scholarly journals Long-Term Geomorphological Evolution of the Mouth Bar in the Modaomen Estuary of the Pearl River over the Last 55 Years (1964–2019)

Water ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 90
Author(s):  
Zhiyuan Han ◽  
Huaiyuan Li ◽  
Hualiang Xie ◽  
Bing Yan ◽  
Mingxiao Xie

Based on mass bathymetric data and remote sensing data in the Modaomen Estuary, this study explored the long-term evolutionary characteristics of the mouth bar in the Modaomen Estuary of the Pearl River from 1964 to 2019. In the past 55 years, due to the impact of human activities, such as shoal reclamation and estuarine regulation in the Modaomen Estuary, the river mouth moved out of the shallow sea covered by several islands and faced the South China Sea directly. Therefore, the mouth bay became a siltation center in the estuarine region and expanded outwards, gradually evolving a geomorphic pattern with three shallow shoals and two distributary branches; a west branch as the main branch accompanied by a small east branch. Over the past decade, high-intensity sand dredging activities in the mouth bar have led to a considerable deepening of the water depth and a significant refinement of bed sediments, forming a discharge pattern of a wide and shallow channel flowing into the sea. Therefore, the evolutionary characteristics of the mouth bar have become abnormal in recent years, so additional field bathymetric data and hydrological data are required for further research regarding the subsequent evolution of the mouth bar, against the background of a significant reduction of sediment discharge and high-intensity human activities.

2021 ◽  
Vol 9 (12) ◽  
pp. 1327
Author(s):  
Changjie Liu ◽  
Ziyue Zhong ◽  
Yiqing Xiao ◽  
Xiaoqi Chen ◽  
Minghui Yu

Over the past few decades, the topography and river-tide-salt dynamic characteristics of the Pearl River Delta (PRD) have undergone a myriad of changes due to the unnatural evolution process induced by diverse human activities, such as dam construction, land reclamation, sand excavation, and dredging for navigation. To investigate the impact of human activities on hydrodynamic structures in the PRD of the Modaomen Estuary (ME) during the dry season, a three-dimensional river-tide-salt dynamic model was used to simulate the hydrodynamic characteristics of the ME for different historical periods. The model results indicate that large-scale land reclamation weakened the tidal dynamics and mixing effects in the ME, promoting gravity circulation with opposite velocity directions at the surface and bottom within 15 km downstream of the estuary. Additionally, riverbed downcutting enhanced the tidal dynamics, which intensified saltwater intrusion, leading to the spatial scale-of-gravity circulation expanding 1–2 times. The enhancement of riverbed downcutting on the tidal dynamics in the ME was significantly greater than the weakening effect of land reclamation. Hence, due to the comprehensive influence of human activities between the 1970s and 2010, the hydrodynamic structures in the ME changed from a state of atypical gravity circulation, with nonobvious stratification, to a state of highly stratified and large-scale gravity circulation. The pollutant diffusion in the ME under different scenarios is also discussed in this paper. The results show that reclamation results in weakening of tidal dynamics, which is not conducive to the mixing and diffusion of pollutants in the estuary. However, the narrowed estuary due to land reclamation is conducive to the rapid entry of pollutants into the open sea.


2021 ◽  
pp. 003329412110051
Author(s):  
Rashmi Gupta ◽  
Jemima Jacob ◽  
Gaurav Bansal

Psychosocial stressors and social disadvantages contribute to inequalities in opportunities and outcomes. In the current paper, we use an epidemiological perspective and highlight the role stress plays on individuals by reviewing the outcomes of major stressors such as poverty and unemployment. We further analyzed the psychological and physical cost of these stressors and their long-term impact. We examined the role of universal basic income and closely looked at income experiments that were implemented in the past, in terms of their effectiveness in enhancing the community as well as individual outcomes and propose the UBI as a tool for alleviating the impact of these stressors. At a time when a major pandemic (e.g., COVID-19) threatens economic stability and health globally, we believe the UBI is relevant now, more than ever.


2017 ◽  
Vol 46 (1) ◽  
pp. 3-25 ◽  
Author(s):  
Travis N. Ridout ◽  
Erika Franklin Fowler ◽  
Michael M. Franz ◽  
Kenneth Goldstein

Scholars agree that there has been an increase in polarization among political elites, though there continues to be debate on the extent to which polarization exists among the mass public. Still, there is general agreement that the American public has become more sorted over the past two decades, a time during which political ad volumes have increased and ads have become more negative. In this research, we explore whether there is a link between the two. We take advantage of variation in the volume and tone of political advertising across media markets to examine the link between advertising and three dependent variables: issue polarization, affective polarization, and sorting. We focus on the impact of both recent ad exposure and cumulative ad exposure across several election cycles. Ultimately, we find little impact of advertising on polarization or sorting, both overall and among subgroups of the population.


Author(s):  
N. Dolzhenko ◽  
E. Mailyanova ◽  
I. Assilbekova ◽  
Z. Konakbay

Cloudiness and range of visibility are the most significant flight conditions for aircraft. The impact of clouds and visibility on the safety of aircraft flights, especially small aircraft, cannot be overestimated. According to the Interstate Air Committee, Kazakhstan ranks second in the number of aviation disasters. The average age of a third of Kazakhstan's small aircraft is more than 30 years. Over the past few years, 14 air accidents have occurred in the Republic of Kazakhstan, 11 of them with small aircraft. In this work, we investigate long-term data on cloudiness and visibility at the most weather-favorable airfield in Balkhash, for the possibility of safe and economical flights of small aircraft and planning training flights.


2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Paul C Langley ◽  
Taeho Greg Rhee

Over the past 20 years a number of simulations or models have been developed as a basis for tracking and evaluating the impact of pharmacological and other interventions in type 1 and type 2 diabetes mellitus. These models have typically tracked the natural course of these diseases generating long-term composite claims for cost-effectiveness. These claims can extend over the lifetime of the modeled patient cohort. Set against the standards of normal science, however, these claims lack credibility. The claims presented are all too often either immune to failure or are presented in a form that is non-testable. As such they fail to meet the key experimental requirements of falsification and replication. Unfortunately, there is a continuing belief that long-term or lifetime models are essential to decision-making. This is misplaced. The purpose of this review is to argue that there is a pressing need to reconsider the needs of health system decision makers and focus on modeled or simulated claims that are meaningful, testable, reportable and replicable in evaluating interventions in diabetes mellitus.   Type: Commentary


2020 ◽  
Vol 245 ◽  
pp. 105125 ◽  
Author(s):  
Xuanxuan Wang ◽  
Yaning Chen ◽  
Zhi Li ◽  
Gonghuan Fang ◽  
Fei Wang ◽  
...  

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