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Published in Quoc VO Thanh, Modeling of Hydrodynamics and Sediment Transport in the Mekong Delta, 2021
Sediment transport in the Mekong River has been estimated by in-situ measurements, sediment rating curve methods; and numerical modeling. Sediment measurements in the Mekong started in the 1960s, inspired by US practices (Walling, 2009). When using data-based methods, the reliability of sediment transport depends on the number of measuring stations, the length of record and temporal resolution of the data. It has been hardly possible to cover a large area like the Mekong Delta with measurements. In addition, discontinuous records and low sampling frequency lead to high uncertainties in sediment budget estimations. A numerical model, calibrated by in-situ measurements and rating curves, is a suitable tool to investigate hydrodynamics and sediment transport in the Mekong Delta in more detail.
An estuary out of equilibrium: The importance of dredging in determining the net sediment flux in the Rhine-Meuse Estuary
Published in Wim Uijttewaal, Mário J. Franca, Daniel Valero, Victor Chavarrias, Clàudia Ylla Arbós, Ralph Schielen, Alessandra Crosato, River Flow 2020, 2020
J.R. Cox, M.G. Kleinhans, Y. Huismans
The Rhine-Meuse Estuary (RME) located in the west of the Netherlands is an estuary that has undergone several anthropogenic changes which have drastically altered the natural morphology and hydrodynamics of the estuary. This is clearly reflected in the changing sediment budget of the estuary. Sediment budgets are a tool frequently applied to coastal and fluvial systems, particularly estuaries and deltas to gain understanding about the complex sediment dynamics and sediment transport patterns occurring in a given study area (Zhang 2015, Dunn 2017). A sediment budget quantifies the net gain or net loss of sediment from an area during a defined time period, typically one year. Previous sediment budgets for the RME indicate that since the 1980s the area has suffered a net loss of sediment (van Dreumel 1995, Snippen et al. 2005, Becker 2015, Frings et al. 2019).A lack of sediment in an estuary leads to a myriad of problems including extreme channel deepening, a loss of ecologically rich areas and increased flooding. Climate change will further change the sediment dynamics in the area, and exacerbate several of these problems. Here, we update and improve the sediment budget estimates for the RME by creating a sediment budget for 2000-2018 using a multi-method approach at two scales: the entire estuary scale (Estuary Budget or EB) and the individual branch scale budget (Branch Budget or BB).
A 2D process-Based model for suspended sediment dynamics: A first step towards ecological modeling
Published in Fernanda Minikowski Achete, Multiple Scales of Suspended Sediment Dynamics in a Complex Geometry Estuary, 2020
Typical SSC in the Delta ranges from 10 to 50 mg L−1, except during high river discharge when SSC can exceed 200 mg L−1 reaching values over 1000 mg L−1 (McKee et al., 2006; Wright and Schoellhamer, 2005). Sediment budget reflects the balance between storage, inflow and outflow of sediment in a system. Studies based on sediment inflow and outflow estimated that about two-third of the sediment entering the system deposits in the Delta (Schoellhamer et al., 2012; Wright and Schoellhamer, 2005). The remaining third is exported to the Bay, and represents on average 50% of the total Bay sediment supply (McKee et al., 2006); the other half comes from smaller watersheds around the Bay (McKee et al., 2013).
Development of a framework for sand auditing of the Chaliyar River basin, Kerala, India using HEC-HMS and HEC-RAS model coupling
Published in International Journal of River Basin Management, 2023
Abhijith Sathya, Santosh G. Thampi, N. R. Chithra
In the previous paragraphs, an attempt has been made to highlight the adverse environmental impacts of unregulated sand mining and the existing practice in India with regard to grant of permission for mining sand. Rinaldi et al. (2005) suggested a fluvial analysis system for monitoring sand mining, identifying extraction sites, determining extraction rates, and predicting the induced effects after reviewing studies from various countries and performing analysis of sediment mining from five rivers in Italy and Poland. Collins and Dunne (1990) recommended a gravel mining management and monitoring programme which determines and records the rate of replenishment, the nature of the river (whether aggrading or degrading over the years), changes in bed elevation, stability of the banks, analysis of the impacts of gravel mining, quantity of gravel extracted, etc. A periodic review of the mineable quantity in relation to the improved replenishment rates was also performed. A sediment budget analysis can indicate relative rates of sediment supply, transport, and extraction. Computer models of sediment transport can be used to evaluate different alternative management strategies, after being calibrated with data from the river under study (Kondolf, 1994). River Sand Mining Management Guidelines of Malaysia published in 2009 recommended the institutionalization of monitoring plans to provide data on bed profile changes and sediment transport capacity so as to enable the authorities to evaluate the long-term impacts of the mining activities both upstream and downstream of sand extraction sites.
Assessing long-term evolution of the fine sediment budget in the Iffezheim reservoir: temporal upscaling of numerical simulations
Published in International Journal of River Basin Management, 2022
Qing Zhang, Gudrun Hillebrand, Thomas Hoffmann, Reinhard Hinkelmann
Dam constructions interrupt the continuity of sediment transport through river systems, causing sediment to accumulate within the reservoir. Consequently, a wide range of sedimentation-related problems may occur, e.g. loss of reservoir storage capacity, unintended changes of the downstream river morphology due to riverbed degradation. Apart from hydrological and morphological impacts, long-term storage of fine-grained contaminated sediment may also cause serious ecological issues, e.g. for water quality, and concerning options for sediment management after dredging or for flushing operations (Vente et al., 2004). Therefore, it is of importance to understand sediment transport processes and to assess the long-term fine sediment budget, which describes the balance between sediment input, sediment output and internal storage of sediment within the study area (Hillebrand & Frings, 2017).
Morphology recovery of the Abukuma River mouth after the 2011 Tohoku tsunami under the interaction between sand spit and sand terrace
Published in Coastal Engineering Journal, 2021
Nguyen Trong Hiep, Hitoshi Tanaka, Nguyen Xuan Tinh
The sediment budget is the total of sediment losses and gains within a defined area or multiple connecting areas over a given time. In the present study, the river mouth morphology was schematically divided into two units: sand terrace and sand spit (Figure 7(a)). Considering that the present study focuses on the relationship between the sand spit and sand terrace, the bed changes in the deep-water area farther than the confined sand terrace and the adjacent coasts are not considered.