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Modeling spatial-temporal variability of PM2.5 concentrations in Belt and Road Initiative (BRI) region via functional adaptive density approach

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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 2023年第51期30卷 110931-110955页

作者： Hael, Mohanned Abduljabbar Jiangxi Univ Finance & Econ Sch Stat & Data Sci Nanchang 330013 Peoples R China Taiz Univ Dept Data Sci & Informat Technol Taizi 9674 Yemen

The rapid development of the Belt and Road Initiative (BRI) has led to severe air pollution dominated by PM2.5 concentrations which can cause a profound negative impact on human health and economic activity. This problem poses a critical environmental challenge to efficiently handling large-scale spatial-temporal PM2.5 data in this extended region. Functional data analysis (FDA) technique offers powerful tools that have the potential to enhance the analysis of spatial distributions and temporal dynamic changes in high-dimensional pollution data. However, modeling the spatial-temporal variability of PM2.5 concentrations by FDA remains unrevealed in the BRI region. To address this research gap, our study aimed to achieve two main objectives: first, to model the spatial-temporal dynamic variability of PM2.5 in 125 BRI nations (1998-2021), and second, to identify the underlying clusters behind the variations. We employed the recently developed functional adaptive density peak (FADP) clustering approach to solve the current problem. The proposed method is based on the joint use of functional principal components (FPCs) and functional cluster analyses. The main results are as follows: (i) The first three FPCs almost captured 99% of the total variations involving all valuable information on PM2.5 concentrations. (ii) PM2.5 pollution was highly concentrated in the developing countries (Pakistan, Bangladesh, and Nigeria) and the developed countries (Arabian Gulf countries: Qatar, United Arab Emirates, Bahrain, Saudi Arabia, Oman), and the least developed countries (Yemen and Chad). (iii) Three optimal clusters were identified and thus classified the PM2.5 into three distinct degrees of pollution: severe, moderate, and light. (iv) Cluster 1 had a severe pollution effect degree with a high rate of change, and it covered the Arabian Peninsula countries, African countries (Cameroon, Egypt, Gambia, Mali, Mauritania, Nigeria, Sudan, Senegal, Chad), Bangladesh, and Pakistan. (v) Ab

关键词： Functional data analysis (FDA) Functional adaptive density peak (FADP) clustering Functional principal components analysis (FPCA) PM2.5 pollution spatial-temporal variability Belt and Road Initiative (BRI)

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Simulated Investigation on the Impact of spatial-temporal variability of Rainstorms on Flash Flood Discharge Process in Small Watershed

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WATER RESOURCES MANAGEMENT 2023年第3期37卷 995-1011页

作者： Chen, Guangzhao Hou, Jingming Hu, Yuan Wang, Tian Yang, Shaoxiong Gao, Xujun Xian Univ Technol State Key Lab Ecohydraul Northwest Arid Reg Xian 710048 Shaanxi Peoples R China China Power Construct Grp Co LTD Northwest Eng Corp Ltd Xian 710065 Shaanxi Peoples R China

With the spatial-temporal variability of rainstorms becoming more diversified, it is urgent to summarize how the spatial-temporal variability of rainstorm affects the flash flood discharge process and to explore its internal mechanism. This work proposes a research framework based on the rainstorm spatial-temporal structure design method and the quantitative analysis of flash flood discharge process modeling. This framework generates rainstorm data with different spatial-temporal variability through the rainstorm spatial-temporal structure design method, and further simulates discharge process under different rainstorm scenarios through the hydrodynamic model. Based on the analysis of simulated results, the error correction coefficient is generated to improve the accuracy of simulation. In this study, the Baogaisi watershed was used for simulation. The results show that when the rainstorm center is at the upstream watershed, the peak discharge increases, and the flood peak time is advanced because of the transformation of gravitational potential energy into kinetic energy. When the rainstorm center is fixed at a position, the total flood volume and the peak discharge are about 2 similar to 10 times that of uniform spatial distributed scenario, the flood peak time can be advanced to 55 min. In the mobile rainstorm, the peak discharge and the total flood volume are significantly reduced and the flood peak time is lagged, the flood peak discharge can be reduced by up to 30% of the uniform spatial distributed scenario. Strengthening the understanding of the impact can help to improve the accuracy of discharge process simulation.

关键词： Flash flood spatial-temporal variability Rainstorm Discharge process Numerical simulation

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A novel irrigation canal scheduling model adaptable to the spatial-temporal variability of water conveyance loss

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AGRICULTURAL WATER MANAGEMENT 2022年第0期274卷

作者： Liao, Xiangcheng Mahmoud, Ali Hu, Tiesong Wang, Jinglin Wuhan Univ State Key Lab Water Resources & Hydropower Engn Sc Wuhan 430072 Peoples R China Hubei Water Resources Res Inst Wuhan 430070 Peoples R China Hubei Prov Water Saving Res Ctr Wuhan 430070 Peoples R China

The water conveyance loss of irrigation canals shows significant spatial-temporal variability both along the canal reach and over time. An accurate representation of these variances in irrigation canal scheduling is essential to reduce water conveyance loss. However, the existing optimal irrigation scheduling models (OISMs) still have deficiencies in dealing with spatial-temporal variability of water conveyance losses, which seriously limits the model performance in many irrigation areas with high spatial-temporal variability. Borrowing a concept from hydrology, we propose a Dynamic Calculation Method of canal water conveyance loss (DMWCL), in which antecedent water conveyance index (AWCI) is defined to represent the effects of antecedent soil water content upon infiltration losses, and the integral-flow balance method is adopted to describe the characteristics of canal discharge decreasing along the canal reach. Based on the DMWCL, we present a novel canal scheduling model with the potential to adapt to spatial-temporal variability (DMWCL-CS). The new model is applied to the Hetao Irrigation District, Inner Mongolia, a typical agricultural watershed in China. Our results across the case studies show that the canal water delivery schedule derived by the DMWCL-CS model reduces water conveyance loss and improves irrigation performance, ranging from 2.49 million m3 to 10.60 million m3 in 2014 and from 0.60 million m3 to 6.17 million m3 in 2016, respectively, compared to that of three additional models. Interestingly, we find that the water delivery schedule of the DMWCL-CS model accelerates the wetting process of the canal bed soil to reduce the water conveyance loss and increases the discharge to adapt to the characteristics that the discharge decreases along the canal reach. The DMWCL-CS model provides essential insights for irrigation managers to formulate a canal water delivery schedule that adapts to spatial-temporal variability. The proposed framework is generic

关键词： Irrigation canal scheduling Canal water conveyance loss spatial-temporal variability Dynamic calculation method Antecedent water conveyance index

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Assessment of spatial and temporal variability of groundwater level in the aquifer system on the flanks of Mount Meru, Northern Tanzania

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JOURNAL OF HYDROLOGY-REGIONAL STUDIES 2022年 44卷

作者： Bennett, George Van Camp, Marc Shemsanga, Ceven Kervyn, Matthieu Walraevens, Kristine Univ Ghent Dept Geol Lab Appl Geol & Hydrogeol Ghent Belgium Univ Dodoma Dept Min & Mineral Proc Engn Dodoma Tanzania Univ Dodoma Dept Geol Dodoma Tanzania Vrije Univ Brussel Dept Geog Phys Geog Brussels Belgium

Study region: Mount Meru located in Northern *** focus: Groundwater level monitoring is essential for uncovering the spatial-temporal variation of groundwater levels in a studied aquifer, helping discussions on the sustainable use and management of groundwater resources. This study analyses the spatial and temporal variability of groundwater level in the shallow aquifer system on the flanks of Mount Meru. Time series analysis of groundwater level measurements obtained in two hydrologic years: 2018-2019 and 2019-2020 is *** hydrological insights for the region: On the north-eastern flank of Mount Meru, at Ngarenanyuki, there is a rise of about 1.80 m between the static water levels in April 2018 and December 2020 in the shallow aquifer, whereas on the western flank, at Mamsa, there is a decrease of about 0.50 m between the static water levels in May 2018 and December 2020 in the shallow aquifer, this can be attributed to low/reduced recharge (due to very low hydraulic conductivity and semi-confined condition of the aquifer), or exploitation. Hence, the current pumping practices in the aquifer on the western flank should be restrained for sustainable groundwater management.

关键词： Groundwater level assessment spatial-temporal variability Piezometric map Groundwater level fluctuation Mount Meru Tanzania

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spatial–temporal variability of terrestrial vegetation productivity in the Yangtze River Basin during 2000–2009

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Journal of Plant Ecology 2014年第1期7卷 10-23页

作者： Yulong Zhang Conghe Song Kerong Zhang Xiaoli Cheng Quanfa Zhang Key Laboratory of Aquatic Botany and Watershed Ecology Wuhan Botanical GardenChinese Academy of Sciences1 Moshan RoadWuhan 430074China Department of Geography University of North Carolina209 South RoadChapel HillNC 27599USA Department of Life Science University of the Chinese Academy of Sciences19 Yuquan RoadBeijing 100049China School of Forestry and Landscape Architecture Anhui Agricultural University130 West Changjiang RoadHefeiAnhui 230026China

Aims Terrestrial net primary production(NPP),the balance of gross primary production(GPP)and autotrophic respiration(AR),is a critical measure of carbon sequestration capacity for the Earth’s land *** aim of this study was to understand the spatio-temporal variability of NPP associated with GPP and AR in the Yangtze River Basin(YRB),China,from 2000 to 2009 during which the basin warmed *** We first derived AR and carbon-use efficiency(CUE)from the improved Moderate Resolution Imaging Spectroradiometer GPP/NPP products(MOD17)and then conducted spatial analysis to quantify how NPP relates to GPP,AR and their relationship with key observed climate variables(temperature,precipitation and sunshine percentage)in the YRB during 2000–*** Findings The spatial pattern of NPP in the YRB was predominantly determined by GPP and further modified by *** GPP and relatively low AR made the southern Jinshajiang sub-basin the most productive area in NPP in the YRB.A large portion of the YRB experienced a warmer and drier climate trend in the growing season during 2000–*** the upper reaches of the basin,possessing a relatively low temperature base,increases in temperature led to greater increases in GPP than those in AR,resulting in greater increased ***,in the middle and lower reaches of the basin where the base temperature is relatively high,increases in temperature led to greater increases in AR than those in GPP,leading to decreases in ***,86.7%of the vegetated area showed a consistent GPP and NPP trend through time with 71.3%of the vegetated area having a positive trend both in GPP and NPP,and the remaining 13.3%of vegetated areas showed an opposite trend in GPP and NPP,with positive GPP and negative NPP trajectories dominating(10.1%of vegetated area)the *** climate warming generally had positive effects on vegetation growth in most areas of the basin,areas with increased NPP(74.5%)were less extensive than t

关键词： Yangtze River Basin climate warming GPP AR NPP CUE spatial-temporal variability

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spatial-temporal variability of Coastline in Bohai Rim Based on Fractal Dimension 11

Spatial-temporal Variability of Coastline in Bohai Rim Based...

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Conference on Remote Sensing and Modeling of Ecosystems for Sustainability XI

作者： Xu, Ning Gao, Zhiqiang Ning, Jicai Liu, Xiangyang Chinese Acad Sci Yantai Inst Coastal Zone Res Yantai 264003 Peoples R China

ISBN: (纸本)9781628412482

This paper extracted the spatial distribution of the continental coastline of Bohai Rim utilizing Remote Sensing and GIS spatial analysis techniques, and calculated the fractal dimension of the coastline by box-counting method, with a time from 1990 to 2010. Moreover, we analyzed the characteristics of spatial-temporal variability of the coastline's length and fractal dimension, the relationship between the large scales length change and fractal dimension change. During the research period, the coastline length of the study area increased progressively and the most significant change in coastline length was found in Tianjin Municipality. Especially after 2000, the coastline length entered a period of rapid growth. In addition, the fractal dimension of the overall coastline of the study area was between the fractal dimensions of the regional coastlines and was close to the maximum fractal dimensions of these regional coastlines. The fractal dimension of the coastline in Bohai Rim was increasing during the research period, large scale project such as ports construction, reduced tortuous degree of the coastline.

关键词： Coastline Remote sensing Fractal dimension spatial-temporal variability Bohai Rim

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A New Modified Tennant Method with spatial-temporal variability

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WATER RESOURCES MANAGEMENT 2014年第14期28卷 4911-4926页

作者： Li, Changwen Kang, Ling Huazhong Univ Sci & Technol Coll Hydropower & Informat Engn Wuhan 430074 Peoples R China

Tennant method gets more widely applied worldwide via diverse modified forms, yet the spatial-temporal variability of ecological flow (EF) criteria has frequently been questioned, because the EF criteria are based on constant percentages of average periodic flow. To solve this problem, a modified Tennant method with EF criteria changing with flow regime is proposed in this research. The improved approach consists of four steps: (1) monthly and year-to-year flow variability considered, natural daily flow series are grouped into 12 monthly categories, and every category is subdivided into wet, normal and dry year groups;(2) taken the influence of extreme inter-annual flow events and uneven intra-annual distribution on average periodic flow into account, the median daily flow for every month and water year is taken as the ceiling of optimum EF;(3) spatial flow variability considered, the daily average streamflow with 90 % exceeding probability in monthly flow duration curves is taken as the lower limit of minimum EF;(4) the EF criteria from minimum to optimum are designed by using the idea of arithmetic progression from Tennant method, and the classification number is appropriately readjusted. Finally, to verify the rationality of the improved method, the EFs of a large river (Hanjiang River), a middle river (Meijiang River) and a small river (Panlonghe River) with different flow regimes are assessed and compared with common hydrological methods. The results show that the proposed approach is rational and has excellent monthly and inter-annual rich-poor variability and transferability in different riverine ecosystems.

关键词： Ecological flow Modified Tennant method spatial-temporal variability Flow duration curve

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variability of greenhouse gases in Lagos: CO2, CH4, N2O and halocarbons in a developing Western Africa megacity

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URBAN CLIMATE 2025年 60卷

作者： Odu-Onikosi, Adebola Oke, Ganiyu Hopke, Philip K. Solomon, Paul A. Clarkson Univ Inst Sustainable Environm Potsdam NY 13699 USA EnvironQuest Ltd 23a Mamman Kontagora House Lagos Nigeria Univ Rochester Sch Med & Dent Dept Publ Hlth Sci Rochester NY 14642 USA PAS Environm LLC Henderson NV 89052 USA

Greenhouse gas (GHG) emissions significantly affect climate change, public health, and the environment. Lagos, a developing megacity with a bustling economy and growing population, contributes substantially to GHG concentrations through intensive energy consumption and material use. This study investigated the temporal and spatial distributions of key ambient GHGs across Lagos, Nigeria, from August 2020 to July 2021, including carbon dioxide (COQ), nitrous oxide (NQO), methane (CH4), and halocarbons (chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons). Using data from a network of six sampling stations, the relationships among these GHGs and their concentrations in relation to urban emissions were analyzed. Our findings identified distinct seasonal variability in GHG concentrations driven by urban activities and meteorological conditions. COQ concentrations ranged from 455 to 484 ppmv, with peak values at the IKO and NCF stations. CH4 concentrations reached a maximum of 2210 ppbv, primarily attributed to waste management activities, while NQO showed minimal variations suggesting limited local sources. Halocarbon concentrations peaked during the dry season due to increased air conditioning use and industrial activities. Alternatively, COQ, NQO, and CH4 were highest during the wet season (April to July), influenced by increased vehicular emissions and enhanced waste decomposition in waterlogged landfills. The study identified transportation, waste management, and refrigeration as the primary GHG sources in Lagos. The observed correlations between halocarbons and other GHGs underscore the interconnected nature of urban emissions sources. These findings provide valuable insights for policymakers and stakeholders to develop targeted mitigation strategies for reducing GHG emissions in rapidly urbanizing megacities.

关键词： GHGs Gaseous pollutants Halocarbons spatial-temporal variability Seasonality Wind patterns

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Spatiotemporal variability of event-based rainstorm: The perspective of rainfall pattern and concentration

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INTERNATIONAL JOURNAL OF CLIMATOLOGY 2022年第12期42卷 6258-6276页

作者： He, Sijing Wang, Zhaoli Wang, Dagang Liao, Weilin Wu, Xushu Lai, Chengguang South China Univ Technol State Key Lab Subtrop Bldg Sci Sch Civil Engn & Transportat Guangzhou 510641 Peoples R China Sun Yat Sen Univ Sch Geog & Planning Guangzhou Peoples R China South China Univ Technol Guangdong Engn Technol Res Ctr Safety & Greenizat Guangzhou Peoples R China

Rainfall pattern (RP) and precipitation concentration (PC) are two critical indices for measuring rainfall. Detecting their changes under global warming helps to understand better the rainfall variability and the flooding formation. Using the Guangdong Province, China, as a study case, five criteria were used to determine the independent precipitation events for hourly precipitation data from 1967 to 2012. The RP and PC of the events were identified, and then, their spatiotemporal variability was investigated further. The results show that (a) the occurrence frequency during 46 years, average rainfall amount and duration of independent rainfall in the coastal areas were higher than in other regions. (b) The dominant RPs in Guangdong are unimodal (more than 70%), especially the pattern with early peak (mode I;39.5%);however, the number of stations with mode I as dominant RP decreased over time, while those with mode III (the pattern with late peak) increased. (c) Precipitation concentration index can be used for measuring the concentration of independent rainfall events, and its fixed minimum inter-event time has significant impacts on RP and PC. The PC of the events with early peak is higher, and the concentration in the west is generally higher than those in the east under different RPs.

关键词： Guangdong Province independent rainfall precipitation concentration rainfall pattern spatial-temporal variability

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Rockfall Magnitude-Frequency Relationship Based on Multi-Source Data from Monitoring and Inventory

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REMOTE SENSING 2023年第8期15卷 1981-1981页

作者： Janeras, Marc Lantada, Nieves Nunez-Andres, M. Amparo Hantz, Didier Pedraza, Oriol Cornejo, Rocio Guinau, Marta Garcia-Selles, David Blanco, Laura Gili, Josep A. Palau, Joan Inst Cartograf & Geol Catalunya ICGC Barcelona 08038 Spain Univ Politecn Catalunya BarcelonaTech Dept Civil & Environm Engn Barcelona 08034 Spain Univ Grenoble Alpes Univ Gustave Eiffel Univ Savoie Mont Blanc CNRSIRDISTerre F-38000 Grenoble France Univ Barcelona UB Dept Dinam Terra & Ocea GRC RISKNAT UB GeomodelsFac Ciencies Terra Barcelona 08028 Spain

Quantitative hazard analysis of rockfalls is a fundamental tool for sustainable risk management, even more so in places where the preservation of natural heritage and people's safety must find the right balance. The first step consists in determining the magnitude-frequency relationship, which corresponds to the apparently simple question: how big and how often will a rockfall be detached from anywhere in the cliff? However, there is usually only scarce data on past activity from which to derive a quantitative answer. Methods are proposed to optimize the exploitation of multi-source inventories, introducing sampling extent as a main attribute for the analysis. This work explores the maximum possible synergy between data sources as different as traditional inventories of observed events and current remote sensing techniques. Both information sources may converge, providing complementary results in the magnitude-frequency relationship, taking advantage of each strength that overcomes the correspondent weakness. Results allow characterizing rockfall detachment hazardous conditions and reveal many of the underlying conditioning factors, which are analyzed in this paper. High variability of the hazard over time and space has been found, with strong dependencies on influential external factors. Therefore, it will be necessary to give the appropriate reading to the magnitude-frequency scenarios, depending on the application of risk management tools (e.g., hazard zoning, quantitative risk analysis, or actions that bring us closer to its forecast). In this sense, some criteria and proxies for hazard assessment are proposed in the paper.

关键词： rockfall hazard detection and observation TLS monitoring inventory magnitude-frequency multi-scale multi-source spatial-temporal variability conglomerate basalt

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