scholarly journals Response of salinity intrusion to the hydrodynamic conditions and river mouth morphological changes induced by the 2011 tsunami

2020 ◽  
Vol 14 (2) ◽  
pp. 1-16
Author(s):  
Nguyen Xuan Tinh ◽  
Jin Wang ◽  
Hitoshi Tanaka ◽  
Kinuko Ito
Keyword(s):  
Morphological Changes ◽  
Salt Water ◽  
Water Discharge ◽  
River Mouth ◽  
River Channel ◽  
Salt Transport ◽  
Ground Subsidence ◽  
Fishing Ground ◽  
Estuarine System ◽  
Salinity Intrusion

The 2011 Tohoku Earthquake and tsunami were one of the most devastating natural disasters in history. It caused significant ground subsidence and erosion along the Japan coastline. The Natori river mouth which is a habitat for both fishes and bivalves, as an important fishing ground, has been damaged by the tsunami because of the change of the process of salt transport in an estuarine system. In general, salinity intrusion into the river mouth can be affected by many factors such as river water discharge and tidal level, as well as estuarine morphology. In this study, the response of salinity intrusion to the river mouth morphological changes induced by the 2011 Tsunami is investigated. The topographical changes caused by the tsunami are mainly divided into two stages. The first is the direct action of the tsunami, which caused the severe scouring of the coast and the widening of the river. The results have clearly indicated that after tsunami the salt water can intrude much further upstream compare to the condition before the tsunami event. Another changes occurred during the restoration process after the tsunami. The sediment accumulation in the river channel prevented the salt water from entering the river channel, which reduced the salt intrusion degree. However, the effect of the morphology change caused directly by the tsunami is far greater than the sedimentation of the river. Keywords: salinity intrusion; river morphology; tsunami impact; numerical simulation; EFDC model.

Prediction of salinity intrusion in Danshuei estuarine system

2008 ◽  
Vol 39 (5-6) ◽  
pp. 497-505 ◽  
Author(s):  
A. Etemad-Shahidi ◽  
A. Dorostkar ◽  
Wen-Cheng Liu
Keyword(s):  
Fresh Water ◽  
Water Discharge ◽  
Eddy Diffusivity ◽  
Turbulence Closure ◽  
Estuarine System ◽  
Salinity Intrusion ◽  
Closure Scheme ◽  
Fresh Water Discharge ◽  
Vertical Eddy Diffusivity ◽  
Vertical Eddy

The main parameters that affect the flow conditions and intrusion of salt water in an estuary system are tides and the seasonal variation of water discharge. A laterally averaged two-dimensional numerical model called MIKE 11 XZ is used to simulate the hydrodynamics and salinity intrusion of Danshuei River estuarine system. This model can simulate hydrodynamics and water quality in estuaries, reservoirs and lakes. MIKE 11 XZ solves the Reynolds-averaged Navier–Stokes equations by using Abbott–Ionescu finite difference scheme in a non-dimensional vertical σ-coordinate. Vertical eddy diffusivity in the model can be determined by a constant value, a mixing length theory and a k or k−ɛ turbulence closure scheme with Richardson number correction. A series of comprehensive field data obtained from Danshuei estuarine system is used for evaluation, calibration and verification of the model. The friction coefficient was calibrated and verified using water surface elevation and velocity measurements, respectively. Then the vertical eddy diffusivity was calibrated and verified through comparison of salinity measurements in different layers of several stations. Reasonable agreement was obtained between the model results and the observed data using k−ɛ turbulence closure scheme. The model application was investigated with different discharges and the effect of discharge variation on salinity intrusion was determined. The results showed that the fresh water discharge is the main parameter that affects the salinity intrusion in this system. Finally, simple power equations are suggested to predict the salinity intrusion due to the fresh water discharge in different tributaries of the system.

Seasonal movement and size distribution of three commercially important Australian prawn species (Crustacea : Penaeidae) within an estuarine system

1983 ◽  
Vol 34 (5) ◽  
pp. 727 ◽  
Author(s):  
RG Coles ◽  
JG Greenwood
Keyword(s):  
Life Histories ◽  
Salt Water ◽  
River Mouth ◽  
Distribution Patterns ◽  
Estuarine System ◽  
Rainfall Runoff ◽  
Seasonal Movement ◽  
Southern Half ◽  
Commercially Important ◽  
Abiotic Stimuli

Three penaeid prawn species, Penaeus plebejus Hesse, Metapenaeus bennettae Racek & Dall, and M. macleayi (Haswell), were sampled using a beam trawl, at four sites for 16 months in the Noosa River, Queensland, and data collected are used to provide generalized life histories for the three species and to discuss the composition and timing of the commercial bait prawn fishery. P. plebejus individuals were recruited to the river throughout the year, M. bennettae between March and June, and M. macleayi between April and July. P. plebejus juveniles remained only briefly in the river and were most numerous at sites near the river mouth. There was no distinct period of migration of this species from the river. M. bennettae and M. macleayi individuals remained in the river until December and March, respectively, when, in the absence of obvious abiotic stimuli such as rainfall runoff and reduced salinities, there was a marked egress from the river. While in the river, both of these species could be caught through the zone of salt-water penetration up to 35 km from the sea, and both were most numerous in the southern half of Lake Cootharaba in a zone of approximately 19 × 10-3 mean salinity. Similarity between these and other distribution patterns recorded in topographically different rivers suggests salinity is an important determining factor in the distribution of these prawns.

scholarly journals Linkages Between Sinuosity Index and Flood Sustainability: A Study of Morna River (Maharashtra), India

2021 ◽  
Vol 16 (2) ◽  
pp. 649-661
Author(s):  
Nilesh K. Susware ◽  
Jagdish B. Sapkale ◽  
Vinaya N. Susware ◽  
Shubham K. Gavhane
Keyword(s):  
Agricultural Land ◽  
Morphological Changes ◽  
Water Discharge ◽  
Research Work ◽  
Flood Management ◽  
River Channel ◽  
Flood Events ◽  
Sinuosity Index ◽  
Channel Changes ◽  
Stability And Instability

The morphological changes in the river channel over periods that occur due to the flood events, affected the sinuosity index of the river channel. The river characteristic like sinuosity also determines the intensity of flood in a channel. Recent flood losses have increased as a result of variability in rainfall; simultaneously such problems are coming up with sustainable development. The attempted research study has been carried out to evaluate and understand the river channel changes and bank stability of the Morna river in Maharashtra. The research work also identified the pattern/planform of the river. Morna river meets Warna river near the Mangle village. Most of the streams in the upper basin area are non-perennial. The occurrence of floods takes place due to seasonal rainfall. An index of Sinuosity was used to analyze variation in river courses, as well as identify stability and instability. Therefore, this may facilitate predicting probable riverbank erosion sites and also support sustainable flood management planning for these sites during forthcoming flood events. The sinuosity index of the Morna river ranges from 1.09 to 1.44. The sinuosity indexes for the Morna river and tributaries of its sub-basins/watersheds have been calculated using geospatial techniques. The disparities in sinuosity indexes of the Morna basin and sub-watersheds having a good correlation with slope of the river , fluvial processes, water discharge and hydraulic aspects of the river channel. Seasonal potential flood risk for the agricultural land may be found at the confluence of the Warna river and its tributary Morna river when it receives heavy rainfall in upstream.

scholarly journals HYDROCHEMICAL STUDIES OF THE PARTIZANSKAYA RIVER ESTUARY (NAKHODKA BAY, JAPAN SEA) IN SUMMER SEASON OF LOW WATER DISCHARGE

2018 ◽  
Vol 193 ◽  
pp. 143-152 ◽  
Author(s):  
P. Yu. Semkin ◽  
P. A. Tishchenko ◽  
T. A. Mikhailik ◽  
Yu. A. Barabanshchikov ◽  
G. Yu. Pavlova ◽  
...  
Keyword(s):  
River Water ◽  
Salt Water ◽  
Water Discharge ◽  
Chlorophyll Concentration ◽  
River Estuary ◽  
River Mouth ◽  
Japan Sea ◽  
Bottom Layer ◽  
Autochthonous Organic Matter ◽  
Limited Water Exchange

Chemical water parameters in the Partizanskaya River estuary were measured on July 18–19, 2012 in conditions of low water discharge (20.1 m3 /s). In these conditions, the cline of salt water at the bottom penetrated up to 11 km upstream from the river mouth and the fresh river water passed the estuarine zone of mixing in approximately 2 days. Salt composition of the mixed water in the estuary had conservative dependence on salinity. By dynamical signs, the estuary could be divided into two zones: i) zone of active exchange between the surface freshwater layer and the bottom salted layer on the distance 5.5 km from the river mouth to the first sandy riverbank that the fresh river water passed in 12 hours, and ii) the upper part of the estuary with limited water exchange. The complex of water environments in the estuary, as good water transparency, strong stratification, and high concentrations of terrestrial nutrients, was favorable for phytoplankton blooming, so the chlorophyll concentration in the estuarine waters exceeded 40 μg/L. Destruction of autochthonous organic matter caused anomalies in distribution of carbonate and nutrient parameters and was accompanied by hypoxia in the bottom layer with the dissolved oxygen content lowering to 61 μM/kg.

scholarly journals EFFECT OF MORPHOLOGICAL CHANGES AND WAVES ON SALINITY INTRUSION IN THE NANAKITA RIVER MOUTH

2006 ◽  
Vol 50 ◽  
pp. 139-144 ◽  
Author(s):  
Nguyen Trung VIET ◽  
Hitoshi TANAKA ◽  
Daisuke NAKAYAMA ◽  
Hiroto YAMAJI
Keyword(s):  
Morphological Changes ◽  
River Mouth ◽  
Salinity Intrusion

scholarly journals Implications of an extensive salt water barrage on the distribution of black clam in a tropical estuarine system, Southwest coast of India

Oceanologia ◽  
2021 ◽  
Author(s):  
Arunpandi Nagarathinam ◽  
Jyothibabu Retnamma ◽  
Jagadeesan Loganathan ◽  
Parthasarathi Singaram ◽  
Savitha Mohanan ◽  
...  
Keyword(s):  
Salt Water ◽  
Estuarine System ◽  
Southwest Coast Of India ◽  
Southwest Coast ◽  
Tropical Estuarine

scholarly journals Nutrient behavior in a highly-eutrophicated tropical estuarine system

2016 ◽  
Vol 28 (0) ◽  
Author(s):  
Nilva Brandini ◽  
◽  
Ana Paula de Castro Rodrigues ◽  
Ilene Matanó Abreu ◽  
Luiz Carlos Cotovicz Junior ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chlorophyll A ◽  
River Mouth ◽  
Nutrient Concentrations ◽  
Phytoplankton Production ◽  
Small Scale ◽  
Estuarine System ◽  
Temperature Conductivity ◽  
Se Brazil ◽  
Iguaçu River

Abstract Aim: There are few studies dealing with the biogeochemical processes occurring in small estuaries receiving high sewage loading in tropical regions. The aim of this investigation was to characterize the biogeochemical behavior of nutrients in superficial waters collected at the Iguaçu estuarine system, during specific conditions (neap tide), located at the inner sector of a heavily eutrophicated embayment (Guanabara Bay, SE Brazil). Methods Physical and chemical variables were measured in situ (pH, temperature, conductivity, salinity, total dissolved solids, transparency, dissolved oxygen), whereas suspended particulate matter, chlorophyll a, phaepigments and nutrients (carbon, nitrogen and phosphorus forms) were measured in laboratory across the mesohaline estuarine gradient. Results The Iguaçu River mouth is in a high stage of eutrophication, considering nutrient concentrations, chlorophyll a and transparency of water column. Results indicate a transition from heterotrophic conditions to autotrophic conditions, since the nutrients concentrations showed a decreasing pattern along the saline gradient, while the chlorophyll an increased over the transects. The pH values and chlorophyll : phaeopigments ratios are significantly related to the amount and quality of organic matter contents, especially at transects under strong marine influence. More than 95% of the dissolved and total nitrogen concentrations are represented by NH4+ contributions, which are related to the ammonification of organic matter contents in this region, indicating the existence of untreated sewage loads in this area. Conclusion In this study, the Iguaçu River seemed to contribute with high inputs of nutrients that support important phytoplankton production at the inner regions of the bay related to the CO2 sink and autotrophic metabolism, showing the importance of verifying the biogeochemical behaviors of nutrients in estuarine areas, even in small scale.

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