VIETNAM JOURNAL OF EARTH SCIENCES最新文献

{"title":"Investigation and prediction of noise pollution levels from wind turbines: A case study of Nexif Energy Ben Tre wind power plant, South Vietnam","authors":"Huan Nguyen Quoc, Cuong Tran Thien, Cu Nguyen Xuan, T. V. Dinh, Minh Tran, Liem Ngo Van","doi":"10.15625/2615-9783/16443","DOIUrl":"https://doi.org/10.15625/2615-9783/16443","url":null,"abstract":"In recent years, the demand for electric power in Vietnam has increased at annual growth rates of 10% to 12%, and the challenge is to promote renewable energy sector. One of these sustainable energy sources is to harness energy from the wind through wind turbines (WTs). In fact, more wind power plants in Vietnam are continuously to be built due to the rapidly growing demand of country's industrialization and modernization process. However, a significant hindrance preventing the widespread use of WTs in Vietnam is the noise they produce, which significantly contributes to the annoyance experienced by residents living near wind farms. The prediction of noise impacts for new wind farms is one of the many aspects of the environmental impact assessment process in Vietnam as well as in the world. In addition, the determination of the 45 dBA noise contour-line is very important because it is the basis for determining the scope of the project impact according to the IFC/WB performance standards and the number of households to be relocated from the project site. The article’s main focus is therefore on the estimation and simulation of the acoustical noise produced by 18 WTs during the operation phase of Nexif Energy Ben Tre wind power plant and the background noise levels at the project site have been performed by using a combination of specific study methods such as environmental modeling (iNoise Pro modeling software), mapping and geographic information systems. The obtained results show the importance of using modeling method in quantifying the noise levels generated from 18 wind turbines of the Nexif Energy Ben Tre wind power plant met IFC standard and Vietnamese regulation on noise during day-time, but did not meet IFC standard on noise during night-time. The level of background noise measured during night-time in the project area also did not meet IFC standard. Therefore, the overall cumulative noise level exceeds the IFC standard for residential area (45 dBA only). In addition, the appropriate solutions to reduce noise levels from WTs are also proposed.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49233309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A numerical investigation of the impact of shield machine’s operation parameters on the settlements above twin stacked tunnels - A case study of Ho Chi Minh urban railway Line 1","authors":"Anh Do Ngoc, D. Dias, Thang Trong Dang","doi":"10.15625/2615-9783/16442","DOIUrl":"https://doi.org/10.15625/2615-9783/16442","url":null,"abstract":"Three-dimensional finite difference calculations are proposed to investigate the influence of operation parameters of the shield machines during twin stacked tunnel excavation on the surface settlements. The numerical model is validated by experimental data obtained from Hochiminh’s metro line 1 project, used as a reference case in this study. The parametric study focuses on the influence of the face support pressure, the grouting pressure, and the shield’s length. The numerical results indicated that a decrease does not always follow an increase in surface settlements' face and grouting pressure. A shorter shield machine causes smaller surface settlements to develop over single lower and twin stacked tunnels.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43113262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance evaluation of Auto-Regressive Integrated Moving Average models for forecasting saltwater intrusion into Mekong river estuaries of Vietnam","authors":"T. T. Thanh, Liem Nguyen Duy, Luu Pham Thanh, Y. My, Yen Tran Thi Hoang, Quang Ngo Xuan, Tan Lam Van, Hoai Pham Ngoc","doi":"10.15625/2615-9783/16440","DOIUrl":"https://doi.org/10.15625/2615-9783/16440","url":null,"abstract":"The Mekong Delta is the most severely affected area by saltwater intrusion in Vietnam. Recent studies have focused on predicting this disaster with weekly and decade lead times without many seasonal forecasts, which is important for planning crop selection, crop structure, and sowing time. This study aims to forecast the spatial distribution of saltwater intrusion into the Mekong river estuaries of Vietnam during the dry season of 2021 by integrating Auto-Regressive Integrated Moving Average with Geographic Information System. ARIMA models were trained with a single input of water salinity measurements from 2012 to 2020. Compared to the weekly salinity observations in 2021, these models predicted very well in the My Tho and Ham Luong rivers but unsatisfactory performance in the Co Chien river. The deepest saltwater intrusion will occur between March 19th and April 16th of 2021, when the 4‰ saline front will move the farthest distance of 41,41 and 44 kilometers inland from the sea through My Tho, Ham Luong Co Chien rivers, respectively. The entire river system will be exposed to moderate risk of saltwater intrusion. Freshwater zones decreased significantly to 0.73% of the whole area of Ben Tre province. These findings could provide a valuable scientific foundation for the appropriate management of coastal aquifers to control or reduce saltwater intrusion.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42441375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neo-deterministic seismic hazard maps of Kosovo","authors":"E. Brandmayr, V. Franco, Romanelli Fabio, V. Gordana, Panza Giuliano Francesco","doi":"10.15625/2615-9783/16328","DOIUrl":"https://doi.org/10.15625/2615-9783/16328","url":null,"abstract":"Kosovo is one of the most seismically active regions in Europe, lying within the Alpine-Mediterranean tectonic belt. Historical records for the region show several catastrophic earthquakes with epicentral intensity IX (MCS). However, due to Kosovo’s high population density, high prevalence of traditional construction, and insufficient enforcement of building codes, Kosovo is vulnerable to earthquake damage. In this study, we present earthquake hazard maps for bedrock conditions in Kosovo based on the well-known Neo-deterministic Seismic Hazard Assessment (NDSHA) method. NDSHA relies upon the fundamental physics of wave generation and propagation in complex geologic structures to generate realistic time series, used as input for the computation of several ground motion parameters, integrating the available knowledge of seismic history, seismogenic zones and morphostructural nodes. In accordance with continuum mechanics, the tensor nature of earthquake ground motion is preserved, producing realistic signals using structural models obtained by tomographic inversion and earthquake source information readily available in literature. Our maps are generally consistent with the observed intensity IX (MCS) and suggest that, in some instances, intensity X could be reached.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49240420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monitoring spatial-temporal dynamics of small lakes based on SAR Sentinel-1 observations: a case study over Nui Coc Lake (Vietnam)","authors":"Binh Pham Duc, Son Tong Si","doi":"10.15625/2615-9783/16315","DOIUrl":"https://doi.org/10.15625/2615-9783/16315","url":null,"abstract":"For the first time, this study estimates the variation of surface water extent of Nui Coc Lake located in Thai Nguyen province in North Vietnam at high spatial (20 m) and temporal resolution (bi-weekly). The classification methodology was developed based on the use of the Otsu threshold algorithm on the histogram of the backscatter coefficient of the SAR Sentinel-1 signal. Totally, more than 150 SAR Sentinel-1 images have been processed for the 2016-2020 period. Except for extreme drought and flood conditions, the average minimum and maximum of the lake’s surface water extent are 17 km2 (in May) and 24 km2 (in September/October), respectively, and Nui Coc Lake’s surface water was stable during the last five years. Classification results are in good agreement with the corresponding surface water extent maps derived from free-cloud Sentinel-2 images, with the occurrence map derived from the Landsat-derived Global Surface Water (GSW) product, and with in situ precipitation data. Compared to Sentinel-2, the lake’s surface water extent detected from Sentinel-1 is 4-4.5% less. The water occurrence is similar between our results and that derived from the GSW product, but Sentinel-1 data provide more details as its spatial resolution is higher than Landsat. This study clearly shows the great potential of SAR Sentinel-1 data for monitoring small lake’s water surface at low costs, especially over tropical regions.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49272286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direction of urban expansion in the Bangkok Metropolitan Area, Thailand under the impacts of a national strategy","authors":"Can Trong Nguyen, Diep Nguyen Thi Hong, Iabchoon Sanwit","doi":"10.15625/2615-9783/16313","DOIUrl":"https://doi.org/10.15625/2615-9783/16313","url":null,"abstract":"The Eastern Economic Corridor project (EEC), which spans over three coastal provinces east of the Bangkok Metropolitan Area (BMA), aims to transform Thailand into a developed country progressively. The EEC project promises to influence its territory and surrounding areas. We aimed to monitor the urbanized directions at the BMA during 2015-2017 and explore whether the BMA’s urban expansion trend is related to the EEC. The results revealed that the built-up areas increased by 24,033 hectares (22.8%). The urban districts with high urban density slowly developed, while the rural districts tended to urbanize with a high urbanization rate, approximately 6.8% per year. The BMA urban areas mainly expanded to the east (14.9% per year) and southeast (21.6% per year) under partial impacts from the EEC infrastructure projects. The research findings represent a concept for assessing urban expansion and pointing to the regions of concern, which will be meaningful for urban planning and policymaking.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45667706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Holocene sedimentation offshore Southeast Vietnam based on geophysical interpretation and sediment composition analysis","authors":"L. H. Van, T. N. Tien, Tuan Vu Tat, T. Thanh, Anh Nguyen Lam, Din Dao Bui, D. L. Van, Dien Tran Ngoc, Hiep Nguyen Huu","doi":"10.15625/2615-9783/16268","DOIUrl":"https://doi.org/10.15625/2615-9783/16268","url":null,"abstract":"Offshore Southeast (SE) Vietnam is considered a transition zone, with the sedimentary evolution of this area controlled by land-sea interactions, especially by the Holocene sea-level rise. This study presents some new findings regarding Holocene sedimentation and its linkage to the heavy mineral placers within the study area based on high-resolution seismic interpretation and sediment analysis. Our obtained results show that the Holocene sediments directly overlie the Late Pleistocene sedimentary formation, from which they are separated by an erosional/unconformity surface (R­1­ seismic reflector). Sediments deposited in the Early (~11.7-8.2kyr BP), Middle-Late (8.2kyr BP-present-day) Holocene sub-epochs correspond to the Transgressive and Highstand System tracts, which were closely controlled by the three stages of Holocene sea-level rise. The recent sediments distributed on the seafloor are dominated by sand and gravelly sand, demonstrating high-energy conditions, while the heavy minerals are rich in ilmenite and zircon. Most of these are concentrated along the present shoreline zones, but we do not exclude their accumulation in the paleo-shoreline and incised channels. Two ilmenite dispersion halos (1st and 2nd order) and one zircon dispersion halo (1st order) suggest that ilmenite and zircon are the most dominant heavy minerals while gold is only observed locally. The minerals were potentially derived from the weathering products of the Triassic-Cretaceous ilmenite-, zircon-, and gold-bearing granite and granitoid in central Vietnam.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43709599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Use fly ash for the production of lightweight building materials","authors":"Lan Tran Thi, Duong Nguyen Anh, Anh Phan Luu, Man Tran Thi","doi":"10.15625/2615-9783/16204","DOIUrl":"https://doi.org/10.15625/2615-9783/16204","url":null,"abstract":"Fly ash is a waste byproduct of thermal power plants or steel plants with a low density. Study on using fly ash to produce lightweight construction materials will is a new application of this material resource. Pha Lai fly ash is a byproduct from Pha Lai Thermal Power Joint Stock Company, in which the main mineral component was mullite (15-20%), quartz (14-16%), carbon (5-7%). The content of the amorphous component was about 67-73%. The chemical composition of Pha Lai mainly was SiO2 (51.73%), Al2O3 (23.22%), Fe2O3 (4.23%). To fabricate the lightweight material from Pha Lai fly ash, the fly ash was mixed with additive materials to create binders following two ways: (1) lime + fly ash and (2) geopolymer technology. For the way of lime + fly ash, with the optimal mixture ratio was fly ash:lime: water = 10:2:1, the lightweight material samples had the bulk density of 1.32g/cm3, the compressive strength of 3.91 MPa, satisfied the Vietnamese standard TCVN 6477-2011 for concrete bricks. Applying the geopolymer technology, with the optimal mixture ratio was fly ash: NaOH/Na2SiO3: Al powder = 100:45:0.15, NaOH/Na2SiO3 ratio = 1:2, the lightweight materials obtained the bulk density of 0,62g/cm3, the compressive strength of 1,54 MPa, satisfied the Vietnamese standard TCVN:9029-2017 for Lightweight concrete - Foam concrete and non-autoclaved concrete products-specification.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47241945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Methane flux and gas hydrate accumulations in the Sea of Okhotsk and their ecological aspects","authors":"N. Sokolova, Yu. A. Telegin, A. Obzhirov","doi":"10.15625/2615-9783/16193","DOIUrl":"https://doi.org/10.15625/2615-9783/16193","url":null,"abstract":"Methane is one of the important representatives of the organic substances in the atmosphere (for example, an increase of methane content in the atmosphere can affect enhancing the greenhouse effect). Gas hydrates are an essential part of links in the methane cycle and the accompanying fluxes of other gases. The research object in this paper is the Sea of Okhotsk, where gas hydrate fields and active submarine gas discharge areas were found. The study of methane fluxes is relevant both for the Sea of Okhotsk and the World Ocean. From 1984 to 2015, the background and anomalous methane fields were explored in the Sea of Okhotsk as a result of gas geochemical research carried out by scientists of the Gasgeochemistry Laboratory (POI FEB RAS). The flux of natural gas became stronger from the sources to the seafloor, from the seafloor to the water, and, finally, to the atmosphere due to renew of fault zones. Moreover, the amount of methane vents on the Sakhalin slope has increased from 2-3 vents to more than 400. The most representative hydroacoustic anomalies “flares” mapped direct methods study methane hydrates. The received outcomes indicate the urgency of the study of methane fluxes and the formation-dissociation mechanism of gas hydrates, and the influence of natural gas from hydrocarbon sources on the environment.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46284141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late pleistocene movement of Nam O - Nam Dong fault: evidence from electron spin resonance dating of fault gouge in the Western Da Nang city","authors":"Hung Nguyen Quoc, Hai Tran Thanh, Dao Vu Anh, T. Xuan","doi":"10.15625/2615-9783/16198","DOIUrl":"https://doi.org/10.15625/2615-9783/16198","url":null,"abstract":"The Nam O - Nam Dong fault is rated as one of the most seismic source zones in Central Vietnam. Field investigation in the mountainous areas in the Cam Le and Hoa Vang districts (Da Nang city), which is a part of the Nam O - Nam Dong fault zone, the authors have discovered fault gouge zone of 5-40 cm width within the Dai Loc granitic rock. Two fault gouge samples were collected for Electron spin resonance (ESR) dating. The results from the ESR dating on the quartz grains from the fault gouge samples showed the youngest age from the smallest fraction, probably indicating that ESR signals in the fractions were completely zeroed at the time of faulting due to frictional heat. The preliminary results from the ESR dating on the quartz grains from the fault gouge indicate that the last major faulting in this site was later the ages of 15.05±3.55 ka to 18.21±4.06 ka ago. Multiple actives during the late Pleistocene - Holocene of this fault had uplifted the fault gouge from a depth-seated to the present-day locality. These data suggest that this fault zone can be classified as a potentially active fault zone and presents some seismic hazards.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47345980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}