Development and Application of 2-D Depth-Averaged Mobile Bed Model with Bank Erosion Mechanism

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Study on Local Scour around Bridge Pier Due to the Dam Removal

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

Erosion Control Plans for JiJi Weir Downstream Channel

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

Modeling River Morphodynamic Process Using a Depth-Averaged Computational Model and an Application to a Mountain River

Bank erosion is a dominant river morphodynamic process resulting in encroaching valuable farming land and channel migration. Prediction of bank erosion and channel migration requires understanding of the morphodynamics of the entire river system. Numerical modeling is an ideal method for this task. However, models with full capabilities and applications on complex real-world problems are rare. In this study the finite element-based computational model, CCHE2D, and its flow, sediment transport, and bank erosion modules are introduced. The model is capable of simulating unsteady flows with nonuniform sediment transport and cohesive/non-cohesive material bank erosion. The effects of helical secondary current on sediment transport induced by flow curvatures are reflected in both bed load and suspended sediment formulations. This model is validated using multiple sets of experimental data and applied to bank erosion problems of the Chuoshui River, a real-world mountain river in Taiwan. Characterized by typhoon floods, steep channel slopes, and high sediment load and mobility, this river often exhibits a braided pattern consisting of multiple curved channels. Channel bed change and bank erosion caused by 10 years of typhoon floods in a selected reach have been simulated, and the computed bank erosion results agreed with the field observation

Improving the 2d numerical simulations on local scour hole around spur dikes

Local scour is a common threat to structures such as bridge piers, abutments, and dikes that are constructed on natural rivers. To reduce the risk of foundation failure, the understanding of local scour phenomenon around hydraulic structures is important. The well-predicted scour depth can be used as a reference for structural foundation design and river management. Numerical simulation is relatively efficient at studying these issues. Currently, two-dimensional (2D) mobile-bed models are widely used for river engineering. However, a common 2D model is inadequate for solving the three-dimensional (3D) flow field and local scour phenomenon because of the depth-averaged hypothesis. This causes the predicted scour depth to often be underestimated. In this study, a repose angle formula and bed geometry adjustment mechanism are integrated into a 2D mobile-bed model to improve the numerical simulation of local scour holes around structures. Comparison of the calculated and measured bed variation data reveals that a numerical model involving the improvement technique can predict the geometry of a local scour hole around spur dikes with reasonable accuracy and reliability

Modeling the Combined Effects of River Stage and Groundwater Flow on Riverbank Stability Before and After Dam Removal

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

Assessment of Dam Removal in Dajia River Basin with Numerical Modeling

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

Study on River Migration and Stable Water Supply Countermeasure in the Reach of Kaoping Weir

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Erosion Control at Downstream of Reservoir Using In-stream Weirs

As low-head hydraulic structures, instream weirs are built across rivers to control the upstream water surface elevation and the downstream flow conditions. This chapter presents a study of erosion control using instream weirs at downstream of a reservoir; JiJi Weir was built across the longest river in Taiwan, Chuoshui Creek, a mountainous river with steep slopes. Due to the easy-to-be-eroded fine lithology layers of mud, shiver, and sandstones on channel bed, the downstream of JiJi Weir had suffered from severe channel incision and head-cut development problems, which greatly threatens the integrity of the dam. To protect the JiJi Weir and its downstream channel from serious channel erosions, the Water Resources Agency (WRA) of Taiwan proposed erosion control plans that multiple instream weir structures were to be installed along the downstream channel of JiJi Weir. A three-dimensional (3D) numerical model, CCHE3D model with capabilities of simulating bedrock erosions, was used to evaluate those erosion control plans and thus explore for the optimal design