Artículos de revistas: "Estuary process"

1

van Buuren, A. y L. Gerrits. "Understanding and managing a complex estuary: the process towards more congruence between the physical system characteristics and the management system of the Westerschelde (Netherlands)". Hydrology and Earth System Sciences Discussions 5, n.º 3 (11 de junio de 2008): 1371–405. http://dx.doi.org/10.5194/hessd-5-1371-2008.

Texto completo

Resumen

Abstract. In this article, we expand on the relationship between the social processes of policymaking, management and research in the context of the Westerschelde estuary. This complex estuary system, located in Belgium and the Netherlands, has its own morphological and ecological characteristics and dynamics, and has three core functions: economically, it makes the port of Antwerp accessible; ecologically, it generates habitats for certain unique species; and in terms of safety, it prevents the hinterland from being flooded. We analyze how the social processes of policymaking, management and analysis have focused on these three aspects, and how they have affected the estuary. We proceed to develop a framework for evaluating the social system of policy-making, management and research. This framework focuses on the social system's adaptive capabilities (how it evolved in a non-linear fashion), integrative capacity (how the system's interconnectivity was taken into account), and participative competencies (how the different interests and insights regarding the estuary were absorbed). This framework was then applied to twenty years of policymaking about, management of, and research on the Westerschelde estuary. We conclude that, because of policy learning effects, policy/management and research take the estuary's self-organizing capacities into account much more than they did in the past. However, the self-referential behaviour of policymakers, managers and researchers makes it possible that an anthropocentric and technocratic approach towards managing the estuary, indicating a disconnection between the social and physical systems, could return.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Chu, Ao, Zhengbing Wang, Huib De Vriend y Marcel Stive. "A PROCESS-BASED APPROACH TO SEDIMENT TRANSPORT". Coastal Engineering Proceedings 1, n.º 32 (2 de febrero de 2011): 83. http://dx.doi.org/10.9753/icce.v32.sediment.83.

Texto completo

Resumen

A process-based model for the Yangtze Estuary is constructed to study the sediment transport in the estuary. The proposed model covers the entire tidal region of the estuary, the Hangzhou Bay and a large part of the adjacent sea. The dominant processes, fluvial and tidal, are included in the model. The calibration of the model against extensive flow, water level, salinity and suspended sediment data shows a good representation of observed phenomena. With the present calibrated and validated model, the residual flow field and the residual sediment transport field are obtained. The residual sediment transport pattern gives insight into the morphological behaviour of the mouth bars.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Ding, Yan, Keh-Chia Yeh y Shao-Tang Wei. "INTEGRATED COASTAL PROCESS MODELING AND IMPACT ASSESSMENT OF FLOATING AND SEDIMENTATION IN COASTS AND ESTUARIES". Coastal Engineering Proceedings, n.º 35 (23 de junio de 2017): 18. http://dx.doi.org/10.9753/icce.v35.management.18.

Texto completo

Resumen

In this study, an integrated coastal process model was applied to assess impact of coastal flooding and sedimentation in an estuary in Taiwan and to evaluate performance of proposed engineering plans for flood prevention and sedimentation management. This in-situ validated model was used to simulate and predict hydrodynamic processes and morphological changes induced by multiple hydrological forcing such as river flood flows, waves, tides, and storms surges from rivers to the estuary and its adjacent coasts. Simulation results quantified coastal flooding risks, erosions, sedimentation, and channel refilling. Predicted dynamic responses to typhoons and monsoons were utilized for identifying the most effective engineering plan to reshape the geometry of the estuary. After the selected engineering plan was accomplished, this model was applied again to further predict morphological changes in the newly-developed estuary. This paper demonstrates effectiveness of a simulation-based coastal and estuary planning approach to manage flood and sedimentation driven by complex physical processes from river flows, waves, tides, and sediment transport.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Chen, Ruirui, Xuezhong Jiang y Jing Chen. "Satellite Imagery Recording the Process and Pattern of Winter Temperature Field in Yangtze Estuary Interrupted by a Cold Wave". Atmosphere 14, n.º 3 (28 de febrero de 2023): 479. http://dx.doi.org/10.3390/atmos14030479.

Texto completo

Resumen

Sea surface temperature (SST) is a key marine ecological metric. An optimized split-window algorithm was used to invert the Yangtze Estuary’s temperature field during a cold wave process. Additionally, MODIS SST inversion results were used to explore the effects of typical cold waves on the Yangtze Estuary’s temperature field through the application of a temperature profile analysis method and a multiscale, multidirectional edge detection algorithm. According to the findings, (1) the cold wave altered the temperature field characteristics and the temperature front intensity, morphology, and spatial distribution pattern within the Yangtze Estuary for a short period. The strong temperature front displayed irregular edges and scattered patterns due to the combined effects of cold water masses produced by the cold wave and the tides and the warm water currents outside the mouth. (2) The cold wave caused significant short-term deviations in the Yangtze Estuary’s SST. The cold water tongue stretched across the entire Yangtze Estuary, where the temperature dropped sharply with time, with the maximum cooling occurring outside the mouth, at 12.2 °C, and the minimum cooling occurring inside the mouth, at only 5.5 °C. (3) The spatially gradual warming of the Yangtze Estuary’s SST from inside to outside the mouth became a low–lower–high pattern during cold waves. (4) The cold wave exhibited a greater influence on the strength, form, and distribution of the temperature front. Studying the effects of cold waves on the Yangtze Estuary’s temperature field has significant theoretical and practical implications for understanding the changes in the winter temperature field, environmental protection, disaster mitigation, and prevention.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Yin, Yunzhu, Harshinie Karunarathna y Dominic E. Reeve. "A Computational Investigation of Storm Impacts on Estuary Morphodynamics". Journal of Marine Science and Engineering 7, n.º 12 (20 de noviembre de 2019): 421. http://dx.doi.org/10.3390/jmse7120421.

Texto completo

Resumen

Global climate change drives sea level rise and changes to extreme weather events, which can affect morphodynamics of coastal and estuary systems around the world. In this paper, a 2D process-based numerical model is used to investigate the combined effects of future mean sea level and storm climate variabilities on morphological change of an estuary. Morphodynamically complex, meso-tidal Deben Estuary, located in the Suffolk at the east coast of the UK is selected as our case study site. This estuary has experienced very dynamic behaviors in history thus it might be sensitive to the future climate change. A statistical analysis of future storms around this area, derived from a global wave model, has shown a slight increase of storm wave heights and storm occurrences around the estuary in future as a result of global climate variations under medium emission scenario. By using a process-based model and by combining the forecast ‘end-of-century’ mean sea level with statistically derived storm conditions using projected storms over a time slice between 2075–2099, we determined hydrodynamic forcing for future morphodynamic modelling scenarios. It is found that the effect of increased sea level combined with future storms can significantly alter the current prevailing morphodynamic regime of the Deben Estuary thus driving it into a less stable system. It is also found that storm waves can be very significant to morphodynamic evolution of this tide-dominated estuary.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Dinh, Cham Dao. "Effects of hydrodynamical regime on morphological evolution at Cua Dai estuary and coastlines of Quang Nam province". VIETNAM JOURNAL OF EARTH SCIENCES 42, n.º 2 (9 de mayo de 2020): 176–86. http://dx.doi.org/10.15625/0866-7187/0/0/15005.

Texto completo

Resumen

In recent years, accretion-erosion processes are frequently recorded in the estuary of Cua Dai, Quang Nam province. Most recently, however, sand bars are formed in the estuary not far from the place where the Inland Waterways Authority of Vietnam had previously dredged. The estuary continues to be accreted by sand. These have been drawing special attention of national and international scientists. While there is accretion at the estuary, eroded processes are strongly recorded along the coastlines of Quang Nam province. Therefore, it is necessary to carry out a study in the effects of the hydrodynamic regime on morphological changes in the Cua Dai estuary and coastlines of Quang Nam province. The goal of this paper is to fully interpret the causes, regimes of accretion and erosion processes over the study area. In this study, satellite images and hydrodynamic models of Delft3D and MIKE 11 are applied. The results show a strong accretion process in the estuary of Cua Dai. Sandbar formation across the Cua Dai estuary comes from the interaction of flood, wave, and current conditions during the northeast monsoon. This mainly affects the changes in morphology in the estuary of Cua Dai, Quang Nam.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Dinh, Cham Dao. "Effects of hydrodynamical regime on morphological evolution at Cua Dai estuary and coastlines of Quang Nam province". VIETNAM JOURNAL OF EARTH SCIENCES 42, n.º 2 (9 de mayo de 2020): 176–86. http://dx.doi.org/10.15625/0866-7187/42/2/15005.

Texto completo

Resumen

In recent years, accretion-erosion processes are frequently recorded in the estuary of Cua Dai, Quang Nam province. Most recently, however, sand bars are formed in the estuary not far from the place where the Inland Waterways Authority of Vietnam had previously dredged. The estuary continues to be accreted by sand. These have been drawing special attention of national and international scientists. While there is accretion at the estuary, eroded processes are strongly recorded along the coastlines of Quang Nam province. Therefore, it is necessary to carry out a study in the effects of the hydrodynamic regime on morphological changes in the Cua Dai estuary and coastlines of Quang Nam province. The goal of this paper is to fully interpret the causes, regimes of accretion and erosion processes over the study area. In this study, satellite images and hydrodynamic models of Delft3D and MIKE 11 are applied. The results show a strong accretion process in the estuary of Cua Dai. Sandbar formation across the Cua Dai estuary comes from the interaction of flood, wave, and current conditions during the northeast monsoon. This mainly affects the changes in morphology in the estuary of Cua Dai, Quang Nam.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Shi, Honghua, Deliang Yu, Liting Yin, Yadong Sui, Yongzhi Liu, Shuqing Qiao, Weimin Wang, Wei Zheng y Dewen Ding. "Source-sink process of microplastics in watershed-estuary-offshore system". Journal of Cleaner Production 338 (marzo de 2022): 130612. http://dx.doi.org/10.1016/j.jclepro.2022.130612.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Hong, Bo, Wenping Gong, Shiqiu Peng, Qiang Xie, Dongxiao Wang, Haobo Li y Hongzhou Xu. "Characteristics of vertical exchange process in the Pearl River estuary". Aquatic Ecosystem Health & Management 19, n.º 3 (24 de junio de 2016): 286–95. http://dx.doi.org/10.1080/14634988.2016.1205438.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Wu, Dean, Yigang Wang, Yuchen Shao y Guodong Hu. "Simulation and Statistical Analysis on the Transport Process of Salt Water Mass from the North Branch in the Yangtze River Estuary". Journal of Physics: Conference Series 2224, n.º 1 (1 de abril de 2022): 012065. http://dx.doi.org/10.1088/1742-6596/2224/1/012065.

Texto completo

Resumen

Abstract Based on the analysis of measured data, a two-dimensional hydrodynamic Salinity Transport Model in the Yangtze River estuary is established by using Mike21 model. This model is used to study the average daily distribution and changing patterns of the saline water mass in the South Branch that are from the North Branch while only the saltwater intrusion from the North Branch is considered. It determines the intrusion process of saline water mass from the North Branch and the area that are affected by saline water intrusion. In addition, through the research of salt water mass core moving down and salinity variation in the south branch channel, the flow pattern and mechanism of salt water mass in the south branch channel are revealed. The saltwater intrusion from the North Branch has a great impact on the vertical, horizontal and vertical salinity fields of the Yangtze River estuary. The variation trend of statistical variance, deviation and standard deviation of the half month time series of salinity at each point along the route is basically the same, showing a gradual decreasing trend towards the downstream. Those show that the salinity dispersion is larger in the upstream estuary and lower outside the estuary. Combined with the salinity kurtosis and skewness, the deviation degree and direction of the salinity distribution at each point along the route can be judged, which can reflect the comprehensive process of runoff, tidal current and topography. Therefore, the kurtosis and skewness statistics can effectively describe the law of transport and dynamic characteristics of intrusion saline water masses in the Yangtze River Estuary.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Ariza-Colpas, Paola Patricia, Cristian Eduardo Ayala-Mantilla, Qaisar Shaheen, Marlon Alberto Piñeres-Melo, Diego Andrés Villate-Daza, Roberto Cesar Morales-Ortega, Emiro De-la-Hoz-Franco, Hernando Sanchez-Moreno, Butt Shariq Aziz y Mehtab Afzal. "SISME, Estuarine Monitoring System Based on IOT and Machine Learning for the Detection of Salt Wedge in Aquifers: Case Study of the Magdalena River Estuary". Sensors 21, n.º 7 (29 de marzo de 2021): 2374. http://dx.doi.org/10.3390/s21072374.

Texto completo

Resumen

This article contains methods, results, and analysis agreed for the development of an application based on the internet of things and making use of machine learning techniques that serves as a support for the identification of the saline wedge in the Magdalena River estuary, Colombia. As a result of this investigation, the process of identifying the most suitable telecommunications architecture to be installed in the estuary is shown, as well as the characteristics of the software developed called SISME (Estuary Monitoring System), and the results obtained after the implementation of prediction techniques based on time series. This implementation supports the maritime security of the port of Barranquilla since it can support decision-making related to the estuary. This research is the result of the project “Implementation of a Wireless System of Temperature, Conductivity and Pressure Sensors to support the identification of the saline wedge and its impact on the maritime safety of the Magdalena River estuary”.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Tivy, Joy. "The geography of the Estuary and Firth of Clyde". Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 90 (1986): 7–23. http://dx.doi.org/10.1017/s026972700000484x.

Texto completo

Resumen

SynopsisThe relative resource value and use of the Estuary and Firth of Clyde have varied through time. Until the eighteenth century the estuary was difficult to navigate. The firth, with its rich fishing grounds and sheltered harbours, was the focus of early settlement. However, increasing trade with the Americas, larger ships and growing competition between Glasgow and the more accessible ports of Greenock and Dumbarton stimulated plans to improve the navigability of the estuary. This was achieved by deepening and widening the main channel, a process which continued as the size of ships increased and more sophisticated techniques of river improvement developed. Within a century and a half the bed of the estuary was transformed from an obstacle to navigation into a major water-route, from which the largest passenger liners in the world were launched.Since the Second World War the relative resource values of the estuary and the firth have changed with the increase in air travel, the decline of ship building and heavy industry on the Clyde, and the increase in the size of cargo vessels. The economic focus shifted from the estuary to the natural, deepwater harbours of the firth.At present redevelopment of derelict docklands and industrial sites along the estuary is taking place, while the firth is suffering from the effects of economic recession. Planning is now being increasingly directed toward the development of the amenity, recreational and tourist potential of both the estuary and the firth.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Chen, Changsheng, Haosheng Huang, Huichan Lin, Jack Blanton, Chunyan Li y Francisco Andrade. "A Wet/Dry Point Treatment Method of FVCOM, Part II: Application to the Okatee/Colleton River in South Carolina". Journal of Marine Science and Engineering 10, n.º 7 (18 de julio de 2022): 982. http://dx.doi.org/10.3390/jmse10070982.

Texto completo

Resumen

The wet/dry point treatment method of FVCOM was applied to simulate the tide-induced flooding/drying process in the estuarine–tidal-creek–saltmarsh complex of the Okatee/Colleton River Estuary, South Carolina. The simulation results were compared with observed currents at three mooring sites and flooded areas observed from remote-sensing hypsometric measurements, demonstrating that FVCOM can robustly reproduce tidal and residual currents in the river and the flooding process onto the intertidal saltmarsh. The simulated flow field reveals that the Okatee/Colleton River Estuary is characterized by multiple residual eddies. Driven by the periodic tidal forcing, this estuarine system features a chaotic water transport process. Numerous residual eddies around the barrier complex in the Colleton River likely enhance the water exchange between the Okatee/Colleton River Estuary and the outer Broad River. A sensitivity study of flooding speed to the slope of the inter-tidal zone suggests that the saltmarsh bathymetry considerably influences the water elevation near low slack water but not on the maximum water coverage area at high slack water.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Hofmann, A. F., F. J. R. Meysman, K. Soetaert y J. J. Middelburg. "Factors governing the pH in a heterotrophic, turbid, tidal estuary". Biogeosciences Discussions 6, n.º 1 (7 de enero de 2009): 197–240. http://dx.doi.org/10.5194/bgd-6-197-2009.

Texto completo

Resumen

Abstract. A method to quantify the influence of kinetically modelled biogeochemical processes on the pH of an ecosystem with time variable acid-base dissociation constants is presented and applied to the heterotrophic, turbid Scheldt estuary (SW Netherlands, N Belgium). Nitrification is identified as the main process governing the pH profile of this estuary, while CO2 degassing and advective-dispersive transport "buffer" the effect of nitrification. CO2 degassing accounts for the largest proton turnover per year in the whole estuary. There is a clear inverse correlation between oxygen turnover and proton turnover. The main driver of long-term changes in the mean estuarine pH from 2001 to 2004 is a changing freshwater flow which influences the pH "directly" via [∑CO2] and [TA] and to a significant amount also "indirectly" via [∑NH4+] and the nitrification rates in the estuary.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Nitsche, Frank O., Robin Bell, Suzanne M. Carbotte, William B. F. Ryan y Roger Flood. "Process-related classification of acoustic data from the Hudson River Estuary". Marine Geology 209, n.º 1-4 (agosto de 2004): 131–45. http://dx.doi.org/10.1016/j.margeo.2004.05.023.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Kuang, Cuiping, Huidi Liang, Jie Gu, Tsungchow Su, Xute Zhao, Hongling Song, Yue Ma y Zhichao Dong. "Morphological process of a restored estuary downstream of a tidal barrier". Ocean & Coastal Management 138 (marzo de 2017): 111–23. http://dx.doi.org/10.1016/j.ocecoaman.2017.01.012.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Hongxia, Ming, Zan Shuaijun, Liu Jiwen, Su Jie, Ren Kaijia, Lin Jiannan, Chen Quanrui, Shi Yinyin, Shi Tingting y Fan Jingfeng. "Promoting the denitrification process by heavy metals in Liaohe Estuary sediment". Marine Pollution Bulletin 203 (junio de 2024): 116408. http://dx.doi.org/10.1016/j.marpolbul.2024.116408.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Haron, Nuryazmeen Farhan y Wardah Tahir. "Physical Model of Estuarine Salinity Intrusion into Rivers: A Review". Advanced Materials Research 905 (abril de 2014): 348–52. http://dx.doi.org/10.4028/www.scientific.net/amr.905.348.

Texto completo

Resumen

This paper reviews the physical models that had been used in order to conduct the experiment of estuarine salinity intrusion into rivers. Several studies used the physical models to get a better understanding of the estuary salinity mixing process and salt-wedge estuary characteristics along the flume. Besides, the laboratory investigations using the physical model also useful for verification purposes as discussed by previous researchers.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Kurnosova, Anna S. y M. A. Shulgina. "Hydrochemical conditions and phytoplankton in the Kievka estuary (Japan Sea) with calculation of primary production by phosphorus utilization". Izvestiya TINRO 203, n.º 4 (26 de diciembre de 2023): 961–75. http://dx.doi.org/10.26428/1606-9919-2023-203-961-975.

Texto completo

Resumen

Spatial distribution of chemical parameters, as concentration of dissolved inorganic phosphorus (DIP), inorganic silica, nitrite nitrogen, nitrate nitrogen, ammonium nitrogen, total iron, dissolved oxygen, and biochemical oxygen demand (BOD5) is considered together with species composition, abundance and biomass of phytoplankton on the data of complex survey conducted in the estuary of the Kievka River in May 2020, with special attention to DIP and phytoplankton variations along the salinity gradient in the zone of mixing fresh and saline waters. In the lower Kievka, phytoplankton was studied for the first time. The phytoplankon biomass varied from 0.05 to 0.21 g/m3, proportional to changes in primary production calculated from the DIP balance in the river water moving downstream through the estuary (from 0.02 to 0.23 g/m3km). The highest production and the highest biomass were found in the upper part of the external estuary. The water of Kievka River was initially poor in nutrients, so primary production in its estuary was supported by DIP regenerated in the process of organic matter mineralization in the internal estuary.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Spieckermann, M., A. Gröngröft, M. Karrasch, A. Neumann y A. Eschenbach. "Oxygen Consumption of Resuspended Sediments of the Upper Elbe Estuary: Process Identification and Prognosis". Aquatic Geochemistry 28, n.º 1 (30 de noviembre de 2021): 1–25. http://dx.doi.org/10.1007/s10498-021-09401-6.

Texto completo

Resumen

AbstractThe resuspension of sediment leads to an increased release of nutrients and organic substances into the overlying water column, which can have a negative effect on the oxygen budget. Especially in the warmer months with a lower oxygen saturation and higher biological activity, the oxygen content can reach critical thresholds in estuaries like the upper Elbe estuary. Many studies have dealt with the nutrient fluxes that occur during a resuspension event. However, the sediment properties that influence the oxygen consumption potential (OCP) and the different biochemical processes have not been examined in detail. To fill this gap, we investigated the biogeochemical composition, texture, and OCP of sediments at 21 locations as well as the temporal variability within one location for a period of 2 years (monthly sampling) in the upper Elbe estuary. The OCP of sediments during a seven-day resuspension event can be described by the processes of sulphate formation, nitrification, and mineralisation. Chlorophyll, total nitrogen (Ntotal), and total organic carbon showed the highest correlations with the OCP. Based on these correlations, we developed a prognosis model to calculate the OCP for the upper Elbe estuary with a single sediment parameter (Ntotal). The model is well suited to calculate the oxygen consumption of resuspended sediments in the Hamburg port area during the relevant warmer months and shows a normalised root mean squared error of < 0.11 ± 0.13. Thus, the effect of maintenance measures such as water injection dredging and ship-induced wave on the oxygen budget of the water can be calculated.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Mubarak, M., R. Rifardi, A. Riyadi, A. Sulaiman, D. Yoswati y M. A. Wibowo. "On the Salinity Distribution Induced Mixing at the Mouth of the Estuary". IOP Conference Series: Earth and Environmental Science 1118, n.º 1 (1 de diciembre de 2022): 012068. http://dx.doi.org/10.1088/1755-1315/1118/1/012068.

Texto completo

Resumen

Abstract Salinity is an essential parameter in estuaries because it determines the mixing process and distribution of biota in the estuary ecosystem. In the paper, we investigate the dynamics of salinity distribution in the Dumai estuary. Salinity and tidal data observation were carried out during the transitional season around the mouth of the estuary. We get the salinity time series data in a tidal cycle. We observed that the Formzhal number is about 0.239, indicating that the tidal type in Dumai estuary waters is mixed directional, tending to double a day, with the highest and lowest tides in the Dumai estuary being 1.26 and 0.47 m, respectively. The salinity variability due to tides was studied by harmonic analysis, while the spatiotemporal distribution was studied using an analytical solution developed by previous researchers. The results show the presence of time lag between tidal elevation and salinity variation. Low tide and salinity, which indicate the effect of river discharge, are significant. This study further indicated that high salinity occurs during strong mixing conditions. It implied that the high salinity from the offshore entrance to shallower waters allowed for mixing processes. This paper ends with a comprehensive discussion of the vertical distribution of salinity at the mouth of the estuary.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Kim, Sung-Bo y Doo-Pyo Kim. "Influence of Precipitation Conditions and Discharge Rates of River Estuary Barrages on Geomorphological Changes in an Estuarine Area". Applied Sciences 13, n.º 17 (26 de agosto de 2023): 9661. http://dx.doi.org/10.3390/app13179661.

Texto completo

Resumen

Changes in coastal topography can affect the ecological environment and marine industries. In this study, we analyzed the patterns and causes of changes in shoreline and undersea topography in the Nakdong River estuary in the southeast of Republic of Korea using depth and shoreline surveys of the estuary, as well as data on discharge, suspended sediments, and precipitation in the Nakdong River basin. The results showed that erosion and sedimentation occurred repeatedly owing to complex factors such as the discharge of the estuary and invasion by open sea waves. However, no clear unilateral trend was observed. Unlike previous survey data, a large amount of erosion occurred in the second half of 2020. Previously, sedimentation was the main process, but erosion occurred rapidly, which was observed in the summer of 2020 when the erosion was three times higher than that in other periods owing to the severe rainy season and torrential rains for over a month. In addition, regarding the flow rate and force of the river water outflow, the amount of discharge increased rapidly, causing erosion. Moreover, a strong typhoon in the summer of 2020 affected the topography of the estuary.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Khutornoi, Serhii, Mikhail O. Son y Yuriy Kvach. "First record of two fish species (Actinopterygii) in the Sukhyi Lyman, northwestern Black Sea, Ukraine". Acta Ichthyologica et Piscatoria 53 (12 de octubre de 2023): 157–62. http://dx.doi.org/10.3897/aiep.53.111525.

Texto completo

Resumen

Two new fish species were recorded while monitoring the fish fauna of Sukhyi Lyman (or Sukhyi Estuary), an estuary in the northwestern Black Sea (Ukraine) close to the marine port of Chornomorsk. A single pumpkinseed, Lepomis gibbosus (Linnaeus, 1758), was observed in May 1999, followed by numerous observations in May 2021, while a single peacock blenny, Salaria pavo (Risso, 1810), was photographed during snorkeling observations in September 2021. The estuary is a known hub for invasive alien species and other neobionts due to the presence of the marine port. The new population of pumpkinseed, a North American invasive species, in the estuary represents the next stage in the species’ ongoing expansion along the Ukrainian Black Sea coast. Likewise, the appearance of the peacock blenny represents the latest stage in the “Mediterranization” of the Black Sea, a process that has been ongoing over the last several thousand years.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

MEDEIROS DE CARVALHO, ALEXANDRE, VANDA CLAUDINO-SALES, FRANCISCO GLEIDSON DA COSTA GASTÃO, MILIANA TEIXEIRA DE OLIVEIRA, ELAINE DE SOUSA AGUIAR, DEBORA MARIA PATRÍCIO SOUSA y LIDRIANA DE SOUZA PINHEIRO. "ANTHROPOGENIC IMPACTS ON THE MORPHOLOGICAL EVOLUTION OF THE PACOTI ESTUARY, NORTHEAST BRAZIL". William Morris Davis - Revista de Geomorfologia 3, n.º 1 (26 de julio de 2022): 1–13. http://dx.doi.org/10.48025/issn2675-6900.v3n1.2022.142.

Texto completo

Resumen

The problem of anthropogenic occupation on the banks of estuaries and rivers has been a factor of concern and frequently addressed around the world. In the State of Ceará, this problem has been persistent, despite the reasonable environmental legislation dealing with this issue. Along the Pacoti River Estuary, this problem was addressed in this study and added to the analysis of the wind action in the evolution of this coastal environment. Thus, direct and indirect methods were applied, mainly based on field work and remote sensing based in the use of tools from a GIS platform. The results show persistent and continuous participation of aeolian activity, notably dunes migration, in the evolution process of this estuary. Additionally, human interference over 63 years, whether in the form of exploitation of natural resources and/or urban occupation on the banks of the estuary and in the possible area of expansion of this environment, has produced serious environmental damage and restricted the natural area of this important coastal ecosystem. This process of environmental degradation was largely accelerated from the occupation of the area to the east of the estuary by the Beach Park development, and to the west by the Alphaville Residential Condominium.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Febrianti, I., R. Ratianingsih y J. W. Puspita. "PERUBAHAN DISTRIBUSI MERKURI (Hg) TERHADAP WAKTU DI SEDIMEN SUNGAI POBOYA". JURNAL ILMIAH MATEMATIKA DAN TERAPAN 15, n.º 1 (14 de mayo de 2018): 86–97. http://dx.doi.org/10.22487/2540766x.2018.v15.i1.10205.

Texto completo

Resumen

Poboya is illegal gold mining area at Palu City. The amalgamate process of gold extraction is prepared traditionally using mercury. Tailing of this process which contains mercury is throwed away to the ground. The mercury contain will infiltrate to the soil water and later on pollute Poboya’s river. Related to the mercury that categorized as dangerous material, this research purposes to investigate the mercury distribution changing at Poboya’s river sediment. The mercury distribution changing is investigated by modify the advection-diffusion equation model. The model was completed by the initial conditions and Neumann boundary conditions. To get the numerical solutions, it is used a numerical scheme namely Duffort Frankel finite difference method for the second derivative, and Center Scheme for the first derivative. The solution represents the mercury distribution changing with respect to time at the Poboya’s river sediment. The simulation result explains that 0,0521 ppm mercury is distributed from the upper bound (current source) observation domain following the sediment direction (to estuary) caused by the advection process and decreased due to the diffusion process. For , the mecury was distributed 0,00285 m to the estuary direction with the mercury concentration is 0,005 ppm, until , mercury was distributed 0,00832 m to estuary with mercury concentration is 0,005 ppm. In fact that at the estuary (lower bound), the 0,0244 ppm mercury that was already deposited will be diffused in an opposite direction. The advection process and the low initial mercury concentration, makes the reached distribution distance is no longer far comparing to the opposited mercury distribution. For the mercury was distributed 0,000822 m to the upper direction with mercury concentration is 0,005 ppm, until , the mercury was distributed 0,000873 m with mercury concentration is 0,005 ppm

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Dong, Liang F., Cindy J. Smith, Sokratis Papaspyrou, Andrew Stott, A. Mark Osborn y David B. Nedwell. "Changes in Benthic Denitrification, Nitrate Ammonification, and Anammox Process Rates and Nitrate and Nitrite Reductase Gene Abundances along an Estuarine Nutrient Gradient (the Colne Estuary, United Kingdom)". Applied and Environmental Microbiology 75, n.º 10 (20 de marzo de 2009): 3171–79. http://dx.doi.org/10.1128/aem.02511-08.

Texto completo

Resumen

ABSTRACT Estuarine sediments are the location for significant bacterial removal of anthropogenically derived inorganic nitrogen, in particular nitrate, from the aquatic environment. In this study, rates of benthic denitrification (DN), dissimilatory nitrate reduction to ammonium (DNRA), and anammox (AN) at three sites along a nitrate concentration gradient in the Colne estuary, United Kingdom, were determined, and the numbers of functional genes (narG, napA, nirS, and nrfA) and corresponding transcripts encoding enzymes mediating nitrate reduction were determined by reverse transcription-quantitative PCR. In situ rates of DN and DNRA decreased toward the estuary mouth, with the findings from slurry experiments suggesting that the potential for DNRA increased while the DN potential decreased as nitrate concentrations declined. AN was detected only at the estuary head, accounting for ∼30% of N2 formation, with 16S rRNA genes from anammox-related bacteria also detected only at this site. Numbers of narG genes declined along the estuary, while napA gene numbers were stable, suggesting that NAP-mediated nitrate reduction remained important at low nitrate concentrations. nirS gene numbers (as indicators of DN) also decreased along the estuary, whereas nrfA (an indicator for DNRA) was detected only at the two uppermost sites. Similarly, nitrate and nitrite reductase gene transcripts were detected only at the top two sites. A regression analysis of log(n + 1) process rate data and log(n + 1) mean gene abundances showed significant relationships between DN and nirS and between DNRA and nrfA. Although these log-log relationships indicate an underlying relationship between the genetic potential for nitrate reduction and the corresponding process activity, fine-scale environmentally induced changes in rates of nitrate reduction are likely to be controlled at cellular and protein levels.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Zhang, X. Y., X. Chen, H. Deng, Y. Du y H. Y. Jin. "Absorption features of chromophoric dissolved organic matter (CDOM) and tracing implication for dissolved organic carbon (DOC) in Changjiang Estuary, China". Biogeosciences Discussions 10, n.º 7 (19 de julio de 2013): 12217–50. http://dx.doi.org/10.5194/bgd-10-12217-2013.

Texto completo

Resumen

Abstract. Chromophoric dissolved organic matter (CDOM) represents the light absorbing fraction of dissolved organic carbon (DOC). Studies have shown that the optical properties of CDOM can be used to infer the distribution and diffusion characteristics of DOC in the estuary and coastal zone. The inversion of DOC concentrations from remote sensing has been implemented in certain regions. In this study we investigate the potential of tracing DOC from CDOM by the measurement of DOC, absorption spectrum of CDOM, Chla concentration, suspended sediment (SS), and salinity from cruises in different seasons around the Changjiang estuary. Our results show that around the Changjiang estuary the absorption coefficients of CDOM in general have the similar spatial and temporal characteristics as that of DOC, but the strength of the correlation between CDOM and DOC varies locally and seasonally. The input of pollutants from outside the estuary, the bloom of phytoplankton in spring, re-suspension of deposited sediment, and light bleaching all contribute to the local and seasonal variation of the correlation between DOC and CDOM. An inversion model for the determination of DOC from CDOM is established, but the stability of model parameters and its application in different environments need further study. We find that relative to the absorption coefficient of CDOM, the fitted parameters of the absorption spectrum of DOM are better indictors for the composition of DOC. In addition, it is found that the terrestrial input of DOC to Changjiang estuary is a typical two-stage dilution process instead of a linear diffusion process.

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Park, Sangjun y Yongsik Sin. "Artificial Neural Network (ANN) Modeling Analysis of Algal Blooms in an Estuary with Episodic and Anthropogenic Freshwater Inputs". Applied Sciences 11, n.º 15 (27 de julio de 2021): 6921. http://dx.doi.org/10.3390/app11156921.

Texto completo

Resumen

The Youngsan River estuary, located on the southwest coast of South Korea, has transitioned from a natural to an artificial estuary since dike construction in 1981 separated freshwater and seawater zones. This artificial transition has induced changes in the physical properties and circulation within the estuary, which has led to hypoxia and algal blooms. In this study, an artificial neural network (ANN) model was employed to simulate phytoplankton variations, including algal blooms and size fractions based on chlorophyll a, using data obtained by long-term monitoring (2008–2018) of the seawater zone of the Youngsan River estuary. The model was validated through statistical analyses, and the validated model was used to determine the contribution of the environmental factors on size-fractionated phytoplankton variations. The statistical validation of the model showed extremely low sum square error (SSE ≤ 0.0003) and root mean square error (RMSE ≤ 0.0173) values, with R2 ≥ 0.9952. The accuracy of the model predictions was high, despite the considerable irregularity and wide range of phytoplankton variations in the estuary. With respect to phytoplankton size structure, the contribution of seasonal environmental factors such as water temperature and solar radiation was high for net-sized chlorophyll a, whereas the contribution of factors such as freshwater discharge and salinity was high for nano-sized chlorophyll a, which includes typical harmful algae. Notably, because the Youngsan River estuary is influenced by a monsoon climate—characterized by high precipitation in summer—the contribution of freshwater discharge to harmful algal blooms is predicted to increase during this period. Our results suggest that the ANN model can be an important tool for understanding the influence of freshwater discharge, which is essential for managing algal blooms and maintaining the ecosystem health of altered estuaries.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Hill, Erin M., Brien A. Nicolau y Paul V. Zimba. "History of Water and Habitat Improvement in the Nueces Estuary, Texas, USA". Texas Water Journal 2, n.º 1 (20 de diciembre de 2011): 97–111. http://dx.doi.org/10.21423/twj.v2i1.2104.

Texto completo

Resumen

Reservoir impoundments in the Nueces watershed (Texas, USA) have reduced Nueces River flows to the coast by more than 50% since the 1980s. Reductions in freshwater inflows prompted state and local managers, along with scientists, to embark on a 3-decade process of ecosystem-based restoration and habitat improvement in the Nueces Estuary. Current management efforts in the estuary have increased freshwater flow to the Rincon Bayou and habitat has been protected from land acquisition in the Nueces Delta. Restoring freshwater flow and acquiring land in the Nueces Delta was not easily accomplished but has been successful through the efforts of federal, state, local agencies, and nongovernmental organizations. This paper also describes mitigation activities that have taken place in the Nueces Estuary. Citation: EM Hill, BA Nicolau, PV Zimba. 2011. History of water and habitat improvement in the Nueces estuary, Texas, USA. Texas Water Journal. 2(1):97-111. Available from: https://doi.org/10.21423/twj.v2i1.2104.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Austin, Timothy, Ana Vila-Concejo, Andrew Short y Roshanka Ranasinghe. "A Multi-Scale Conceptual Model of Flood-Tide Delta Morphodynamics in Micro-Tidal Estuaries". Geosciences 8, n.º 9 (29 de agosto de 2018): 324. http://dx.doi.org/10.3390/geosciences8090324.

Texto completo

Resumen

Wave and tide induced sediment transport pathways and rates govern the morphological evolution of estuarine systems. An understanding of the morphodynamics of these systems is required to maintain their commercial, biological and recreational value. The morphodynamics of Port Stephens estuary, a micro-tidal estuary located on a wave dominated southeast coast of Australia were investigated using bathymetric surveys and current velocity data from several locations over the estuary. This provided detailed insight into the rates and direction of movement for the main sedimentary features of the system, and how these features interact with the processes that drive their evolution. We used these findings to develop a conceptual model for estuarine morphodynamics that accounts for fair weather and storm conditions. Our model explains how sediment eroded from the estuarine beaches is trapped by the adjacent flood-tide delta. The model is applicable to fetch-limited estuaries that do not have offshore sources of sediment, where the tidal currents are weak in relation to the incident ocean waves, and that have a wide, stable entrance through which ocean waves can propagate into the estuary. The model is multi-scale in that it encapsulates both short-term and local process, and large scale evolution of an estuary; therefore, it represents a tool that may be used in developing sustainable estuary management strategies.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Ortiz-Araya, Scarleth, Jonathan Chacón-Guzmán, Rigoberto Víquez-Portugués y Jeffrey A. Sibaja-Cordero. "Estructura espacial y temporal de la ictiofauna del Estero de Tamarindo, Parque Nacional Marino Las Baulas, Costa Rica". Revista de Biología Tropical 66, n.º 1-1 (1 de abril de 2018): 255. http://dx.doi.org/10.15517/rbt.v66i1.33298.

Texto completo

Resumen

Abstract: Spatial and temporal structure of the ichthyofauna of the Estuary of Tamarindo, Las Baulas National Marine Park, Costa Rica. Fish communities in mangrove areas have an ecological and socio-economic importance. The management in this kind of habitat is based on the data information about spatial and temporal patterns. The main goal of the study is determinate the spatial and temporal structure of the ichthic community from Tamarindo mangrove area. Six samplings trips were conducted from August 2009 to June 2010, at five mangrove stations using four different fishing gear. Also, environmental variates were recording (temperature, oxygen, salinity, pH, and water transparency). A total of 1357 individuals belonging to 59 species of 28 families were identified. Carangidae and Lutjanidae were more richness families, and the most abundant were Poecilidae, Mugilidae and Clupeidae. Poeciliopsis elongata was the most abundant species. Temporally, the diversity reached a minimum of 1.55 in December and a maximum of 1.96 in April. The richness presented a minimum of 22 species in February and a maximum of 25 in December. Spatially, the diversity reached a minimum of 1.96 in the mouth of the estuary and a maximum of 2.79 in mid estuary; the richness a minimum of 24 species inner the estuary and a maximum of 30 at mid estuary. Additionally, a temporal pattern of succession of species was determined. The fish community shows change in the similarity in their species composition from the mouth to the inner part of the estuary. At inner of the estuary the abundance was low, in contrast with the richness, diversity and equitability. Finally, nursery process for some key species for fisheries occurs in this estuary; made it fragile and susceptible to pollution and anthropogenic impacts, because their short mangrove area and shallow depth. Rev. Biol. Trop. 66(Suppl. 1): S255-S268. Epub 2018 April 01.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Kusuda, T., T. Umita, K. Koga, T. Futawatari y Y. Awaya. "Erosional Process of Cohesive Sediments". Water Science and Technology 17, n.º 6-7 (1 de junio de 1985): 891–901. http://dx.doi.org/10.2166/wst.1985.0188.

Texto completo

Resumen

Tests on erosion of the cohesive sediments in the Chikugo estuary in Japan were conducted. The results indicate that the decrease in the rate of erosion at constant shear stresses is caused rapidly 20 to 30 minutes after the start of tests and that tue decrease is caused by the increase in the solid fraction and the yield value of the seaiment remaining uneroded due to shear stress. In order to simulate the erosion process of sediments, a model in which the increase in the yield value of sediment is assumed to be proportional to the integration value of the absolute value of the sediment velocity gradient with respect to time was developed. The simulation based on this model is shown to be available to estimate the amount of sediments eroded in the erosional process of cohesive sediments.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Fahimah, Nurul, Annisa Dwi Damayanti, Venny Ulya Bunga y Haryo Mubiarto. "PROFIL VERTIKAL DAN HORIZONTAL PARAMETER SALINITAS, DHL, DAN TDS BERDASARKAN VARIASI MUSIMAN DI ESTUARI SUNGAI CITARUM". OSEANA 46, n.º 1 (30 de abril de 2021): 1–12. http://dx.doi.org/10.14203/oseana.2021.vol.46no.1.99.

Texto completo

Resumen

Salinity, electrical conductivity (EC), and Total Dissolved Solid (TDS) are parameters that pose an important role in the distributions of environmental pollution substances in the estuary. The difference in salinity, EC, and TDS concentration vertically (based on the depth in the water column) and horizontally (based on the distance from the estuary mouth) will affect the process of pollutant’s transportation and transformation in the estuary. On the other hand, seasonal variations will also affect parameters. Therefore, the information related to the vertical and horizontal profiles of salinity and other parameters based on seasonal variations is necessary to study. The purpose of this study is to analyze the vertical profile and horizontal-vertical of salinity, EC, and TDS concentrations during the rainy season and dry season in the estuary of Citarum River. This research was conducted in April 2018 (rainy season) and August 2018 (dry season) when the low tide. The measurement of salinity, EC, and TDS was directly conducted in the field using a conductivity meter. The results show that the concentration level of salinity, EC, and TDS showed a vertical and horizontal difference in the estuary of the Citarum River. In addition, there are differences in the concentration of salinity, electrical conductivity, TDS in the rainy season and dry season in the estuary of the Citarum River. The level of TDS has a linear relationship between salinity and electrical conductivity, with a value of R2 >95%.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Hu, Dechao, Min Wang, Shiming Yao y Zhongwu Jin. "Study on the Spillover of Sediment during Typical Tidal Processes in the Yangtze Estuary Using a High-Resolution Numerical Model". Journal of Marine Science and Engineering 7, n.º 11 (1 de noviembre de 2019): 390. http://dx.doi.org/10.3390/jmse7110390.

Texto completo

Resumen

Because of special morphologies and complex runoff–tide interactions, the landward floodtide flows in Yangtze Estuary are observed to spill over from the North to the South Branches, carrying a lot of sediment. To quantitatively clarify the spillover problem, a two-dimensional numerical model using a high-resolution channel-refined unstructured grid is developed for the entire Yangtze Estuary from Datong to river mouths (620 km) and part of the East Sea. The developed model ensures a good description of the river-coast-ocean coupling, the irregular boundaries, and local river regimes in the Yangtze Estuary. In tests, the simulated histories of the tidal level, depth-averaged velocity, and sediment concentration agree well with field data. The spillover of sediment in the Yangtze Estuary is studied using the condition of a spring and a neap tide in dry seasons. For a representative cross-section in the upper reach of the North Branch (QLG), the difference of the cross-sectional sediment flux (CSSF) between floodtide and ebbtide durations is 43.85–11.26 × 104 t/day, accounting for 37.5–34.9% of the landward floodtide CSSF. The mechanics of sediment spillover in Yangtze Estuary are clarified in terms of a successive process comprising the source, transport, and drainage of the spillover sediment.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Moore, C. G. "Meiofauna of the industrialised estuary and Firth of Forth, Scotland". Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 93, n.º 3-4 (1987): 415–30. http://dx.doi.org/10.1017/s0269727000006850.

Texto completo

Resumen

SynopsisKnowledge concerning the meiofauna of the Forth is reviewed and extended by presentation of the results of new surveys of the intertidal and subtidal provinces of the estuary. Most of the published information concerns the influence of sewage pollution on shores of the firth. Before 1979, the meiofaunal communities of sandy beaches along the Edinburgh coastline exhibited reduced species richness, although certain taxa displayed enhanced densities. Improvements in the sewage treatment process have initiated a phase of meiofaunal recovery.In the estuary the salinity regime plays a key role in the determination of species composition, although the influence of local changes in sediment type and stability is recognised. Meiofaunal communities of lower shore mudflats in different salinity zones of the estuary are described. Pollution plays a major modifying role. In the upper reaches of the estuary, which suffer oxygen depletion in summer, only nematodes and oligochaetes were recorded in the oligohaline zone and impoverished nematode and copepod faunas in the mesohaline zone. In the polyhaline zone discharges from the industrialised region around Grangemouth modify meiofaunal community structure over an extensive area of mudflat. The subtidal meiofauna of the lower estuary is briefly described, particularly with respect to the copepods. Impoverishment again occurs in the vicinity of Grangemouth.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Wong, Kuo-Chuin. "Numerical Simulation of the Exchange Process within a Shallow Bar-Built Estuary". Estuaries 16, n.º 2 (junio de 1993): 335. http://dx.doi.org/10.2307/1352506.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Díez-Minguito, M., A. Baquerizo, M. Ortega-Sánchez, G. Navarro y M. A. Losada. "Tide transformation in the Guadalquivir estuary (SW Spain) and process-based zonation". Journal of Geophysical Research: Oceans 117, n.º C3 (marzo de 2012): n/a. http://dx.doi.org/10.1029/2011jc007344.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Sandeen, Lawrence R., Jeffrey D. Wetherington, David R. Blye y Rao Sankarmanchi. "APPLICATION OF THE DQO PROCESS TO THE DELAWARE ESTUARY PCB TMDL PROGRAM". Proceedings of the Water Environment Federation 2005, n.º 3 (1 de enero de 2005): 192–211. http://dx.doi.org/10.2175/193864705783967034.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Gong, Wenping, Zhongyuan Lin, Yunzhen Chen, Zhaoyun Chen y Heng Zhang. "Effect of winds and waves on salt intrusion in the Pearl River estuary". Ocean Science 14, n.º 1 (28 de febrero de 2018): 139–59. http://dx.doi.org/10.5194/os-14-139-2018.

Texto completo

Resumen

Abstract. Salt intrusion in the Pearl River estuary (PRE) is a dynamic process that is influenced by a range of factors and to date, few studies have examined the effects of winds and waves on salt intrusion in the PRE. We investigate these effects using the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system applied to the PRE. After careful validation, the model is used for a series of diagnostic simulations. It is revealed that the local wind considerably strengthens the salt intrusion by lowering the water level in the eastern part of the estuary and increasing the bottom landward flow. The remote wind increases the water mixing on the continental shelf, elevates the water level on the shelf and in the PRE and pumps saltier shelf water into the estuary by Ekman transport. Enhancement of the salt intrusion is comparable between the remote and local winds. Waves decrease the salt intrusion by increasing the water mixing. Sensitivity analysis shows that the axial down-estuary wind, is most efficient in driving increases in salt intrusion via wind straining effect.

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Shi, Jian, Chaofeng Tong, Jinhai Zheng, Chi Zhang y Xiangyu Gao. "Kelvin-Helmholtz Billows Induced by Shear Instability along the North Passage of the Yangtze River Estuary, China". Journal of Marine Science and Engineering 7, n.º 4 (2 de abril de 2019): 92. http://dx.doi.org/10.3390/jmse7040092.

Texto completo

Resumen

Kelvin-Helmholtz (K-H) instability plays a significant role in mixing. To investigate the existence of K-H instability along the North Passage of the Yangtze River Estuary, the non-hydrostatic model NHWAVE is utilized to simulate the fresh-salt water mixing process along the North Passage of the Yangtze River Estuary. Using high horizontal resolution, the structure of K-H billows have been successfully captured within the Lower Reach of the North Passage. The K-H instability occurs between the max flood and high-water slack. The duration and length scale of the K-H billows highly depends on the local interaction between fresh-water discharge and tide. The horizontal length scale of the instability is about 60 m, similar to the observations in other estuaries. In the vertical direction, the K-H billows exist within the pycnocline with length scale ranging from 6 to 7 m. The timescale of the billows is approximate 6 min. By analyzing the changes of potential energy during the mixing process, results show that the existence of K-H instability induces intense vertical mixing, which can greatly increase mixing efficiency in the North Passage of the Yangtze River Estuary.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Rusmana, Iman y David B. Nedwell. "Denitrifier Still Has the Important Role in Nitrate Reduction to N2 Although It is Not the Predominant Population in the Estuarine Bacterial Community of Nitrate Reducing Bacteria". HAYATI Journal of Biosciences 31, n.º 4 (6 de marzo de 2024): 630–40. http://dx.doi.org/10.4308/hjb.31.4.630-640.

Texto completo

Resumen

Denitrification and nitrate-ammonification are the responsible processes for nitrate removal in the estuaries. Temperature, nitrate and organic carbon availability are key factors controlling a rate of the nitrate reduction processes. This mixed cultures chemostat study investigates the competition ability and their nitrate reduction end-products of the bacteria isolated from an estuary at different temperatures. This study will help us to understand the seasonal nitrate reduction processes in an estuary. The experiments showed that a nitrate-ammonifier was the predominant process in the steady-state chemostat at high temperature. While a facultative denitrifier-nitrate ammonifier was the predominant process at low temperature. However, the main end products of nitrate reduction at high temperature were up to 61% N2 indicating a denitrifier still had an important role in the end products of nitrate reduction in the estuary. The data also showed that a nitrite respiring bacterium reduced nitrite to N2, that responsible for approximately 6-9% of total N2 produced in the culture. This study confirmed that nitrate ammonifiers out-compete denitrifiers at high temperature, however, denitrifiers still had an important role in end products of nitrate reduction.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Dalrino, Mukhlis y Elvi Roza Syofyan. "Model Numerik 1D Penggerusan Endapan di Mulut Muara dengan Metode Beda Hingga". Jurnal Ilmiah Poli Rekayasa 10, n.º 1 (15 de octubre de 2014): 10. http://dx.doi.org/10.30630/jipr.10.1.52.

Texto completo

Resumen

Sedimentation at estuary river have potency to cause floods because the narrowing of estuary as outlet. Sedimentation process can be caused by the so small river discharge at dry season so that cannot to flushing the sediment that happened at estuary mouth. When the rains arrive, river discharge which starting to big shall no long castaway to sea freely, so that causes floods in headwaters. Numerical simulation by using finite different method with Preissmann implicit scheme conducted to see ability of river discharge in early the rains to flushing the sediment in estuary mouth. Simulation was done at river with sediment elevation at + 4.00 m in estuary mouth. Boundary condition in the form of discharge hydrograph in early the rains at upstream boundary and also critical water surface elevation in sediment top and sea level at downstream boundary applied at model to see behavior of sediment transport and change of profile at bottom channel that happened. Simulation result show with 24 hours floods charge in early the rains, sediment volume of flushed equal to 20,52 %, with elevation reside at + 3,179 m. Sediment will fully under sea-water face after 9 days simulation. Change of upriver discharge and tidal elevation at downstream will influence to speed of stream that happened. By the end of simulation, the bottom profile of channel influenced of tide.

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Bluteau, Cynthia Evelyn, Peter S. Galbraith, Daniel Bourgault, Vincent Villeneuve y Jean-Éric Tremblay. "Winter observations alter the seasonal perspectives of the nutrient transport pathways into the lower St. Lawrence Estuary". Ocean Science 17, n.º 5 (28 de octubre de 2021): 1509–25. http://dx.doi.org/10.5194/os-17-1509-2021.

Texto completo

Resumen

Abstract. The St. Lawrence Estuary connects the Great Lakes with the Atlantic Ocean. The accepted view, based on summer conditions, is that the estuary's surface layer receives its nutrient supply from vertical mixing processes. This mixing is caused by the estuarine circulation and tides interacting with the topography at the head of the Laurentian Channel. During winter when ice forms, historical process-based studies have been limited in scope. Winter monitoring has been typically confined to vertical profiles of salinity and temperature as well as near-surface water samples collected from a helicopter for nutrient analysis. In 2018, however, the Canadian Coast Guard approved a science team to sample in tandem with its ice-breaking and ship escorting operations. This opportunistic sampling provided the first winter turbulence observations, which covered the largest spatial extent ever measured during any season within the St. Lawrence Estuary and the Gulf of St. Lawrence. The nitrate enrichment from tidal mixing resulted in an upward nitrate flux of about 30 nmol m−2 s−1, comparable to summer values obtained at the same tidal phase. Further downstream, deep nutrient-rich water from the gulf was mixed into the subsurface nutrient-poor layer at a rate more than an order of magnitude smaller than at the head. These fluxes were compared to the nutrient load of the upstream St. Lawrence River. Contrary to previous assumptions, fluvial nitrate inputs are the most significant source of nitrate in the estuary. Nitrate loads from vertical mixing processes would only exceed those from fluvial sources at the end of summer when fluvial inputs reach their annual minimum.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Barrera Crespo, Pedro D., Erik Mosselman, Alessio Giardino, Anke Becker, Willem Ottevanger, Mohamed Nabi y Mijail Arias-Hidalgo. "Sediment budget analysis of the Guayas River using a process-based model". Hydrology and Earth System Sciences 23, n.º 6 (28 de junio de 2019): 2763–78. http://dx.doi.org/10.5194/hess-23-2763-2019.

Texto completo

Resumen

Abstract. The equatorial Daule and Babahoyo rivers meet and combine into the tidal Guayas River, which flows into the largest estuary on the Pacific coast of South America. The city of Guayaquil, located along the Guayas, is the main port of Ecuador but, at the same time, the planet's fourth most vulnerable city to future flooding due to climate change. Sedimentation, which has increased in recent years, is seen as one of the factors contributing to the risk of flooding. The cause of this sedimentation is the subject of the current research. We used the process-based Delft3D FM model to assess the dominant processes in the river and the effects that past interventions along the river and its estuary have had on the overall sediment budget. Additionally, a simulation including sea level rise was used in order to understand the possible future impact of climate change on the sediment budget. Results indicate an increase in tidal asymmetry due to land reclamation and a decrease in episodic flushing by river floods due to upstream dam construction. These processes have induced an increased import of marine sediment potentially responsible for the observed sedimentation. This is in contrast with the local perception of the problem, which ascribes sedimentation to deforestation in the upper catchment. Only the deposition of silt and clay in connected stagnant water bodies could perhaps be ascribed to upstream deforestation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Hofmann, A. F., J. J. Middelburg, K. Soetaert y F. J. R. Meysman. "pH modelling in aquatic systems with time-variable acid-base dissociation constants applied to the turbid, tidal Scheldt estuary". Biogeosciences 6, n.º 8 (7 de agosto de 2009): 1539–61. http://dx.doi.org/10.5194/bg-6-1539-2009.

Texto completo

Resumen

Abstract. A new pH modelling approach is presented that explicitly quantifies the influence of biogeochemical processes on proton cycling and pH in an aquatic ecosystem, and which accounts for time variable acid-base dissociation constants. As a case study, the method is applied to investigate proton cycling and long-term pH trends in the Scheldt estuary (SW Netherlands, N Belgium). This analysis identifies the dominant biogeochemical processes involved in proton cycling in this heterotrophic, turbid estuary. Furthermore, information on the factors controlling the longitudinal pH profile along the estuary as well as long-term pH changes are obtained. Proton production by nitrification is identified as the principal biological process governing the pH. Its acidifying effect is mainly counteracted by proton consumption due to CO2 degassing. Overall, CO2 degassing generates the largest proton turnover in the whole estuary on a yearly basis. The main driver of long-term changes in the mean estuarine pH over the period 2001 to 2004 is the decreasing freshwater flow, which influences the pH directly via a decreasing supply of dissolved inorganic carbon and alkalinity, and also indirectly, via decreasing ammonia loadings and lower nitrification rates.

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Zhang, Wei, Shujie Lyu, Yuliang Zhu y Xiaowen Chen. "A Coupled Model of the 1D River Network and 3D Estuary Based on Hydrodynamics and Suspended Sediment Simulation". Journal of Applied Mathematics 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/798579.

Texto completo

Resumen

River networks and estuaries are very common in coastal areas. Runoff from the upper stream interacts with tidal current from open sea in these two systems, leading to a complex hydrodynamics process. Therefore, it is necessary to consider the two systems as a whole to study the flow and suspended sediment transport. Firstly, a 1D model is established in the Pearl River network and a 3D model is applied in its estuary. As sufficient mass exchanges between the river network and its estuary, a strict mathematical relationship of water level at the interfaces can be adopted to couple the 1D model with the 3D model. By doing so, the coupled model does not need to have common nested grids. The river network exchanges the suspended sediment with its estuary by adding the continuity conditions at the interfaces. The coupled model is, respectively, calibrated in the dry season and the wet season. The results demonstrate that the coupled model works excellently in simulating water level and discharge. Although there are more errors in simulating suspended sediment concentration due to some reasons, the coupled model is still good enough to evaluate the suspended sediment transport in river network and estuary systems.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Xie, Xiao, Ping Liang y Qiwen Qian. "Sub-Seasonal Prediction of Sea-Gale Processes in the Yangtze River Estuary of China". Atmosphere 14, n.º 4 (5 de abril de 2023): 682. http://dx.doi.org/10.3390/atmos14040682.

Texto completo

Resumen

The sea-gale process (SGP) is a significant and disastrous weather event for the marine industry. However, the sub-seasonal predictability of SGP remains unclear. In this study, we investigate the influence of low-frequency oscillation on SGP in the Yangtze River estuary from November to April, and its implications for sub-seasonal prediction. We noted that SGPs have a close relationship with the 10~30 day low-frequency component of the 10-m wind speed in the Yangtze River estuary, and typically occur during the peak phase of the low-frequency oscillation. The 10~30 day low-frequency oscillation of 10-m wind was found to be linked to the eastward propagation of extratropical Rossby waves from the North Atlantic across Europe to East Asia. This Rossby wave leads to the low-frequency oscillation of the Siberian high pressure and Japan Sea low pressure, which is indicative of the 10~30 day low-frequency oscillations of the 10-m wind speed in the Yangtze River Estuary. A sea-gale process index (SGPI) was constructed based on the low-frequency oscillation of the Siberian high and the Japan Sea low in order to predict SGPs at the sub-seasonal time scale. Hindcast and real-time forecasts showed that 2/3 of SGPs can be predicted with a leading time of 10~30 days, and that good sub-seasonal predictions of SGPs are connected with strong low-frequency oscillations at the initial forecast time. Therefore, SGPI can be adopted for the sub-seasonal prediction of SGPs in the Yangtze River Estuary.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Adilah, A. Kadir, Yusop Zulkifli, Z. Noor Zainura y Baharim N. Bakhiah. "Environmental Flow for Sungai Johor Estuary". E3S Web of Conferences 34 (2018): 02041. http://dx.doi.org/10.1051/e3sconf/20183402041.

Texto completo

Resumen

Sungai Johor estuary is a vital water body in the south of Johor and greatly affects the water quality in the Johor Straits. In the development of the hydrodynamic and water quality models for Sungai Johor estuary, the Environmental Fluid Dynamics Code (EFDC) model was selected. In this application, the EFDC hydrodynamic model was configured to simulate time varying surface elevation, velocity, salinity, and water temperature. The EFDC water quality model was configured to simulate dissolved oxygen (DO), dissolved organic carbon (DOC), chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N), nitrate nitrogen (NO3-N), phosphate (PO4), and Chlorophyll a. The hydrodynamic and water quality model calibration was performed utilizing a set of site specific data acquired in January 2008. The simulated water temperature, salinity and DO showed good and fairly good agreement with observations. The calculated correlation coefficients between computed and observed temperature and salinity were lower compared with the water level. Sensitivity analysis was performed on hydrodynamic and water quality models input parameters to quantify their impact on modeling results such as water surface elevation, salinity and dissolved oxygen concentration. It is anticipated and recommended that the development of this model be continued to synthesize additional field data into the modeling process.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Tengku Fadhlin Tengku Mohmed Noor Izam, Nuryazmeen Farhan Haron, Siti Nurhayati Mohd Ali, Noor Suraya Romali y Saerahany Legori Ibrahim. "Idealised Estuary Salinity-Morphology Effect Characterisation Investigation". Journal of Advanced Research in Applied Sciences and Engineering Technology 42, n.º 1 (26 de marzo de 2024): 93–103. http://dx.doi.org/10.37934/araset.42.1.93103.

Texto completo

Resumen

Estuaries are bodies of water along the coasts that are formed when fresh water from rivers flows into and mixes with salt water from the ocean. The density of seawater is greater than fresh water and it varies with salinity and temperature. Fresh water tends to float on top of seawater because of its lower density. Human-induced activities like the dredging of shipping lanes along the bottom estuarine, the dumping of industrial wastes into the water system, and shoreline development influence estuarine dynamics which include the mixing process. These activities lead to salinity changes and further adversely affect the estuarine ecosystem. The purpose of this research is to verify how salinity-morphology relations change in an estuarine system under various rainfall patterns, more specifically under extremely high rainfall conditions. The experiment that has been conducted studied the salinity-morphology relationships for a variety of rainfall patterns, most particularly for exceptionally high rainfall conditions, using an idealised channel. In the first part of this research, the morphology changes of the mixing between salt water (estuary) and freshwater (river) for different rainfall patterns, had been investigated in laboratory experiments. Fresh water was released from one end of the flume channel and overflowing over the weir at the other end. Meanwhile, salt water was represented by the red dye tracer released slowly through a weir and intruded horizontally to the upstream as a gravity current. In this experiment, an artificial roughened bed section was used as morphology change. The salinity pattern is plotted using Microsoft Excel. The salinity levels were measured at selected stations along the channel/longitudinal (x-axis), and also in transverse (y-axis) and vertical directions (z-axis) within the time duration. The observed salinity profile showed the difference in salinity level between heavy and light rain conditions with morphology effect where during heavy rain, the salinity level will decrease, hence, the existence of an artificial roughened bed section will affect the time taken for the process of mixing between salt water and fresh water.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Luan, Kuifeng, Hui Li, Jie Wang, Chunmei Gao, Yujia Pan, Weidong Zhu, Hang Xu, Zhenge Qiu y Cheng Qiu. "Quantitative Inversion Method of Surface Suspended Sand Concentration in Yangtze Estuary Based on Selected Hyperspectral Remote Sensing Bands". Sustainability 14, n.º 20 (12 de octubre de 2022): 13076. http://dx.doi.org/10.3390/su142013076.

Texto completo

Resumen

The distribution of the surface suspended sand concentration (SSSC) in the Yangtze River estuary is extremely complex. Therefore, effective methods are needed to improve the efficiency and accuracy of SSSC inversion. Hyperspectral remote sensing technology provides an effective technical means of accurately monitoring and quantitatively inverting SSSC. In this study, a new framework for the accurate inversion of the SSSC in the Yangtze River estuary using hyperspectral remote sensing is proposed. First, we quantitatively simulated water bodies with different SSSCs using sediment samples from the Yangtze River estuary, and analyzed the spectral characteristics of water bodies with different SSSCs. On this basis, we compared six spectral transformation forms, and selected the first derivative (FD) transformation as the optimal spectral transformation form. Subsequently, we compared two feature band extraction methods: the successive projections algorithm (SPA) and the competitive adaptive reweighted sampling (CARS) method. Then, the partial least squares regression (PLSR) model and back propagation (BP) neural network model were constructed. The BP neural network model was determined as the best inversion model. The new FD-CARS-BP framework was applied to the airborne hyperspectral data of the Yangtze estuary, with R2 of 0.9203, RPD of 4.5697, RMSE of 0.0339 kg/m3, and RMSE% of 8.55%, which are markedly higher than those of other framework combination forms, further verifying the effectiveness of the FD-CARS-BP framework in the quantitative inversion process of SSSC in the Yangtze estuary.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "Estuary process"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros