Pub Date : 2021-12-08DOI: 10.25073/2588-1094/vnuees.4846
Nguyen Thi Ha Thanh, Nguyen Ngoc Diep, Nguyen Huu Duy, Dang Dinh Kha, P. Le Tuan, Bui Ngoc Tu
Flood is a frequent natural disaster which has a negative impact on the socio-economic activities of the community in the lower Gianh river area - one of the most vulnerability areas under the flood in the North Central Region, Vietnam. The aim of this paper is to assess the risk of flooding in the study area as well as point out the factors that increase the vulnerability of the local community. The study applies UNESCO-IHE vulnerability approach, combining the flood risk assessment method by MIKE FLOOD model and sociological investigation, with 90 household questionnaires (selected randomly and door-to-door interview). The main results include flood risk level maps (by analyzing inundation depth and flood flow velocities); data on community resilience to flood (resilience capacity and local people's perceptions on flood risks). These results are the basis for not only raising awareness about flood risks but also propose non-structural flood protection solutions for managers and local communities in the research areas.
{"title":"Research on the Vulnerability of the Community to Flood: A Case Study at the Downstream of Gianh River, Quang Binh Province","authors":"Nguyen Thi Ha Thanh, Nguyen Ngoc Diep, Nguyen Huu Duy, Dang Dinh Kha, P. Le Tuan, Bui Ngoc Tu","doi":"10.25073/2588-1094/vnuees.4846","DOIUrl":"https://doi.org/10.25073/2588-1094/vnuees.4846","url":null,"abstract":"Flood is a frequent natural disaster which has a negative impact on the socio-economic activities of the community in the lower Gianh river area - one of the most vulnerability areas under the flood in the North Central Region, Vietnam. The aim of this paper is to assess the risk of flooding in the study area as well as point out the factors that increase the vulnerability of the local community. The study applies UNESCO-IHE vulnerability approach, combining the flood risk assessment method by MIKE FLOOD model and sociological investigation, with 90 household questionnaires (selected randomly and door-to-door interview). The main results include flood risk level maps (by analyzing inundation depth and flood flow velocities); data on community resilience to flood (resilience capacity and local people's perceptions on flood risks). These results are the basis for not only raising awareness about flood risks but also propose non-structural flood protection solutions for managers and local communities in the research areas. \u0000 ","PeriodicalId":247618,"journal":{"name":"VNU Journal of Science: Earth and Environmental Sciences","volume":"30 7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133678954","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}
Pub Date : 2021-12-08DOI: 10.25073/2588-1094/vnuees.4691
Dang Dinh Duc, Nguyen Xuan Loc, Nguyen Kim Cuong, Tran Thi Ngoc Anh
This paper presents the development of hydrodynamic simulation models (waves, currents) for the Vietnam East Sea and nestingto coastal area (applied in the coastal area of Phu Yen province). The COAWST modeling system has been used. This is an open source system which supports optimal parallel calculation and allows solving large-scale simulation problems. The model has been calibrated and verified by deep water wave data at the stations of Bach Long Vi, Con Co, Phu Quy and Phu Quoc for good results. Along with that, with the goal of having high resolution for the central Vietnam water, the model has been set up with coastal wave data in Phu Yen for very good results, the correlation coefficient between calculation and measurement is up to 0.95. The results of the current field, surface temperature from the model of the ocean shows the similarity with the verification data, especially simulating the typical rising water phenomenon in Ninh Thuan - Binh Thuan area. However, some stages have complicated movements, the model has not been closely simulated, for example in the area of Phu Quy island.
{"title":"Preliminary Results of Modelling Simulation for High-resolution Hydrodynamic Fields for Central Vietnam's Water","authors":"Dang Dinh Duc, Nguyen Xuan Loc, Nguyen Kim Cuong, Tran Thi Ngoc Anh","doi":"10.25073/2588-1094/vnuees.4691","DOIUrl":"https://doi.org/10.25073/2588-1094/vnuees.4691","url":null,"abstract":"This paper presents the development of hydrodynamic simulation models (waves, currents) for the Vietnam East Sea and nestingto coastal area (applied in the coastal area of Phu Yen province). The COAWST modeling system has been used. This is an open source system which supports optimal parallel calculation and allows solving large-scale simulation problems. The model has been calibrated and verified by deep water wave data at the stations of Bach Long Vi, Con Co, Phu Quy and Phu Quoc for good results. Along with that, with the goal of having high resolution for the central Vietnam water, the model has been set up with coastal wave data in Phu Yen for very good results, the correlation coefficient between calculation and measurement is up to 0.95. The results of the current field, surface temperature from the model of the ocean shows the similarity with the verification data, especially simulating the typical rising water phenomenon in Ninh Thuan - Binh Thuan area. However, some stages have complicated movements, the model has not been closely simulated, for example in the area of Phu Quy island. \u0000 ","PeriodicalId":247618,"journal":{"name":"VNU Journal of Science: Earth and Environmental Sciences","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130910531","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}
This study attempts to develop the MIKE FLOOD model to simulate Ky Lo river flooding using two major floods in November 2009, November 2010 and survey results carried out in June and Octover 2019 by State Level Project ĐTĐL.CN.33/18 for calibration and validation. The results showed good agreements between simulated water level/discharge and observations. The model was then applied to simulate and assess floods in Ky Lo river basin under the impacts of climate change and sea-level rise until 2030 and 2070 using RCP 8.5 scenario issued by MONRE. The results showed that maximum flooding area downstream of Ky Lo river basin in 2030 was around 9.128 ha and in 2070 was 9.562 ha, corresponding to 100-year flood event, mostly concentrated in Chi Thanh, An Ninh Tay, An Cu, An Ninh Dong and An Chan communes of Tuy An district.
本研究试图利用2009年11月、2010年11月的两次大洪水和国家一级项目ĐTĐL.CN 2019年6月和10月的调查结果，开发MIKE FLOOD模型来模拟基洛河洪水。33/18用于校准和验证。结果表明，模拟水位/流量与观测值吻合较好。应用该模型对2030年和2070年气候变化和海平面上升影响下的基洛河流域洪水进行了模拟和评估。结果表明:2030年基洛河流域下游最大洪涝面积约为9.128 ha, 2070年最大洪涝面积为9.562 ha，对应百年一遇的洪涝事件，主要集中在图安区的池清、安宁泰、安固、安宁东和安禅公社。
{"title":"Simulation of Flooding in the Ky Lo River Basin, Phu Yen Province Under the Impacts of Climate Change and Sea Level Rise","authors":"Nguyen Bach Tung, Dang Dinh Duc, Tran Thi Ngoc Anh, Tran Thanh Tung","doi":"10.25073/2588-1094/vnuees.4695","DOIUrl":"https://doi.org/10.25073/2588-1094/vnuees.4695","url":null,"abstract":"This study attempts to develop the MIKE FLOOD model to simulate Ky Lo river flooding using two major floods in November 2009, November 2010 and survey results carried out in June and Octover 2019 by State Level Project ĐTĐL.CN.33/18 for calibration and validation. The results showed good agreements between simulated water level/discharge and observations. The model was then applied to simulate and assess floods in Ky Lo river basin under the impacts of climate change and sea-level rise until 2030 and 2070 using RCP 8.5 scenario issued by MONRE. The results showed that maximum flooding area downstream of Ky Lo river basin in 2030 was around 9.128 ha and in 2070 was 9.562 ha, corresponding to 100-year flood event, mostly concentrated in Chi Thanh, An Ninh Tay, An Cu, An Ninh Dong and An Chan communes of Tuy An district. \u0000 ","PeriodicalId":247618,"journal":{"name":"VNU Journal of Science: Earth and Environmental Sciences","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127619355","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}
Pub Date : 2021-12-04DOI: 10.25073/2588-1094/vnuees.4690
Pham Thi Huong, C. Nguyen, Dinh Van Uu
This paper presents the comprehensive dataset of satellite data, shoreline detection methodology, and shoreline changes in the coast of Haiphong province from 1987 to 2018. Landsat satellite images from 1987 to 2018 were gathered. With this dataset, based on the metadata of images, only the images with the similar water level (~1.8 m) and high quality were selected for detecting the shoreline using modification of normalized difference index (MNDWI). These generations of shoreline will be processed using GIS technique for retrieving the detail shoreline changes in the tidal dominated estuarine region as Haiphong coast. It should be noted that in the study area, the change of shoreline mostly comes from the human activities as reclaimation or aquaculture. However, the landward movement of Hoang Chau warp proved that the sea forcings are dominant compared to them from rivers in the Haiphong bay.
{"title":"Investigation of Shoreline Changes in the Coast of Haiphong Province from 1987 to 2018","authors":"Pham Thi Huong, C. Nguyen, Dinh Van Uu","doi":"10.25073/2588-1094/vnuees.4690","DOIUrl":"https://doi.org/10.25073/2588-1094/vnuees.4690","url":null,"abstract":"This paper presents the comprehensive dataset of satellite data, shoreline detection methodology, and shoreline changes in the coast of Haiphong province from 1987 to 2018. Landsat satellite images from 1987 to 2018 were gathered. With this dataset, based on the metadata of images, only the images with the similar water level (~1.8 m) and high quality were selected for detecting the shoreline using modification of normalized difference index (MNDWI). These generations of shoreline will be processed using GIS technique for retrieving the detail shoreline changes in the tidal dominated estuarine region as Haiphong coast. It should be noted that in the study area, the change of shoreline mostly comes from the human activities as reclaimation or aquaculture. However, the landward movement of Hoang Chau warp proved that the sea forcings are dominant compared to them from rivers in the Haiphong bay. \u0000 ","PeriodicalId":247618,"journal":{"name":"VNU Journal of Science: Earth and Environmental Sciences","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129487228","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}
Pub Date : 2021-12-04DOI: 10.25073/2588-1094/vnuees.4683
Nguyen Tri Quang Hung, Le Xuan Hien
Assess the trend of rainfall change in Phu Quoc island is an interesting topic which establishes a scientific basis for rainfall forecast trends as well as regional development planning. Rainfall measurement data from 1985 to 2018 was used to analyse with different methods included Sen’s slope, linear regression, Mann-Kendall (MK) test, CV coefficient (Coefficient of Variation), PCI (Precipitation Concentration Index); examine drought level over time by using SPI - standardized rainfall index. Results show that, according to the linear regression analysis, regional annual rainfall is not much fluctuated, the rainy season and annual rainfall tend to decrease, while rainfall in the dry season tends to increase. According to Sen’s slope chart, July rain gains highest increasement, while that of August tends to decrease most. In general, the precipitation concentration index revealed the presence of a high and very high concentration of rainfall.
{"title":"Trend Analysis of Rainfall in the Phu Quoc Island","authors":"Nguyen Tri Quang Hung, Le Xuan Hien","doi":"10.25073/2588-1094/vnuees.4683","DOIUrl":"https://doi.org/10.25073/2588-1094/vnuees.4683","url":null,"abstract":"Assess the trend of rainfall change in Phu Quoc island is an interesting topic which establishes a scientific basis for rainfall forecast trends as well as regional development planning. Rainfall measurement data from 1985 to 2018 was used to analyse with different methods included Sen’s slope, linear regression, Mann-Kendall (MK) test, CV coefficient (Coefficient of Variation), PCI (Precipitation Concentration Index); examine drought level over time by using SPI - standardized rainfall index. Results show that, according to the linear regression analysis, regional annual rainfall is not much fluctuated, the rainy season and annual rainfall tend to decrease, while rainfall in the dry season tends to increase. According to Sen’s slope chart, July rain gains highest increasement, while that of August tends to decrease most. In general, the precipitation concentration index revealed the presence of a high and very high concentration of rainfall. \u0000 ","PeriodicalId":247618,"journal":{"name":"VNU Journal of Science: Earth and Environmental Sciences","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130922601","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}
Pub Date : 2021-06-27DOI: 10.25073/2588-1094/vnuees.4639
Le Tien Dung, Dao Hong Quang
Face spall in moderate strength coal seam occurs less frequently but can be more severe and takes a longer time to remedy compared to face spall in the weak coal seam. This paper presents a field investigation of face spall in moderate strength coal seam at Face I-8-1, Vang Danh coal mine, Quang Ninh coal field, Vietnam. The leg pressure of shield support and face condition were monitored within two months, and on-site remedial measures to the spall were discussed. The monitoring results confirmed that the front and rear leg pressure profiles are consistent with world-wide observations. The coal face condition in actual operation was found to be more stable than that in project design. The face spall occurred along face dip direction, but mostly in small extent of less than 0.5 m deep and during transitional time between working shifts. Proper ground control near gate ends by using higher capacity shield supports and supplemental hydraulic props was identified to improve face stability in the area. On-site remedial measures proved their efficiency in small to moderate face spall extent. For main roof rupture-associated face spall, technical measures have been applied but they need further investigation to clarify their effectiveness. The paper’s results can be consulted to improve longwall face stability control in similar coal seam conditions.
{"title":"Field Investigation of Face Spall in Moderate Strength Coal Seam at Vang Danh Coal Mine, Vietnam","authors":"Le Tien Dung, Dao Hong Quang","doi":"10.25073/2588-1094/vnuees.4639","DOIUrl":"https://doi.org/10.25073/2588-1094/vnuees.4639","url":null,"abstract":"Face spall in moderate strength coal seam occurs less frequently but can be more severe and takes a longer time to remedy compared to face spall in the weak coal seam. This paper presents a field investigation of face spall in moderate strength coal seam at Face I-8-1, Vang Danh coal mine, Quang Ninh coal field, Vietnam. The leg pressure of shield support and face condition were monitored within two months, and on-site remedial measures to the spall were discussed. The monitoring results confirmed that the front and rear leg pressure profiles are consistent with world-wide observations. The coal face condition in actual operation was found to be more stable than that in project design. The face spall occurred along face dip direction, but mostly in small extent of less than 0.5 m deep and during transitional time between working shifts. Proper ground control near gate ends by using higher capacity shield supports and supplemental hydraulic props was identified to improve face stability in the area. On-site remedial measures proved their efficiency in small to moderate face spall extent. For main roof rupture-associated face spall, technical measures have been applied but they need further investigation to clarify their effectiveness. The paper’s results can be consulted to improve longwall face stability control in similar coal seam conditions. \u0000 ","PeriodicalId":247618,"journal":{"name":"VNU Journal of Science: Earth and Environmental Sciences","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116221777","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}
Pub Date : 2021-06-27DOI: 10.25073/2588-1094/vnuees.4620
B. Thom, T. Cuong, L. H. Phong, T. Hieu, N. Anh
By integration of remote sensing images analysis, geology, geomorphology, hydrogeology, geophysical method, and drilling data, the paper illustrates the structure tectonics, causes, and initial mechanism of a sinkhole forming in Bang Lung, Cho Don, Bac Kan province. The NE-SW normal slip faults are an essential fault system in the area, which created Bang Lung graben valley. This fault system also forms large fracture zones, creating advantage conditions for the groundwater runoff both vertically and horizontally to eroded and dissolved carbonate rock-forming underground karst caves. These are favorable natural conditions for forming a sinkhole. The sinkhole hazard in the Bang Lung area is initiated by some main factors such as tectonic activity, thickness, and characteristics of unconsolidated sediment layers, groundwater fluctuation, karst caves, and human activities. The most human impacts are mining exploitation and agricultural cultivation that promote sinkholes occurring faster and earlier. The horizontal and vertical movement of groundwater dragged the material on the ceiling karst caves into ground spaces. Thereby, weakening the cohesion of the unconsolidated sediment above caves leads to gravitational unbalance and creates a sinkhole. This study has also shown potential sinkhole areas in Bang Lung, which helps the authorities and local people in sinkhole prevention and mitigation mission.
{"title":"Tectonic Structure and Relationship with Sinkhole Harzard in Bang Lung Area, Cho Don District, Bac Kan Province","authors":"B. Thom, T. Cuong, L. H. Phong, T. Hieu, N. Anh","doi":"10.25073/2588-1094/vnuees.4620","DOIUrl":"https://doi.org/10.25073/2588-1094/vnuees.4620","url":null,"abstract":"By integration of remote sensing images analysis, geology, geomorphology, hydrogeology, geophysical method, and drilling data, the paper illustrates the structure tectonics, causes, and initial mechanism of a sinkhole forming in Bang Lung, Cho Don, Bac Kan province. The NE-SW normal slip faults are an essential fault system in the area, which created Bang Lung graben valley. This fault system also forms large fracture zones, creating advantage conditions for the groundwater runoff both vertically and horizontally to eroded and dissolved carbonate rock-forming underground karst caves. These are favorable natural conditions for forming a sinkhole. The sinkhole hazard in the Bang Lung area is initiated by some main factors such as tectonic activity, thickness, and characteristics of unconsolidated sediment layers, groundwater fluctuation, karst caves, and human activities. The most human impacts are mining exploitation and agricultural cultivation that promote sinkholes occurring faster and earlier. The horizontal and vertical movement of groundwater dragged the material on the ceiling karst caves into ground spaces. Thereby, weakening the cohesion of the unconsolidated sediment above caves leads to gravitational unbalance and creates a sinkhole. This study has also shown potential sinkhole areas in Bang Lung, which helps the authorities and local people in sinkhole prevention and mitigation mission. \u0000 ","PeriodicalId":247618,"journal":{"name":"VNU Journal of Science: Earth and Environmental Sciences","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130985538","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}
Pub Date : 2021-06-27DOI: 10.25073/2588-1094/vnuees.4605
N. Long, T. V. Anh, Bui Khac Luyen
Mining-induced subsidence is often determined by field survey methods, e.g., using total station or global navigation satellite system (GNSS) technology. The advantage of these methods is high accuracy, but they are usually employed in a small-scale areas. Radar technology has been developed and applied to determine surface subsidence over a large area at a few millimeters accuracy. In this paper, 24 Sentinel-1B SAR images are used with the Permanent Scatter Interferometry (PSInSAR) method to determine the land subsidence of the Tan My-Thuong Tan quarries and surrounding areas in Binh Duong province, Vietnam. The results are compared with the average annual subsidence of 20 GNSS surveying points from January 2018 to March 2020. The correlation coefficient of annual average land subsidence of the two methods is bigger than 0.8, indicating the feasibility of applying the InSAR Sentinel-1 data processed by the PSInSAR method to determine the mining-induced subsidence of ground surfaces over quarries and surrounding areas.
{"title":"Determination of Ground Subsidence by Sentinel-1 SAR Data (2018-2020) over Binh Duong Quarries, Vietnam","authors":"N. Long, T. V. Anh, Bui Khac Luyen","doi":"10.25073/2588-1094/vnuees.4605","DOIUrl":"https://doi.org/10.25073/2588-1094/vnuees.4605","url":null,"abstract":"Mining-induced subsidence is often determined by field survey methods, e.g., using total station or global navigation satellite system (GNSS) technology. The advantage of these methods is high accuracy, but they are usually employed in a small-scale areas. Radar technology has been developed and applied to determine surface subsidence over a large area at a few millimeters accuracy. In this paper, 24 Sentinel-1B SAR images are used with the Permanent Scatter Interferometry (PSInSAR) method to determine the land subsidence of the Tan My-Thuong Tan quarries and surrounding areas in Binh Duong province, Vietnam. The results are compared with the average annual subsidence of 20 GNSS surveying points from January 2018 to March 2020. The correlation coefficient of annual average land subsidence of the two methods is bigger than 0.8, indicating the feasibility of applying the InSAR Sentinel-1 data processed by the PSInSAR method to determine the mining-induced subsidence of ground surfaces over quarries and surrounding areas. \u0000 ","PeriodicalId":247618,"journal":{"name":"VNU Journal of Science: Earth and Environmental Sciences","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122957200","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}
Pub Date : 2021-06-26DOI: 10.25073/2588-1094/vnuees.4535
Tran Thi Hoang Yen, Tran Thanh Thai, N. V. Tu, N. X. Quang, P. Lưu
Chlorophyll-a (Chl-a) has been used extensively as an essential indicator of trophic state in the assessment and monitoring of surface water quality environments. The environmental factors can influence Chl-a concentrations; thus, to determine the relationship between Chl-a concentration and factors. The research was carried out in dry season (March 2016) and wet season (September 2016) in Tri An reservoir, Dong Nai Province, Vietnam and performed by Spearman's correlation analysis and Linear regression analysis. The result showed that Chl-a varied between 12.84 and 783.51 µg/L and was quite different a cross stations in two surveys. Factor analysis and the best models revealed the association of strong physico-chemical with Chl-a concentration. The Chl-a was significantly positively correlated with Total Suspended Solids (TSS) and negative with Nitrate (NO3-) in the dry season, while in the wet season the positive relationships between Chl-a concentration and Dissolved Oxygen (DO), Temperature and a strong negatively correlated with Phosphate (PO43-) correlation were found. This relationships inferred that the nutrients brought by the influx of reservoir into the study area have contributed to control the growth and abundance of phytoplankton. Thus, the importance of environmental factors in structuring Chl-a concentration may be used to guide the conservation of the aquatic ecosystems in the reservoir.
{"title":"Environmental Factors Influencing Chlorophyll-a Concentration in Tri An Reservoir, Vietnam","authors":"Tran Thi Hoang Yen, Tran Thanh Thai, N. V. Tu, N. X. Quang, P. Lưu","doi":"10.25073/2588-1094/vnuees.4535","DOIUrl":"https://doi.org/10.25073/2588-1094/vnuees.4535","url":null,"abstract":"Chlorophyll-a (Chl-a) has been used extensively as an essential indicator of trophic state in the assessment and monitoring of surface water quality environments. The environmental factors can influence Chl-a concentrations; thus, to determine the relationship between Chl-a concentration and factors. The research was carried out in dry season (March 2016) and wet season (September 2016) in Tri An reservoir, Dong Nai Province, Vietnam and performed by Spearman's correlation analysis and Linear regression analysis. The result showed that Chl-a varied between 12.84 and 783.51 µg/L and was quite different a cross stations in two surveys. Factor analysis and the best models revealed the association of strong physico-chemical with Chl-a concentration. The Chl-a was significantly positively correlated with Total Suspended Solids (TSS) and negative with Nitrate (NO3-) in the dry season, while in the wet season the positive relationships between Chl-a concentration and Dissolved Oxygen (DO), Temperature and a strong negatively correlated with Phosphate (PO43-) correlation were found. This relationships inferred that the nutrients brought by the influx of reservoir into the study area have contributed to control the growth and abundance of phytoplankton. Thus, the importance of environmental factors in structuring Chl-a concentration may be used to guide the conservation of the aquatic ecosystems in the reservoir.","PeriodicalId":247618,"journal":{"name":"VNU Journal of Science: Earth and Environmental Sciences","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121647659","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}
Pub Date : 2021-06-26DOI: 10.25073/2588-1094/vnuees.4558
L. T. Hoài, Pham Nguyen Ha Vu, N. D. Nguyen, Hoàng Thị Thu Thảo, N. Vuong
The Song Tranh 2 hydropower reservoir was built in Tra My area, Quang Nam province, composing magmatic and high-grade metamorphic rocks of the northern part of the Kon Tum massif. Since the reservoir was put into operation, induced earthquakes have occurred in the Song Tranh 2 hydropower reservoir and its vicinity. Tectonically, the northwest-southeast to east-west striking faults developed strongly. Detailed analysis of slickensides and attitude of faults occurring in the studied area have shown that the northwest-southeast striking faults are reactivated as dextral ones during the Pliocene-Quaternary up to the present day. Based on the geometric distribution of the fault network, kinematic characteristics, and the youngest tectonic stress regime, we computed the distribution of tectonic stress in the studied area. Computation results show two positive anomalies of stress directly related to the northwest-southeast faults numbered 2, 10, 11a, 11b and sub-latitude striking fault numbered 1. These faults run in line with the local river channels and are likely to reactivate and generate induced earthquakes.
{"title":"Tectonic Stress Distribution in the Song Tranh 2 Hydropower Reservoir: Implication for Induced Earthquake","authors":"L. T. Hoài, Pham Nguyen Ha Vu, N. D. Nguyen, Hoàng Thị Thu Thảo, N. Vuong","doi":"10.25073/2588-1094/vnuees.4558","DOIUrl":"https://doi.org/10.25073/2588-1094/vnuees.4558","url":null,"abstract":"The Song Tranh 2 hydropower reservoir was built in Tra My area, Quang Nam province, composing magmatic and high-grade metamorphic rocks of the northern part of the Kon Tum massif. Since the reservoir was put into operation, induced earthquakes have occurred in the Song Tranh 2 hydropower reservoir and its vicinity. Tectonically, the northwest-southeast to east-west striking faults developed strongly. Detailed analysis of slickensides and attitude of faults occurring in the studied area have shown that the northwest-southeast striking faults are reactivated as dextral ones during the Pliocene-Quaternary up to the present day. Based on the geometric distribution of the fault network, kinematic characteristics, and the youngest tectonic stress regime, we computed the distribution of tectonic stress in the studied area. Computation results show two positive anomalies of stress directly related to the northwest-southeast faults numbered 2, 10, 11a, 11b and sub-latitude striking fault numbered 1. These faults run in line with the local river channels and are likely to reactivate and generate induced earthquakes. \u0000 ","PeriodicalId":247618,"journal":{"name":"VNU Journal of Science: Earth and Environmental Sciences","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128514436","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}
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