efficacy of the solutions proposed are exemplified and analyzed.Possibilities for further research into the multiscalar display of vector data in GIS are thereby suggested.

A Bibliometric Visualization Review of the MODIS LAI/FPAR Products from 1995 to 2020

The MODIS LAI/FPAR products have been widely used in various fields since their first public release in 2000.This review intends to summarize the history,development trends,scientific collaborations,disciplines involved,and research hotspots of these products.Its aim is to intrigue researchers and stimulate new research direction.Based on literature data from the Web of Science(WOS)and associated funding information,we conducted a bibliometric visualization review of the MODIS LAI/FPAR products from 1995 to 2020 using bibliometric and social network analysis(SNA)methods.We drew the following conclusions:(1)research based on the MODIS LAI/FPAR shows an upward trend with a multiyear average growth rate of 24.9%in the number of publications.(2)Researchers from China and the USA are the backbone of this research area,among which the Chinese Academy of Sciences(CAS)is the core research institution.(3)Research based on the MODIS LAI/FPAR covers a wide range of disciplines but mainly focus on environmental science and ecology.(4)Ecology,crop production estimation,algorithm improvement,and validation are the hotspots of these studies.(5)Broadening the research field,improving the algorithms,and overcoming existing difficulties in heterogeneous surface,scale effects,and complex terrains will be the trend of future research.Our work provides a clear view of the development of the MODIS LAI/FPAR products and valuable information for scholars to broaden their research fields.