Numerical meander models

Numerical meander models

Type

Hydromorphological models

Basic principles

Linearized fundamental equations for conservation of water mass and water flow momentum, spatially averaged over water depth and time-averaged over all turbulent fluctuations. Linearized parameterized relation for effect of helical flow on bed shear stress direction. Empirical bank migration predictor. Possibly linearized equilibrium sediment transport predictor. Possibly linearized empirical relation for effect of sloping beds on sediment transport magnitude and direction. Linearized Exner equation for conservation of sediment mass.

Outputs

Flow velocities, water depths, water levels, flow shear stresses. Sediment transport, bed level, bank erosion, meander migration.

Rivertypes

• Segment
•    Segment

Related Pressures

• Hydropeaking
• Sediment discharge from dredging
• Reservoir flushing
• Hydrological regime modification
• Interbasin flow transfers
• Discharge diversions and returns
• Alteration of instream habitat
• Sand and gravel extraction
• Sedimentation and sediment input
• Embankments, levees or dikes
• Loss of vertical connectivity
• Impoundment
• Alteration of riparian vegetation
• Channelisation / cross section alteration

Related Measures

• Improve/Create water storage
• Reduce water consumption
• Increase minimum flows
• Recycle used water
• Improve water retention
• Reduce surface water abstraction with return
• Water diversion and transfer
• Reduce surface water abstraction without return
• Reduce groundwater extraction
• Reduce anthropogenic flow peaks
• Modify hydropeaking
• Shorten the length of impounded reaches
• Increase flood frequency and duration in riparian zones or floodplains
• Favour morphogenic flows
• Link flood reduction with ecological restoration
• Ensure minimum flows
• Manage aquatic vegetation
• Establish environmental flows / naturalise flow regimes
• Create low flow channels in over-sized channels
• Narrow water courses
• Widen water courses
• Allow/increase lateral channel migration or river mobility
• Remeander water courses
• Shallow water courses
• Develop riparian forest
• Remove non-native substratum
• Adjust land use to develop riparian vegetation
• Revegetate riparian zones
• Remove bank fixation
• Adjust land use to reduce nutrient, sediment input or shore erosion

Useful references

Selected software systems

MIANDRAS

Theoretical background

Crosato A. (1989): Meander migration prediction. Excerpta, GNI, Vol.4, Libreria Progetto, Padova, pp.169-198.

Crosato: A. (2008): Analysis and modelling of river meandering. PhD thesis, Delft University of Technology, IOS Press, ISBN 978-1-58603-915-8.

Ikeda S., Parker G., Sawai K. (1981): Bend theory of river meanders, Part 1, Linear development. J. Fluid Mech., vol.112, pp.363-377. http://dx.doi.org/10.1017/S0022112081000451