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Surface water–ground Water Interactions and Modeling Applications
Published in Calvin C. Chien, Miguel A. Medina, George F. Pinder, Danny D. Reible, Brent E. Sleep, Chunmiao Zheng, and Sediment, 2003
Calvin C. Chien, Miguel A. Medina, George F. Pinder, Danny D. Reible, Brent E. Sleep, Chunmiao Zheng
The same sort of flow pattern also can develop at smaller spatial scales. Geomorphic evolution of stream channels produces a wide range of periodic topographical features. High-gradient streams are often characterized by pool-riffle sequences, which can produce stream–subsurface exchange flows similar to those envisioned by Hynes (Harvey and Bencala, 1993; Wondzell and Swanson, 1996). Lower-gradient, alluvial rivers generally have large planform meanders which can generally be expected to admit a stream–subsurface exchange flow. These meanders are subject to a difference in hydraulic head from the upstream to the downstream side, which yields an exchange flow through the meander (Harvey and Bencala, 1993; Wroblicky et al., 1998). Additional stream–subsurface exchange can be induced whenever the stream changes orientation relative to the local ground water flow system. These flows can be influenced by some particular features of the local ground water flow system such as preferential subsurface flows through relict stream channels (Wondzell and Swanson, 1996).
Numerical modelling of the Danube river channel morphological development at the Slovak–Hungarian river section
Published in Silke Wieprecht, Stefan Haun, Karolin Weber, Markus Noack, Kristina Terheiden, River Sedimentation, 2016
Based on cross-section averaged variables, 1D numerical modelling of alluvial rivers has been most widely used in the fields of river training, hydropower generation, flood control and disaster alleviation, water supply, navigation improvement, as well as environment enhancement. It has been recognised that 1D models are appropriate primarily for long-term and long-reach situations (Cao & Carling 2002). There are several limitations connected with the application of 1D morphological models. In the cases of large rivers, 1D modelling can provide evaluation of longterm channel changes and delivery of sediments at a regional scale, or provide boundary condition input for multi-dimensional modelling (Heath & Sharp 2010).
Process-based approach on tidal inlet evolution – Part 1
Published in C. Marjolein Dohmen-Janssen, Suzanne J.M.H. Hulscher, River, Coastal and Estuarine Morphodynamics: RCEM 2007, 2019
D.M.P.K. Dissanayake, J.A. Roelvink
Alluvial rivers are characterized by strong interactions between bed morphology adaptations, sediment transport and flow structure. The different interactions are schematised in figure 1 and can be described as follows: the sediment transport is controlled by the flow structure whereas the flow structure depends on the bed geometry that is itself influenced by the sediment transport. The central element of these interactions is the buoyancy-affected turbulence. On one hand, the turbulent motions induce lift effect on the particles and counteract the gravitational force responsible for the particle settling. On the other hand, the presence of the sediment either increases or reduces the turbulent level (Toorman 2003).
Channel migration characteristics of the Yamuna River from 1954 to 2015 in the vicinity of Agra, India: A case study using remote sensing and GIS
Published in International Journal of River Basin Management, 2019
P. Yunus Ali, Dou Jie, Armugha Khan, N. Sravanthi, Liaqat A. K. Rao, Chen Hao
River networks are found to be permanent features of a landscape. Literally, many large rivers define political boundaries that have been in place for centuries. However, river networks are not as stagnant as they may appear and have collected both geologic and geographic evidence that suggests many rivers have been revamped, shifting and moving across a topography over millions of years. Channel-Planform changes, such as river migration, bank erosion, downcutting, and sediment deposition, are typical for an alluvial river (Kummu et al. 2008). Activities such as sand mining, industrial development, and constructions on the riverbank, building dams, and land use changes have altered the natural flow of the rivers (Li et al. 2007, Kummu et al. 2008). Channel-planform changes and its dynamics over time have long been a significant focus of attention in geomorphology (Takagi et al. 2007). The geomorphological processes active in a fluvial system are mainly downcutting and bank accretion, which at the reach scale are seen as the lateral movement of the channel across the floodplain. This lateral movement includes migration, avulsion, meander cutoffs, point bars, braided streams, and channel switching (O’Connor et al. 2003, Beechie et al. 2006). With each process, the river erodes the banks or accrete sediment each year resulting in a gradual rise in elevation of river bed (Hughes 1997, Beechie et al. 2006).
A numerical model for sediment transport and bed change with river ice
Published in Journal of Hydraulic Research, 2018
Sediment transport and bed change is an important consideration in alluvial rivers. The river bathymetry is constantly adjusting to changes in flow conditions, as well as the presence of ice in cold regions. Turcotte, Morse, Bergeron, and Roy (2011) and Ettema (2006) provided reviews on responses of sediment transport and channel morphology to various river ice processes. Most of these responses are not well documented due to difficult field conditions. Quantitative data for further analysis is generally unavailable as a result. Numerical models can provide tools for gaining insights to these processes and help to plan effective field studies. A few numerical model studies exist on sediment transport and bed changes under the influence of river ice covers (Carr & Tuthill, 2012; Kolerski & Shen, 2015; Yang, Zhang, & Shen, 1993). However, no numerical model has been developed that couples river ice dynamics with sediment transport and bed change. This paper presents the development of a sediment transport and bed change model that was coupled with a hydro-thermal-ice dynamics model. The model uses recently developed sediment transport and bed resistance equations for ice-covered conditions (Knack & Shen, 2015). The model is validated using laboratory experiments for open water conditions. Since laboratory or quantitative field observations on bed changes under ice conditions are not available, similar validations could not be made. Key processes on surface ice effects on sediment transport and bed changes in alluvial channels are demonstrated and discussed.
Predicting the geometry of regime rivers using M5 model tree, multivariate adaptive regression splines and least square support vector regression methods
Published in International Journal of River Basin Management, 2019
Saba Shaghaghi, Hossein Bonakdari, Azadeh Gholami, Ozgur Kisi, Andrew Binns, Bahram Gharabaghi
Alluvial rivers tend to naturally form their geometry in order to carry the water and sediment load with no net erosion and sedimentation and to preserve their dimensions with no change (Huang and Nanson 2000, Huang and Foo 2002, Huang et al. 2002). The state of a river in which the amounts of erosion and deposition are in equilibrium and the average dimensions of width, depth and mean bed level (slope) are preserved over time, is expressed as the regime (or stable) condition or dynamic equilibrium (Diplas 1990, Ackert 2000).