scholarly journals Impact of River Dams on Littoral Cells Located Adjacent to the River Mouth

2021 ◽  
Vol 16 (3) ◽  
pp. 942-952
Author(s):  
KAMAL NAG
Keyword(s):  
Image Processing ◽  
Suspended Sediment ◽  
River Mouth ◽  
Temporal Analysis ◽  
Sediment Budget ◽  
Sediment Supply ◽  
Water Diversion ◽  
Littoral Cells ◽  
Geomorphological Changes ◽  
The Impact

Terrestrial sediment is a major source of sediment to all coasts. Suspended sediment is carried away by the rivers and supplied to the coast to maintain sediment budget. The construction of dams across the rivers arrest sediment behind it and affect the sediment budget of littoral cells along the coast. Reduction in sediment supply induces ecological as well as geomorphological changes along the shoreline. Coastal erosion may accelerate due to reduced sediment influx. With the growing number of cross-river dams and water diversion projects, it has become a major concern before the scientific community to measure, understand and find solutions to multi-fold geo-environmental problems that are arising out of river damming. The present study aims to find out the impact of dams on the coast. It examines how the changes in the suspended sediment supply of an Indian river impact the coast in terms of loss of area due to erosion. Temporal analysis of geomorphological changes along the shoreline in relation to sediment influx holds immense importance to coastal management essential for the sustainable life and livelihood of coastal communities. Scientific investigation into the impact of river dams on the coastal environment is likely to provide a strong ground to reconsider the way present basin development projects function. Areal changes in littoral sediment cells adjacent to the river mouth have been quantified and correlated with changes in sediment influx. Changes along the shorelines have been detected through multispectral satellite images of Landsat belonging to different dates. Image processing and quantification of changes have been performed in QGIS 3.14 “Pi” platform. Virtual raster, raster calculator, field calculator and other required tools in QGIS were used during image processing.

scholarly journals Morphological Changes of the Lower Ping and Chao Phraya Rivers, North and Central Thailand: Flood and Coastal Equilibrium Analyses

2019 ◽  
Vol 11 (1) ◽  
pp. 152-171 ◽  
Author(s):  
Nikhom Chaiwongsaen ◽  
Parisa Nimnate ◽  
Montri Choowong
Keyword(s):  
Morphological Changes ◽  
River Mouth ◽  
Sediment Supply ◽  
Gulf Of Thailand ◽  
River Bank ◽  
Water Storage Capacity ◽  
Rainfall Condition ◽  
Sand Bar ◽  
Geomorphological Changes ◽  
Chao Phraya River

Abstract The Chao Phraya River flows in the largest river basin of Thailand and represents one of the important agricultural and industrial areas in Southeast Asia. The Ping River is one major upstream branch flowing down slope southwardly, joining the Chao Phraya River in the low-lying central plain and ending its course at the Gulf of Thailand. Surprisingly, the overflow occurs frequently and rapidly at the Lower Ping River where channel slope is high, and in particular area, sand-choked is extensively observed, even in normal rainfall condition. In contrary, at the downstream part, the erosion of river bank and shoreline around the mouth of Chao Phraya River has been spatially increasing in place where there should be a massive sediment supply to form a delta. Here we use Landsat imageries taken in 1987, 1997, 2007 and 2017 to analyze geomorphological changes of rivers. Results show that both rivers have undergone the rapid decreasing of water storage capacity and increasing of sand bar areas in river embayment. The total emerged sand bar area in the Lower Ping River increases from 1987 to 2017 up to 28.8 km2. The excessive trapped bed sediments deposition along the upper reaches is responsible for the shallower of river embankment leading to rapid overflow during flooding. At the Chao Phraya River mouth, a total of 18.8 km2 of the coastal area has been eroded from 1987 to 2017.This is caused by the reducing of sediment supply leading to non-equilibrium in the deltaic zone of the upper Gulf of Thailand. There are several possibility implications from this study involving construction of weir, in-channel sand mining, reservoir sedimentation and coastal erosion management.

scholarly journals Recent geomorphic evolution of the fan delta of the Mornos river, Greece: natural processes and human impacts

2007 ◽  
Vol 40 (4) ◽  
pp. 1538 ◽  
Author(s):  
E. Karymbalis ◽  
K. Gaki-Papanastassiou ◽  
H. Maroukian
Keyword(s):  
Human Impacts ◽  
River Mouth ◽  
Sediment Supply ◽  
Aerial Photographs ◽  
Natural Processes ◽  
Gulf Of Corinth ◽  
Fan Delta ◽  
Northern Side ◽  
The Impact ◽  
Comparative Examination

The Mornos river fan delta is located on the northern side of the western Gulf of Corinth is a Gilbert-type fan delta with an arcuate form characterised by the abundance of coarse sediments. In order to determine the processes which contributed in the configuration of the fan delta during the last two centuries a detailed geomorphic map was prepared depicting both the deltaic plain and the coastal zone features. Comparative examination of 1945, 1986 and 1998 aerial photographs and reliable maps of the last two centuries along with field observations detected recent changes of the fan delta. The construction of a dam in the upper reaches of the basin in 1980 has significantly decreased the sediment supply downstream and has slackened the growth of the fan delta. After 1980 the eastern distributary has been abandoned causing a 120 m retreat at the river mouth. Although a progradation rate of 4 m/year has been observed for the western active distributary in the period between 1945 and 1986, no remarkable changes have occurred since that period. Additionally, an assessment of the impact of the potential global future sea-level rise to the fan delta is attempted.

scholarly journals Suspended-Sediment Distribution Patterns in Tide-Dominated Estuaries on the Eastern Amazon Coast: Geomorphic Controls of Turbidity-Maxima Formation

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1568
Author(s):  
Vando J. C. Gomes ◽  
Nils E. Asp ◽  
Eduardo Siegle ◽  
José Diego Gomes ◽  
Ariane M. M. Silva ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Regional Climate ◽  
Strong Dependence ◽  
River Sediments ◽  
River Mouth ◽  
Sediment Supply ◽  
Amazon River ◽  
Sediment Delivery ◽  
Sediment Distribution ◽  
The World

In tide-dominated estuaries, maximum-turbidity zones (MTZs) are common and prominent features, characterized by a peak in suspended-sediment concentration (SSC) associated with estuarine processes. The Brazilian Amazon coast includes many estuaries, experiencing macrotidal conditions. MTZs are expected to occur and are crucial for sediment delivery to the longest continuous mangrove belt of the world. The area is under influence of the Amazon River plume (ARP), the main SSC source, as local rivers do not deliver substantial sediment supply. To assess the processes that allow the ARP to supply sediment to the estuaries and mangrove belt along the Amazon coast, the results from previous individual studies within five Amazon estuaries (Mocajuba, Taperaçu, Caeté, Urumajó and Gurupi) were compared with regards to SSC, salinity, morphology and tidal propagation. This comparison reinforces that these estuaries are subject to similar regional climate and tidal variations, but that their dynamics differ in terms of distance from the Amazon River mouth, importance of the local river sediment source, and morphology of the estuarine setting. The Urumajó, Caeté and Gurupi are hypersynchronous estuaries where perennial, classic MTZs are observed with SSC > 1 g·L−1. This type of estuary results in transport convergence and MTZ formation, which are suggested to be the main processes promoting mud accumulation in the Amazonian estuaries and therefore the main means of mud entrapment in the mangrove belt. The Mocajuba and the Taperaçu estuaries showed synchronous and hyposynchronous processes, respectively, and do not present classic MTZs. In these cases, the proximity to the ARP for the Mocajuba and highly connected tidal channels for the Taperaçu estuary, assure substantial mud supply into these estuaries. This study shows the strong dependence of the estuaries and mangrove belt on sediment supply from the ARP, helping to understand the fate of Amazon River sediments and providing insights into the mechanisms providing sediment to estuaries and mangroves around the world, especially under the influence of big rivers.

scholarly journals Climate change and human influences on sediment fluxes and the sediment budget of an urban delta: the example of the lower Rhine–Meuse delta distributary network

2021 ◽  
Vol 4 (1) ◽  
pp. 251-280
Author(s):  
J.R. Cox ◽  
F.E. Dunn ◽  
J.H. Nienhuis ◽  
M. van der Perk ◽  
M.G. Kleinhans
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Suspended Sediment ◽  
Sea Level ◽  
Sediment Budget ◽  
Sediment Supply ◽  
Climate Change Scenarios ◽  
Channel Network ◽  
Port Development ◽  
The Future

Deltas require sufficient sediment to maintain their land area and elevation in the face of relative sea-level rise. Understanding sediment budgets can help in managing and assessing delta resilience under future conditions. Here, we make a sediment budget for the distributary channel network of the Rhine–Meuse delta (RMD), the Netherlands, home to the Port of Rotterdam. We predict the future budget and distribution of suspended sediment to indicate the possible future state of the delta in 2050 and 2085. The influence of climate and anthropogenic effects on the fluvial and coastal boundaries was calculated for climate change scenarios, and the effects of future dredging on the budget were related to port development and accommodation of larger ships in inland ports. Suspended sediment rating curves and a 1D flow model were used to estimate the distribution of suspended sediment and projected erosion and sedimentation trends for branches. We forecast a negative sediment budget (net annual loss of sediment) for the delta as a whole, varying from −8 to −16 Mt/year in 2050 and −11 to −25 Mt/year by 2085, depending on the climate scenario and accumulated error. This sediment is unfavourably distributed: most will accrete in the northern part of the system and must consequently be removed by dredging for navigation. Meanwhile, vulnerable intertidal ecosystems will receive insufficient sediment to keep up with sea-level rise, and some channels will erode, endangering bank protection. Despite increased coastal import of sediment by estuarine processes and increased river sediment supply, extensive dredging for port development will cause a sediment deficit in the future.

scholarly journals A 2-D process-based model for suspended sediment dynamics: a first step towards ecological modeling

2015 ◽  
Vol 19 (6) ◽  
pp. 2837-2857 ◽  
Author(s):  
F. M. Achete ◽  
M. van der Wegen ◽  
D. Roelvink ◽  
B. Jaffe
Keyword(s):  
Suspended Sediment ◽  
San Francisco ◽  
Complex Geometry ◽  
Transport Model ◽  
Sediment Dynamics ◽  
Sediment Supply ◽  
Model Parameters ◽  
Habitat Conditions ◽  
A Chain ◽  
The Impact

Abstract. In estuaries suspended sediment concentration (SSC) is one of the most important contributors to turbidity, which influences habitat conditions and ecological functions of the system. Sediment dynamics differs depending on sediment supply and hydrodynamic forcing conditions that vary over space and over time. A robust sediment transport model is a first step in developing a chain of models enabling simulations of contaminants, phytoplankton and habitat conditions. This works aims to determine turbidity levels in the complex-geometry delta of the San Francisco estuary using a process-based approach (Delft3D Flexible Mesh software). Our approach includes a detailed calibration against measured SSC levels, a sensitivity analysis on model parameters and the determination of a yearly sediment budget as well as an assessment of model results in terms of turbidity levels for a single year, water year (WY) 2011. Model results show that our process-based approach is a valuable tool in assessing sediment dynamics and their related ecological parameters over a range of spatial and temporal scales. The model may act as the base model for a chain of ecological models assessing the impact of climate change and management scenarios. Here we present a modeling approach that, with limited data, produces reliable predictions and can be useful for estuaries without a large amount of processes data.

scholarly journals Centennial to Multi-Decadal Morphology Change and Sediment Budget Alteration with Consideration of the Impacts of the 2011 Tohoku Earthquake Tsunami along the Nobiru Coast, Japan

2021 ◽  
Vol 9 (3) ◽  
pp. 265
Author(s):  
Nguyen Trong Hiep ◽  
Hitoshi Tanaka ◽  
Nguyen Xuan Tinh
Keyword(s):  
Morphological Changes ◽  
River Mouth ◽  
Tohoku Earthquake ◽  
Sediment Budget ◽  
Sediment Supply ◽  
The 2011 Tohoku Earthquake ◽  
Morphology Change ◽  
Longshore Transport ◽  
Sediment Input ◽  
The Government

The Nobiru Coast is situated on the southwest of the Ishinomaki Bay. The 2011 Great East Japan Tsunami severely devastated the Nobiru Coast and the adjacent Naruse River mouth. In this study, an investigation was conducted based on the available historic maps and images combined with in situ surveys that revealed the century-to-decade morphology change and sediment budget alteration in the Nobiru Coast. During the past two centuries, the longshore transport on the northeast coast and sediment supply from the Naruse River were the principal sediment supply onto the Nobiru Coast and the estimated annual net sediment input into the coast was 87,000 m3/y. Until several decades ago, the construction of the Ishinomaki Port and the erosion preventing constructions (breakwaters, headlands) along the Ohmagari Coast on the northeast areas caused a dramatic reduction of longshore transport to the Nobiru Coast. Hence, the net sediment input fell to 46,000 m3/y. After the tsunami, the sediment input was further reduced to 29,000 m3/y and this loss was closely related to the intruded sediment into the Naruse River. The outcomes of this study are highly valuable for the government authorities to manage the long-term coastal and riverine morphological changes after the 2011 tsunami.

THE INITIAL RESULTS OF THE SUSPENDED SEDIMENT DYNAMICS DURING THE DRY SEASON IN THE HAU RIVER MOUTH AREA

2017 ◽  
Vol 17 (2) ◽  
Author(s):  
Nguyen Ngoc Tien ◽  
Dinh Van Uu ◽  
Nguyen Tho Sao ◽  
Do Huy Cuong ◽  
Nguyen Trung Thanh ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
River Mouth ◽  
Dry Season ◽  
Sediment Dynamics ◽  
Mouth Area ◽  
River Mouth Area ◽  
Initial Results

Estimating OLED Display Device Lifetime from pixel and screen brightness and its application

2019 ◽  
Vol 2019 (1) ◽  
pp. 331-338 ◽  
Author(s):  
Jérémie Gerhardt ◽  
Michael E. Miller ◽  
Hyunjin Yoo ◽  
Tara Akhavan
Keyword(s):  
Image Processing ◽  
Power Consumption ◽  
Model Parameters ◽  
Display Device ◽  
Image Processing Algorithm ◽  
Pixel Value ◽  
Device Lifetime ◽  
The Impact ◽  
Oled Display

In this paper we discuss a model to estimate the power consumption and lifetime (LT) of an OLED display based on its pixel value and the brightness setting of the screen (scbr). This model is used to illustrate the effect of OLED aging on display color characteristics. Model parameters are based on power consumption measurement of a given display for a number of pixel and scbr combinations. OLED LT is often given for the most stressful display operating situation, i.e. white image at maximum scbr, but having the ability to predict the LT for other configurations can be meaningful to estimate the impact and quality of new image processing algorithms. After explaining our model we present a use case to illustrate how we use it to evaluate the impact of an image processing algorithm for brightness adaptation.

scholarly journals Watershed Suspended Sediment Supply and Potential Impacts of Dam Removals for an Estuary

2021 ◽  
Author(s):  
David K. Ralston ◽  
Brian Yellen ◽  
Jonathan D. Woodruff
Keyword(s):  
Suspended Sediment ◽  
River Estuary ◽  
Dam Removal ◽  
Hudson River ◽  
Sediment Traps ◽  
Sediment Supply ◽  
Watershed Area ◽  
Natural Lakes ◽  
Sediment Deposits ◽  
Dam Removals

AbstractObservations and modeling are used to assess potential impacts of sediment releases due to dam removals on the Hudson River estuary. Watershed sediment loads are calculated based on sediment-discharge rating curves for gauges covering 80% of the watershed area. The annual average sediment load to the estuary is 1.2 Mt, of which about 0.6 Mt comes from side tributaries. Sediment yield varies inversely with watershed area, with regional trends that are consistent with substrate erodibility. Geophysical and sedimentological surveys in seven subwatersheds of the Lower Hudson were conducted to estimate the mass and composition of sediment trapped behind dams. Impoundments were classified as (1) active sediment traps, (2) run-of-river sites not actively trapping sediment, and (3) dammed natural lakes and spring-fed ponds. Based on this categorization and impoundment attributes from a dam inventory database, the total mass of impounded sediment in the Lower Hudson watershed is estimated as 4.9 ± 1.9 Mt. This represents about 4 years of annual watershed supply, which is small compared with some individual dam removals and is not practically available given current dam removal rates. More than half of dams impound drainage areas less than 1 km2, and play little role in downstream sediment supply. In modeling of a simulated dam removal, suspended sediment in the estuary increases modestly near the source during discharge events, but otherwise effects on suspended sediment are minimal. Fine-grained sediment deposits broadly along the estuary and coarser sediment deposits near the source, with transport distance inversely related to settling velocity.

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