Salt Intrusion Tides And Mixing In Multi Channel Estuaries

Multi-channel estuaries, such as the Mekong Delta in Vietnam and the Scheldt in the Netherlands, have characteristics of both the river and the sea, forming an environment influenced by tidal movements of the sea and freshwater flow of the river. This study discusses a predictive analytical approach for salinity intrusion and discharge estimate in multi-channel estuaries. The new approach agrees with 1-D hydrodynamic models and observations, indicating its applicability in practice. It has successfully developed a new theory and a new equation to quantify tidal pumping due to ebb-flood channel residual circulation and the related salt dispersion.

The book describes an integrated theory that links estuary shape to tidal hydraulics, tidal mixing and salt intrusion. The shape of an alluvial estuary is characterised by exponentially varying width and the absence of bottom slope. This topography is closely related to tidal parameters, hydraulic parameters and parameters that describe 1-dimensional mixing and salt intrusion. Starting from the fundamental equations for conservation of mass and momentum, analytical equations are derived that relate the topography to tidal parameters (tidal excursion, phase lag, tidal damping, tidal amplification), wave celerity, lateral and vertical mixing and salt intrusion. The book presents a review of the state of the art, a comprehensive theoretical background and ample case illustrations from all over the world. It provides tools with which human interference in estuary dynamics can be described and predicted, resulting from, for instance: upstream fresh water abstraction, dredging, climate change or sea-level rise. In describing the interactions between tide, topography, water quality and river discharge, it provides useful information for hydraulic engineers, morphologists, ecologists and people concerned with water quality in alluvial estuaries. Although the book can be used as a text book, it is mainly a monograph aimed at graduate students and researchers. * Provides new integrated theory for tidal hydraulics, tidal mixing and salt intrusion in alluvial estuaries * Presents a consistent set of analytical equations to compute tidal movement, tidal mixing and salt intrusion, derived from the fundamental laws of conservation of mass and momentum * Serves as a practical guide with many illustrations of applications in real estuaries

An experimental and analytical study of the basic factors which determine the instantaneous longitudinal distribution of salinity in a partially mixed estuary of constant section is presented. The mass-transfer equation is solved in two parts: (a) the quasi-steady-state convective-diffusion problem for an observer moving with the tidal velocity, and (b) the cyclic translation of saline water due to the tidal velocity. In the steady-state portion the apparent longitudinal diffusion coefficient is a function of the turbulence induced by the tide and of the internal circulations induced by the density difference. An expression is developed for the intrusion length as a function of the estuary length, mean depth, tidal amplitude and period, fresh-water discharge, ocean salinity, and estuary roughness. A stratification number is defined which expresses the degree of stratification or mixing in an estuary. (Author).

This research aims to investigate the prevailing sediment dynamics and the sediment budget in the Mekong Delta by using a process-based model. Understanding sediment dynamics for the Mekong Delta requires high resolution analysis and detailed data, which is a challenge for managers and scientists. This study introduces such an approach and focuses on modeling the entire system with a process-based approach with Delft3D-4 and Delft3D Flexible Mesh (DFM). The first model is used to explore sediment dynamics at the coastal zone. The latter model allows straightforward coupling of 1D and 2D grids, making it suitable for analyzing the complex river and canal network of the Mekong Delta. The validated model suggests that the Mekong Delta receives ~99 Mt/year sediment from the Mekong River. This is much lower than the common estimate of 160 Mt/year. Only about 23% of the modelled total sediment load at Kratie is exported to the sea. The remaining portion is trapped in the rivers and floodplains of the Mekong Delta. The results advance understanding of sediment dynamics and sediment budget in the Mekong Delta. As such the model is an efficient tool to support delta management and planning.

The Mekong River Basin: Ecohydrological Complexity from Catchment to Coast, Volume Three presents real facts, data and predictions for quantifying human-induced changes throughout the Mekong watershed, including its estuaries and coasts, and proposes solutions to decrease or mitigate the negative effect and enable sustainable development. This is the first work to link socio–ecological interaction study over the whole Mekong River basin through the lens of ecohydrology. Each chapter is written by a leading expert, with coverage on climate change, groundwater, land use, flooding drought, biodiversity and anthropological issues. Human activities are enormous in the whole watershed and are still increasing throughout the catchment, with severe negative impacts on natural resources are emerging. Among these activities, hydropower dams, especially a series of 11 dams in China, are the most critical as they generate massive changes throughout the system, including in the delta and to the livelihoods of millions of people and they threaten sustainability. Presents an extensive collection of eco-hydrological changes in the river basin driven by both nature and anthropological factors Provides state of the art modeling, data analysis methodologies for complex socio-ecological complexity applied in the Mekong river basin Includes specific cases of ecohydrology in the river basin, especially from the Mekong delta

This book comprises selected proceedings of the 5th International Conference on Water Resources 2021 (ICWR2021) focusing on innovations and preparations to face the water-related challenges. Focus is given in the area of quantitative and qualitative water resource analyses comprising of forecasting, modelling and water governance. The contents will be useful to researchers, educators, practitioners and policy-makers alike.