Mathematical Modeling of the Suspended Sediment Dynamics in the Riverbeds and Valleys of Lithuanian Rivers and Their Deltas

Rimkus, Alfonsas; Vaikasas, Saulius

doi:10.5772/31203

Cited by 2 publications

(2 citation statements)

References 22 publications

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“…The reduction of sediment concentration is more intensive in the wider strips of the valley (Vaikasas, 2009). In the flooded valleys the flow velocity is lower, when the water flows along the valley, the flow velocity declines in the riverbed too (Rimkus, Vaikasas, 2012). Soil agrochemical properties depended on the flood flow intensity.…”

Section: Resultsmentioning

confidence: 99%

The fluctuation of calcium and magnesium concentrations in the floodwater in the Nemunas and Minija lowlands

Katutis

Rudzianskaitė

2015

Zemdirbyste-Agriculture

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Calcium (Ca) and magnesium (Mg) are vital elements for the neutralization of soil or water acidity, which is associated with the activity of biota, mobility of heavy metals, phosphorus and other important elements. The current research was aimed to estimate the trends in the fluctuation of calcium and magnesium ions in the floodwater using traditional experimental methods. The studies were carried out during the 1987-2010 period in the Nemunas lowland (upper (Rambynas-Plaškiai) and lower (Girininkai-Smalkai) zones) and in the Minija lowland. In the floodwater of both rivers, the concentration of Ca 2+ was up to three times as high as the mean annual concentration in the river and that of Mg 2+ concentration by up to 1.6 times higher than in the river. A trend towards increasing of these ions concentration in the floodwater was established. In the upper zone of the Nemunas lowland the concentrations of Ca 2+ (159-248 mg l -1 ) and Mg 2+ (14.3-29.3 mg l -1 ) in floodwater were something higher than those in the lower zone -152-240 and 13.5-25.3 mg l -1 , respectively. These differences were significant: Ca 2+ -t act. = 1.75 > t 0.05 = 1.65 and Mg 2+ -t act. = 3.25 > t 0.05 = 1.65. The concentration of these ions with increasing distance from the riverbed decreased and was the lowest in the pre-land part of the floodplain. The strongest correlation between Ca 2+ (r 2 = 0.82, t act. = 7.87 > t 0.05 = 1.75) and Mg 2+ (r 2 = 0.43, t act. = 3.25 > t 0.05 = 1.75) concentrations in the water and soil was determined in the lowest parts of the relief (<0 m), when the floodwater was at more than 1 km distance from the riverbed. The concentrations of the tested ions at the beginning of flood reflect the amount of substances carried from the catchment areas into the rivers. The quality of the water flowing through the valley depended on the relief height, flow velocities and distribution and soil properties.

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Section: Resultsmentioning

confidence: 99%

The fluctuation of calcium and magnesium concentrations in the floodwater in the Nemunas and Minija lowlands

Katutis

Rudzianskaitė

2015

Zemdirbyste-Agriculture

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“…With respect to the specific features of the Nemunas River, the lower SSC for the high river discharges can cause only minor uncertainties for the model results. Firstly, during the floods, especially large ones, in the delta region, the flow velocities hardly decreases because of the water overflow to the valley [68]. Secondly, it is known that during a flood, big amounts of sediments (about 35% of the suspended sediment input) are deposited in the delta meadows, due to favorable conditions for deposition, and do not reach the Curonian Lagoon [69].…”

Section: In Situ Data and Sediment Rating Curvementioning

confidence: 99%

Sediment Transport Mechanisms in a Lagoon with High River Discharge and Sediment Loading

Mėžinė

Ferrarin

Vaičiūtė

et al. 2019

Water

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The aim of this study was to investigate the sediment dynamics in the largest lagoon in Europe (Curonian Lagoon, Lithuania) through the analysis of in situ data and the application of a sediment transport model. This approach allowed to identify the propagation pathway of the riverine suspended sediments, to map erosion-accumulation zones in the lagoon and calculate the sediment budget over a 13-year-long simulation. Sampled suspended sediment concentration data are important for understanding the characteristics of the riverine and lagoon sediments, and show that the suspended organic matter plays a crucial role on the sediment dynamics for this coastal system. The numerical experiments carried out to study sediment dynamics gave satisfactory results and the possibility to get a holistic view of the system. The applied sediment transport model with a new formula for settling velocity was used to estimate the patterns of the suspended sediments and the seasonal and spatial sediment distribution in the whole river–lagoon–sea system. The numerical model also allowed understanding the sensitivity of the system to strong wind events and the presence of ice. The results reveal that during extreme storm events, more than 11.4 × 106 kg of sediments are washed out of the system. Scenarios without ice cover indicate that the lagoon would have much higher suspended sediment concentrations in the winter season comparing with the present situation with ice. The results of an analysis of a long-term (13 years) simulation demonstrate that on average, 62% of the riverine sediments are trapped inside the lagoon, with a marked spatially varying distribution of accumulation zones.

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Mathematical Modeling of the Suspended Sediment Dynamics in the Riverbeds and Valleys of Lithuanian Rivers and Their Deltas

Cited by 2 publications

References 22 publications

The fluctuation of calcium and magnesium concentrations in the floodwater in the Nemunas and Minija lowlands

The fluctuation of calcium and magnesium concentrations in the floodwater in the Nemunas and Minija lowlands

Sediment Transport Mechanisms in a Lagoon with High River Discharge and Sediment Loading

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