scholarly journals EVOLUTION OF RIVER MOUTH DELTA -RESPONSES TO VARIABLE RIVER SEDIMENT DISCHARGE AND TO SHIFTING RIVER MOUTH OPENING-

2017 ◽  
Vol 73 (2) ◽  
pp. I_545-I_552
Author(s):  
Hitoshi TANAKA ◽  
Vo Cong HOANG ◽  
Dinh Van DUY ◽  
Yuta MITOBE ◽  
Nguyen Trung VIET
Keyword(s):  
River Sediment ◽  
Mouth Opening ◽  
River Mouth ◽  
Sediment Discharge

scholarly journals Assessing modern river sediment discharge to the ocean using satellite gravimetry

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Maxime Mouyen ◽  
Laurent Longuevergne ◽  
Philippe Steer ◽  
Alain Crave ◽  
Jean-Michel Lemoine ◽  
...  
Keyword(s):  
River Sediment ◽  
Sediment Discharge ◽  
Satellite Gravimetry

scholarly journals The effects of Thailand׳s Great Flood of 2011 on river sediment discharge in the upper Chao Phraya River basin, Thailand

2015 ◽  
Vol 30 (4) ◽  
pp. 328-337 ◽  
Author(s):  
Butsawan Bidorn ◽  
Seree Chanyotha ◽  
Stephen A. Kish ◽  
Joseph F. Donoghue ◽  
Komkrit Bidorn ◽  
...  
Keyword(s):  
River Basin ◽  
River Sediment ◽  
Sediment Discharge ◽  
Chao Phraya River

scholarly journals Sand Bypassing Methodology For Sustainable River Mouth Opening

2019 ◽  
Vol 8 (2S11) ◽  
pp. 2280-2284
Keyword(s):  
Sediment Transport ◽  
Tamil Nadu ◽  
Mouth Opening ◽  
River Mouth ◽  
The Other ◽  
Natural Sediment ◽  
Water Level Rise ◽  
Model Study ◽  
River Training ◽  
The Impact

River inlets along the Tamil Nadu coast remain mostly closed due to negligible fresh water flow and also due to various structures constructed near to the river inlet obstructing natural sediment transport. Excessive development of the sand spit also causes serious problems such as water level rise during floods and difficulty in navigation through river mouth. To reduce the impact of coastal area flooding and easy navigation it is necessary to keep the river mouth open. River training walls (RTW) are generally constructed to keep the river mouth open. Depending upon the sediment transport direction, sediments get deposited on one side of the RTW, while depleting the sediments from the other side. To prevent the sediment deposit from spilling over to river mouth, it is ideal to bypass the sand to the other side of the river mouth. This study analyses the methodologies for sand bypassing. A numerical model study has been carried out using DHI LITPACK to evaluate the sedimentation. The procedure of sand bypassing using pumps and pipe lines are discussed. Volume of sand bypassed, pump capacity, the number of Booster pumps to maintain critical velocity etc. can be determined based on the procedure discussed

Recent Evolution and Future Prediction of the Delta at the Yangtze River Mouth

2013 ◽  
Vol 353-356 ◽  
pp. 2699-2704 ◽  
Author(s):  
Ming Li ◽  
Yun Ping Yang ◽  
Yi Tian Li
Keyword(s):  
Mathematical Model ◽  
Yangtze River ◽  
River Mouth ◽  
Sediment Discharge ◽  
The Yangtze River ◽  
Discharge Data ◽  
One Dimensional ◽  
Water And Sediment ◽  
The Future ◽  
The One

In this study, an empirical curve describing the relation between erosion and deposition rate and water/sediment discharge was developed based on the recent evolution trend of the submerged delta at the Yangtze River Mouth, and the one-dimensional mathematical model for unsteady water-and sediment-transport was calibrated using the water and sediment discharge data after water impounding to predict the water and sediment discharge for the future 10 years and the future evolution of the submerged delta at the Yangtze River Mouth. The results showed that the 10 m and 20 m isobaths areas of the submerged delta changed with the water and sediment discharge from siltation to siltation slowing down to erosion. Siltation increased with large amount of rain received by the watershed during 1997-2000, while continuous retreat of erosion happened during 2000-2009. Using the one-dimensional mathematical model for river water and sediment calibrated and tested with data collected after impounding, the water and sediment discharges were calculated for Series 60 and 90, and its evolution in 2013-2022 was predicted for the delta. For Series 60, its 10 cm and 20 cm isobaths areas showed alternative scour and siltation, while the delta showed trends of erosion. For Series 90, its 10 m and 20 m isobaths showed substantial siltation in flood years. The water and sediment discharges since the Three Gorges Reservoirs was filled were lower than the calculated results for both Series 60 and 90. If the water and sediment discharges continue to decease, the delta will take an erosion trend.

scholarly journals The influence of xenobiotics in river sediment on the reproduction and survival of Daphnia magna, 1820, Straus

2012 ◽  
Vol 24 (2) ◽  
pp. 220-234 ◽  
Author(s):  
Silvana Pereira Gonçalves ◽  
Fabiane Lucheta ◽  
Viviane Kelin de Souza ◽  
Nara Regina Terra
Keyword(s):  
Daphnia Magna ◽  
Chronic Toxicity ◽  
Culture Medium ◽  
River Sediment ◽  
River Mouth ◽  
Reproductive Activity ◽  
Rainfall Index ◽  
Sources Of Pollution ◽  
South Of Brazil ◽  
Number Of Individuals

AIM: The Taquari River, a tributary of Guaíba Lake, is a major economic and environmental source for Rio Grande do Sul, a state located in the far south of Brazil; METHODS: This study evaluated the interference of sediment from this river in the reproduction and survival of 320 microcrustaceans (80 organisms per site) of the Daphnia magna species. Four sites between the middle course and the river mouth were monitored using eight samples from each site, between June/06 and April/10. Mortality higher than 20% suggested the acute action of the sample on the daphniids, while low reproduction indicated the presence of chronic toxicity. Sometimes an effect on survival was noted, but the number of individuals generated was always low. Semi-static chronic assays (21 day) were developed in 50 mL beakers using sediment and M4 culture medium at a ratio of 1:4 (v:v). Each beakers received a microcrustacean born from lots presenting LC50-24 hours = 0.98 mg K2Cr2O7 ± 0.04 mg totaling ten replicas per sample. The assays were developed under controlled light (16 hours light/day) and temperature (20 ºC ± 2 ºC) conditions; RESULTS: Duncan test showed a variation in reproduction (p < 0.05) with the presence of chronic toxicity. There was less reproductive activity in 91% of the samples, while for survival the reduction attained 9%. Spearman correlation identified the dependence between the rainfall index and reproduction in one of the samples and was absent when the rainfall index was compared to survival; CONCLUSIONS: Taquari River presented episodes of toxicity, and it is necessary to continue studies in the area and to inspect local sources of pollution, as already has been done. Chronic bioassays should be maintained when the purpose is to evaluate environmental quality, since reproduction proved more sensitive than survival.

Assessing Orinoco river sediment discharge trend using MODIS satellite images

2019 ◽  
Vol 91 ◽  
pp. 320-331 ◽  
Author(s):  
Marjorie Gallay ◽  
Jean-Michel Martinez ◽  
Abrahan Mora ◽  
Bartolo Castellano ◽  
Santiago Yépez ◽  
...  
Keyword(s):  
Satellite Images ◽  
River Sediment ◽  
Sediment Discharge ◽  
Orinoco River ◽  
Modis Satellite Images

scholarly journals FIELD STUDY ON SEDIMENT TRANSPORT AROUND RIVER MOUTH OPENING AT THE TENRYU RIVER IN JAPAN

2018 ◽  
pp. 69
Author(s):  
Yuya Sasaki ◽  
Shinji Sato
Keyword(s):  
Sediment Transport ◽  
Coastal Erosion ◽  
Mouth Opening ◽  
River Mouth ◽  
Sediment Supply ◽  
Optimal Management ◽  
Central Japan ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Near Future

The Tenryu River mouth and its surrounding coast, located on the Pacific Ocean side in the central Japan, have been suffered from severe coastal erosion. Although increasing sediment supply from river to coast is planned by sand-bypassing through the upstream dams in near future, a better understanding on morphology change around river mouth is needed to facilitate optimal management of the river mouth. Especially, understanding on sediment transport around the river mouth opening is essential to prevent river mouth closure which leads to many problems. The purpose of this study is to reveal the mechanism of sediment transport around river mouth opening.

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