scholarly journals Sediment Distribution, Retention and Morphodynamic Analysis of a River-Dominated Deltaic System

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1341
Author(s):  
Ehab Meselhe ◽  
Kazi Sadid ◽  
Ashok Khadka
Keyword(s):  
Dynamic Equilibrium ◽  
River System ◽  
Channel Network ◽  
Sediment Distribution ◽  
Coastal Restoration ◽  
Coastal Land Loss ◽  
Overbank Flow ◽  
Wax Lake Delta ◽  
Coastal Land

River deltas have received considerable attention due to coastal land loss issues caused by subsidence, storms, and sea level rise. Improved understanding of deltaic processes and dynamics is vital to coastal restoration efforts. This paper describes the application of process-based morphodynamic models to a prograding river delta. The analysis focuses on the flow and sediment dynamics amongst the interconnected channel network of the delta. The models were validated against observations of velocity and sediment concentrations for the Wax Lake Delta (WLD) of the Atchafalaya River system in Louisiana, USA. The WLD provides an opportunity as a natural laboratory for studying the processes associated with river dominated deltaic growth. It includes a network of bifurcated channels that self-organize and dynamically adjust, as the delta grows seaward to the Gulf of Mexico. The model results for a flood event show that 47% of the flow exits the system as channelized flow and the remaining 53% exits as overbank flow. The fine sediment (silt and clay) distribution was proportional with water fluxes throughout the channel network, whereas sand distribution was influenced by geometric attributes (size, invert elevation, and alignment) of the distributary channels. The long-term deltaic growth predicted by the model compares well with the observations for the period 1998–2012. This paper provides insights on how the distribution of flow and sediment amongst the interconnected delta channels influences the morphodynamics of the delta to reach a dynamic equilibrium within this relatively young deltaic system.

Fish Habitat: Essential Fish Habitat and Rehabilitation

1999 ◽  
Keyword(s):  
Fish Habitat ◽  
Nursery Habitat ◽  
Estuarine Fish ◽  
Land Loss ◽  
Estuarine Habitat ◽  
Resource Managers ◽  
Coastal Land Loss ◽  
State And Local ◽  
Coastal Land

<em>Abstract.</em> —The magnitude of changes occurring in Louisiana’s estuaries creates a unique set of challenges in fish habitat management. Louisiana leads the nation in rate of coastal land loss, with some 70% of national losses. Both natural and anthropogenic factors are involved in coastal land loss in Louisiana: subsidence, erosion, sediment and freshwater deficits, channelization, and rising mean sea level. Disruption of the natural deltaic cycles of the Mississippi River has been particularly detrimental to estuarine fish habitat. Navigation and flood control needs have resulted in the near-total leveeing of the river, preventing normal overbank flooding, channel filling and switching, delta and subdelta development, and sediment nourishment of adjacent and down-current marshes. The resulting system is one in which the quantity and quality of estuarine habitat are linked to rapidly degrading wetland environments. Although the relative production value of subsiding marsh surfaces is often very high, this condition is not sustainable. Steep declines in fish production have been forecast for the next century. Federal, state, and local coastal restoration projects are attempting to address the loss of estuarine habitat with a number of techniques that may produce localized changes in fisheries production and distributions. Temporary resource displacements can result in increased harvest costs, and basin-scale changes may be particularly hard to accept for resource users who are satisfied with current conditions. Harvesters have demonstrated reluctance, and may lack the financial flexibility, to forfeit expected current catches for predicted enhancement of long-term fisheries production. In some instances, both sportfishers and commercial resource users have expressed concern over estuarine freshening and turbidity from restoration inputs from riverine sources. Additional public perception difficulties with restoration efforts arise from misunderstandings of the nature of estuarine functions, particularly of the importance of nursery habitat and of the value of low-salinity marshes as nursery habitat. Significant improvement in the outlook for estuarine fish habitat in Louisiana will require long-term and large-area vision from resource managers and the public.

Basic principles for assessing the safety of fish products from the ponds exposed to the influence of nuclear fuel cycle enterprises

2019 ◽  
pp. 106-114
Author(s):  
A. V. Trapeznikov ◽  
V. N. Trapeznikova ◽  
A. V. Korzhavin ◽  
V. N. Nikolkin ◽  
A. P. Plataev
Keyword(s):  
Fuel Cycle ◽  
Specific Activity ◽  
River System ◽  
Food Product ◽  
Human Consumption ◽  
Basic Principles ◽  
Fish Products ◽  
Permissible Levels ◽  
Irtysh River

Relevance. In connection with the development of nuclear energy, many aquatic ecosystems have been exposed to radioactive substances. Fish, as an element of biota, is capable to accumulate radionuclides. However, fish is a traditional food. The control of the technogenic radionuclides accumulation level in the ichthyofauna is an important link in ensuring human security.Intention. To analyze the long-term data on the content of long-lived technogenic radionuclides 90Sr and 137Cs in the ichthyofauna of the Ob-Irtysh river system for the period from 2004 to 2016 and Beloyarsky pond for the period from 1977 to 2018.Methodology. Fish as a food product was assessed according to two criteria: a) permissible levels of specific activity of radionuclides (SanPiN 2.3.2.1078-01); b) using the indicator of conformity B and the uncertainty of its definition В (GOST 32161-2013 and GOST 32163-2013).Results and Discussion. Fish of all species that live in the river Tetcha, is not suitable for food use according to the criteria of SanPiN 2.3.2.1078-01, GOST 32161-2013 and GOST 32163-2013. The fish of the Ob-Irtysh river system, the habitat of which is located outside the Tetcha, meets the requirements for fish products. In the period from 1977 to 1989 in the Beloyarsk pond the accumulations of technogenic radionuclides in fish in quantities exceeding sanitary and hygienic standards were possible. Currently, the fish of the Beloyarsky pond fully complies with the sanitary and hygienic requirements for the radiation factor and is safe for human consumption.Conclusion. In the ponds exposed to the atomic energy enterprises, it is necessary to continuously monitor the content of long-lived technogenic radionuclides in fish and assess their amount in accordance with the requirements of SanPiN 2.3.2.1078-01 and using the conformity indicator В and the uncertainty of its determination В. 

River Quality Models for Consent Setting in England and Wales

1989 ◽  
Vol 21 (8-9) ◽  
pp. 1015-1024 ◽  
Author(s):  
C. P. Crockett ◽  
R. W. Crabtree ◽  
I. D. Cluckie
Keyword(s):  
River System ◽  
Quality Model ◽  
Catchment Scale ◽  
Quality Models ◽  
England And Wales ◽  
Future Developments ◽  
Statistical Framework ◽  
River Quality ◽  
National Approach

In England and Wales the placing of effluent discharge consents within a statistical framework has led to the development of a new hybrid type of river quality model. Such catchment scale consent models have a stochastic component for the generation of model inputs and a deterministic component to route them through the river system. This paper reviews and compares the existing approaches for consent modelling used by various Water Authorities. A number of possible future developments are suggested including the potential need for a national approach to the review and setting of long term consents.

scholarly journals Technical note: Assessing gas equilibration systems for continuous <i>p</i>CO<sub>2</sub> measurements in inland waters

2016 ◽  
Vol 13 (13) ◽  
pp. 3915-3930 ◽  
Author(s):  
Tae Kyung Yoon ◽  
Hyojin Jin ◽  
Neung-Hwan Oh ◽  
Ji-Hyung Park
Keyword(s):  
River System ◽  
Fast Response ◽  
Technical Note ◽  
Spatial Variations ◽  
Detection Range ◽  
Measurement Systems ◽  
Co2 Sensor ◽  
Continuous Measurements ◽  
Membrane Biofouling

Abstract. High-frequency continuous measurements of the partial pressure of CO2 (pCO2) are crucial for constraining the spatiotemporal dynamics of CO2 emissions from inland water systems. However, direct measurements of pCO2 are scarce, and no systematic comparisons have been conducted on the suitability of the widely used measurement systems for continuous underway or long-term deployment in various field conditions. We compared spray- and marble-type equilibrators and a membrane-enclosed CO2 sensor to assess their suitability for continuous long-term or underway pCO2 measurements in an urbanized river system in Korea. Both equilibrators had a shorter response time compared with the membrane-enclosed sensor, and could capture large spatial variations of pCO2 during a transect study along a highly urbanized river reach. The membrane-enclosed sensor based on passive equilibration provided comparable underway measurements along the river sections where pCO2 varied within the sensor detection range. When deployed in a eutrophic river site, the membrane-enclosed sensor was able to detect large diel variations in pCO2. However, biofouling on the membrane could reduce the accuracy of the measurement during long deployments exceeding several days. The overall results suggest that the fast response of the equilibrator systems facilitates capturing large spatial variations in pCO2 during short underway measurements. However, the attendant technical challenges of these systems, such as clogging and desiccant maintenance, have to be addressed carefully to enable their long-term deployment. The membrane-enclosed sensor would be suitable as an alternative tool for long-term continuous measurements if membrane biofouling could be overcome by appropriate antifouling measures such as copper mesh coverings.

scholarly journals Long-term persistence of crAss-like phage crAss001 is associated with phase variation in Bacteroides intestinalis

2020 ◽  
Author(s):  
Andrey N Shkoporov ◽  
Ekaterina V Khokhlova ◽  
Niamh Stephens ◽  
Cara Hueston ◽  
Samuel Seymour ◽  
...  
Keyword(s):  
Dynamic Equilibrium ◽  
Phase Variation ◽  
Carrier State ◽  
Human Gut ◽  
Rapid Phase ◽  
Host Interaction ◽  
Infected Cells ◽  
Phage Sensitivity

The crAss-like phages are ubiquitous and highly abundant members of the human gut virome that infect commensal bacteria of the order Bacteroidales. Although incapable of classical lysogeny, these viruses demonstrate unexplained long-term persistence in the human gut microbiome, dominating the virome in some individuals. Here we demonstrate that rapid phase variation of alternate capsular polysaccharides plays an important role in dynamic equilibrium between phage sensitivity and resistance in B. intestinalis cultures, allowing phage and bacteria to multiply in parallel. The data also suggests the role of concomitant phage persistence mechanisms associated with delayed lysis of infected cells, such as carrier state infection. From an ecological and evolutionary standpoint this type of phage-host interaction is consistent with the Piggyback-the-Winner model, which suggests a preference towards lysogenic or other 'benign' forms of phage infection when the host is stably present at high abundance.

scholarly journals Integration of Indonesian Coffee Markets with World Coffee Markets

2021 ◽  
Vol 2 (1) ◽  
pp. 33
Author(s):  
Haposan Orlando Napitupulu ◽  
Ana Arifatus Sa'diyah ◽  
Farah Mutiara
Keyword(s):  
Time Series Data ◽  
Dynamic Equilibrium ◽  
Secondary Data ◽  
Series Data ◽  
Short Term ◽  
Robusta Coffee ◽  
Long Run ◽  
Relationship Of ◽  
Coffee Markets

This study aims to analyze the integration of the Arabica and Robusta coffee markets in Indonesia with world coffee prices. The study uses secondary data in the form of annual time series data during the period 1985 - 2015. The study uses the VECM analysis method. This method explains the relationship of long-term dynamic equilibrium and short-term equilibrium in a system of equations. The analysis shows that Indonesian and world Arabica coffee is not integrated in the long term or the short term. In Robusta coffee VECM estimation analysis shows that there is a significant value at the 10% level in a long-term relationship with a value of 0.08579, which means that there is a short-term relationship between world Robusta coffee prices and domestic Robusta coffee prices in the previous year, but no relationship in the long run.

From the Punjab to Pattala

2020 ◽  
pp. 234-264
Author(s):  
Waldemar Heckel
Keyword(s):  
Monsoon Season ◽  
River System ◽  
Indus River ◽  
The World ◽  
End Of The World ◽  
The Ganges ◽  
Direct Attack

The campaign in the Punjab saw Alexander, supported by his Indian ally Taxiles, attack Porus, who lived beyond the Hydaspes River. The battle, at the beginning of the monsoon season, involved a division of the Macedonian forces. One part faced Porus at the river crossing, where the current and the elephants in the Indian army made a direct attack virtually impossible. Alexander took a portion of his army and marched upstream. Once across the river, he drew Porus away from his defensive position and defeated the Indian ruler in a battle fought primarily by cavalry, although the Macedonian pikemen inflicted injuries on the elephants, which became a danger to their own troops. After the Hydaspes victory, Alexander advanced to the Hyphasis (Beas), where the army refused to cross in order to march to the Ganges. The whole episode was contrived, since Alexander clearly had no intention of going farther east. His failure to reach the eastern end of the world was thus attributed to the timidity and war-weariness of his soldiers. During the descent of the Indus river system, Alexander received a near-fatal wound at the hands of the Mallians. Once he recovered, Alexander conducted a series of bloody massacres as he sailed to the mouth of the Indus and accomplished his goal of sailing out into the ocean. Although the Indian campaign was by far the bloodiest of the expedition, there was little long-term gain from the conquest.

Long‐term observation of fish community in streams inside and outside road construction of Teshio River system, northern Hokkaido, Japan

2020 ◽  
Vol 35 (6) ◽  
pp. 986-993
Author(s):  
Yoshiyuki Umatani ◽  
Atsushi Okuda ◽  
Eishi Fujito ◽  
Toshiya Yoshida ◽  
Fuyuki Satoh ◽  
...  
Keyword(s):  
Fish Community ◽  
Road Construction ◽  
River System ◽  
Long Term Observation
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