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.

MORPHOLOGICAL CHANGES OF THE RIVER MOUTH SAND BAR AT THE KUMANO RIVER

2021 ◽  
Vol 77 (2) ◽  
pp. I_523-I_528
Author(s):  
Junya YAMAMOTO ◽  
Makoto NAKAMICHI ◽  
Masaaki HASHIMOTO ◽  
Jun KANETO ◽  
Tomokazu HIROSAWA ◽  
...  
Keyword(s):  
Morphological Changes ◽  
River Mouth ◽  
Sand Bar

scholarly journals INVESTIGATION OF MORPHOLOGICAL CHANGE AT THE CUA DAI RIVER MOUTH THROUGH SATELLITE IMAGE ANALYSIS

2017 ◽  
pp. 9
Author(s):  
Hitoshi Tanaka ◽  
Vo Cong Hoang ◽  
Viet Trung Nguyen
Keyword(s):  
Image Analysis ◽  
Morphological Change ◽  
Satellite Image ◽  
River Mouth ◽  
Sediment Supply ◽  
Landsat Images ◽  
River Bank ◽  
Main River Channel ◽  
Decadal Scale ◽  
The Right

Morphology of Cua Dai River mouth and adjacent sandy beaches in Hoi An City, Vietnam has been being eroded severely in recent years. Based on analysis of Landsat images, the long-term evolution, decadal scale, of morphology at this area since 1975 to 2015 is discussed. Morphology of river mouth in the period from 1975 to 1991 is highly similar to one in the period from 2003 to 2015, long sandspit on the left side and cuspate shoreline (cuspate foreland) on the right side, whereas the formation of double sandspit and welding between them after that was observed in the period from 1995 to 2002. From the characteristics of morphological change, there are three types of river mouth formed during the 40-year long period are classified. In addition, results of image analysis also indicate that the right bank of river shifted southward about 250 m. This is corresponding to the period with elongation of sandspit on the left after welding from offshore sandbar. The tip of cuspate shoreline on the right side was also observed to move to the south during the period that right river bank shifting southward. Besides the reduction of sediment supply to the river mouth, the shifting to south of main river channel diverting more sediment deposit on the right side of the river mouth, resulting in the erosion of the Cua Dai Beach on the left side became more serious. Countermeasure, which diverts more sediment to the left side, is highly required. Detailed effectiveness and magnitude of this structure can be evaluated based on numerical simulation.

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.

Coastal development in southwestern Bangladesh: understanding the interplay between storms and sea level rise

2021 ◽  
pp. 030913332110461
Author(s):  
Md. Masidul Haque ◽  
Manoj Kumer Ghosh ◽  
Koichi Hoyanagi
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Satellite Images ◽  
Morphological Changes ◽  
Coastal Region ◽  
River Mouth ◽  
Sedimentary Facies ◽  
Sediment Supply ◽  
Coastal Development ◽  
Silty Sand

Sea-level rise and sediment supply have influenced coastal morphology and sedimentation on Bangladesh’s southwestern Ganges‐Brahmaputra‐Meghna (GBM) delta coast. Satellite images and geological core from the Haringhata coastal region were analyzed to explain the morphological changes and to understand the influences on deposits. The results derived from satellite images indicate that the southern coastline experienced a retreat that ranges between 2.3 and 2.9 km. In contrast, the eastern and western coastline advanced. The erosion and accretion ratio was 0.29 from 1977 to 1989, while the ratio was higher 2.90–4.77 from 1989 to 2020. Two sedimentary facies were identified using 130 cm thick successions. A parallel to wavy laminated bluish gray mud facies of deeper part was deposited in a marine-influenced environment. A planar to hummocky cross stratified, gray to grayish white silty sand facies of storm overwash deposits overlies the mud facies with sharp contacts. Unimodal to bimodal grain distributions of sandy sediments suggest two sources: sand derived from the beach and mud carried by adjacent tidal rivers and resuspended offshore sediment. Coastline dynamics and sedimentation of the area were influenced by inequality of accommodation and sediment supply ratio in the river mouth. This occurs due to sea-level rise and deficit in upstream water and sediment discharge. Morphological change along the southwestern GBM delta coast was not only caused by wave energy, but also by rising sea levels which shifted sediment accommodation space landward.

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.

scholarly journals Macro-roughness model of bedrock–alluvial river morphodynamics

2015 ◽  
Vol 3 (1) ◽  
pp. 113-138 ◽  
Author(s):  
L. Zhang ◽  
G. Parker ◽  
C. P. Stark ◽  
T. Inoue ◽  
E. Viparelli ◽  
...  
Keyword(s):  
Fixed Bed ◽  
River Mouth ◽  
Steady State Solution ◽  
Bedload Transport ◽  
Spatiotemporal Variation ◽  
Sediment Supply ◽  
Complex Case ◽  
Upstream Migration ◽  
Major Advance ◽  
Bedrock Erosion

Abstract. The 1-D saltation–abrasion model of channel bedrock incision of Sklar and Dietrich (2004), in which the erosion rate is buffered by the surface area fraction of bedrock covered by alluvium, was a major advance over models that treat river erosion as a function of bed slope and drainage area. Their model is, however, limited because it calculates bed cover in terms of bedload sediment supply rather than local bedload transport. It implicitly assumes that as sediment supply from upstream changes, the transport rate adjusts instantaneously everywhere downstream to match. This assumption is not valid in general, and thus can give rise to unphysical consequences. Here we present a unified morphodynamic formulation of both channel incision and alluviation that specifically tracks the spatiotemporal variation in both bedload transport and alluvial thickness. It does so by relating the bedrock cover fraction to the ratio of alluvium thickness to bedrock macro-roughness, rather than to the ratio of bedload supply rate to capacity bedload transport. The new formulation (MRSAA) predicts waves of alluviation and rarification, in addition to bedrock erosion. Embedded in it are three physical processes: alluvial diffusion, fast downstream advection of alluvial disturbances, and slow upstream migration of incisional disturbances. Solutions of this formulation over a fixed bed are used to demonstrate the stripping of an initial alluvial cover, the emplacement of alluvial cover over an initially bare bed and the advection–diffusion of a sediment pulse over an alluvial bed. A solution for alluvial–incisional interaction in a channel with a basement undergoing net rock uplift shows how an impulsive increase in sediment supply can quickly and completely bury the bedrock under thick alluvium, thus blocking bedrock erosion. As the river responds to rock uplift or base level fall, the transition point separating an alluvial reach upstream from an alluvial–bedrock reach downstream migrates upstream in the form of a "hidden knickpoint". A tectonically more complex case of rock uplift subject to a localized zone of subsidence (graben) yields a steady-state solution that is not attainable with the original saltation–abrasion model. A solution for the case of bedrock–alluvial coevolution upstream of an alluviated river mouth illustrates how the bedrock surface can be progressively buried not far below the alluvium. Because the model tracks the spatiotemporal variation in both bedload transport and alluvial thickness, it is applicable to the study of the incisional response of a river subject to temporally varying sediment supply. It thus has the potential to capture the response of an alluvial–bedrock river to massive impulsive sediment inputs associated with landslides or debris flows.

The Chao Phraya River Basin: water quality and anthropogenic influences

2018 ◽  
Vol 19 (5) ◽  
pp. 1287-1294 ◽  
Author(s):  
Nuanchan Singkran ◽  
Pitchaya Anantawong ◽  
Naree Intharawichian ◽  
Karika Kunta
Keyword(s):  
Water Quality ◽  
Land Use ◽  
River Basin ◽  
River Mouth ◽  
Oxygen Demand ◽  
Quality Parameters ◽  
Paddy Fields ◽  
Coliform Bacteria ◽  
Wet Season ◽  
Chao Phraya River

Abstract Land use influences and trends in water quality parameters were determined for the Chao Phraya River, Thailand. Dissolved oxygen (DO), biochemical oxygen demand (BOD), and nitrate-nitrogen (NO3-N) showed significant trends (R2 ≥ 0.5) across the year, while total phosphorus (TP) and faecal coliform bacteria (FCB) showed significant trends only in the wet season. DO increased, but BOD, NO3-N, and TP decreased, from the lower section (river kilometres (rkm) 7–58 from the river mouth) through the middle section (rkm 58–143) to the upper section (rkm 143–379) of the river. Lead and mercury showed weak/no trends (R2 < 0.5). Based on the river section, major land use groups were a combination of urban and built-up areas (43%) and aquaculture (21%) in the lower river basin, paddy fields (56%) and urban and built-up areas (21%) in the middle river basin, and paddy fields (44%) and other agricultural areas (34%) in the upper river basin. Most water quality and land use attributes had significantly positive or negative correlations (at P ≤ 0.05) among each other. The river was in crisis because of high FCB concentrations. Serious measures are suggested to manage FCB and relevant human activities in the river basin.

Effects of episodic sediment supply on experimental step-pool channel morphology, bedload transport and channel stability

2021 ◽  
Author(s):  
Jiamei Wang ◽  
Marwan A. Hassan ◽  
Matteo Saletti ◽  
Xingyu Chen ◽  
Xudong Fu ◽  
...  
Keyword(s):  
Grain Size ◽  
Morphological Changes ◽  
Mass Movement ◽  
Channel Morphology ◽  
Bedload Transport ◽  
Sediment Supply ◽  
Primary Control ◽  
Channel Stability ◽  
Flume Experiments ◽  
Small Magnitude

<p>Steep step-pool streams are often coupled to adjacent hillslope, directly receiving episodic sediment supply from mass movement processes such as landslides and debris flows. The response of step-pool channels to the variations in sediment supply remains largely unexplored. We conducted flume experiments with a poorly sorted grain-size distribution in an 8%-steep, 5-m long flume with variable width at the University of British Columbia, to study the effects of episodic sediment supply on channel evolution. After a conditioning phase with no feed, the channel was subjected to sediment pulses of different magnitude and frequency under constant flow discharge. High-resolution data of hydraulics, bedload transport, bed surface grain size, and channel morphology were collected every 10-20 minutes and an additional time at the end of each pulse.</p><p>In response to sediment pulses, we recorded an increase in bedload transport rates, channel aggradation, bed surface fining, and continuous step formation and collapse. In between pulses, bedload rates dropped by several orders of magnitude, net erosion occurred, the bed surface gradually coarsened, and steps became more stable. The small-magnitude high-frequency pulses caused smaller but more frequent spikes in bedload transport, bed surface evolution, and thus step stability. Instead, the large-magnitude low-frequency pulses cause larger changes but provided a longer time for the channel to recover. This suggests that in step-pool channels pulse magnitude is a key control on channel rearrangement, while pulse frequency controls how fast and strong the recovery is.</p><p>The frequency and stability of steps varied as a function of local channel width, showing that channel geometry is a primary control on step formation and stability even under episodic sediment supply conditions. Instead, the effect of sediment pulses is less important because the total number and average survival time of steps were similar among runs with different pulses. The critical Shields stress decreased following sediment pulses, then increased immediately after, and fluctuated until the next pulse. The variations in sediment supply caused cycles in bedload transport rate, surface and bedload texture, thus controlling the variability in the threshold for motion.</p><p>Our results indicate that episodic sediment supply is a primary control on the evolution of step-pool channels, with sediment feed magnitude affecting mostly morphological changes, and sediment feed frequency controlling channel stability.</p>

Distribution and Potential Risk of Copper in Surface Sediments of Anping Harbor, Taiwan

2013 ◽  
Vol 376 ◽  
pp. 463-467
Author(s):  
Cheng Di Dong ◽  
Chih Feng Chen ◽  
Chiu Wen Chen
Keyword(s):  
Potential Risk ◽  
Municipal Wastewater ◽  
Risk Index ◽  
River Mouth ◽  
Potential Ecological Risk ◽  
River Bank ◽  
Ecological Risk Index ◽  
Sources Of Pollution ◽  
Accumulation Index ◽  
Geo Accumulation Index

This study was conducted using the data collected at the Anping Harbor, Taiwan to investigate and analyze Copper (Cu) contained in the sediments, and to evaluate the accumulation of Cr and the degree of its potential risk. The results show that samples collected at ten monitoring points contain 23380 mg/kg of Cu with an average of 114±101 mg/kg. The spatial distribution of Cu reveals that the Cu concentration is relatively high in the Bamboo River mouth region, and gradually diminishes toward the harbor region. This indicates that upstream industrial and municipal wastewater discharges along the river bank are major sources of pollution. Results from the enrichment factor and geo-accumulation index analyses imply that the Bamboo River mouth sediments can be characterized as severe enrichment and moderate to strong accumulation of Cu, respectively. However, results of potential ecological risk index indicate that the sediment has low ecological potential risk. The results can provide valuable information to developing future strategies for the management of river mouth and harbor.

scholarly journals Coastal morphological changes in the Red River Delta under increasing natural and anthropic stresses

2019 ◽  
Vol 2 (1) ◽  
pp. 51-71 ◽  
Author(s):  
Daidu Fan ◽  
Dac Ve Nguyen ◽  
Jianfeng Su ◽  
Vuong Van Bui ◽  
Dinh Lan Tran
Keyword(s):  
Coastal Erosion ◽  
Land Reclamation ◽  
Morphological Changes ◽  
River Delta ◽  
Sediment Supply ◽  
Red River ◽  
Coastal Protection ◽  
Mangrove Forests ◽  
Red River Delta ◽  
Sediment Redistribution

River deltas are the best place to study intense human–earth interactions and the resultant morphological changes and sedimentary records. The coastal evolution history of the Red River Delta (RRD) is examined by time-series analysis of multiple coastline locations. We find that spatiotemporal variation in seawall locations and vegetation lines are obviously site-specific due to intense human interference, while changes in 0 m isobaths are highly dependent on external stresses. Coastal erosion and deposition patterns are determined firstly by sediment inputs from different distributaries, and secondly by sediment redistribution with tides, waves, and longshore currents. The causes of chronic erosion along the Hai Hau coast include swift distributary channels, negligible sediment supply by the regional longshore current, and continuous sediment export by local wave-generated longshore and offshore currents. The area of intertidal flats decreased significantly due to land reclamation and decelerating coastal accretion. The area of mangrove forests decreased first due to human deforestation, and then increased gradually due to artificial plantation. Poorly designed coastal infrastructures may increase risks of coastal erosion and flooding disasters. More coastal sectors in the RRD may turn into erosion due to continuous decrease in riverine sediment discharges, deserving more attention on proper coastal protection and management.

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