Let us consider I have a small dam on which I would like to perform and analysis of siltation and model its dynamics.
What could be some appropriate models for that ? Depending on the model to be used, what kind of data do I need to gather ? If they are historical data, what should be, ideally, on a rough estimate, the appropriate timespan ?
I believe the question is very broad (and possibly not very well stated), but I am mostly interested in the approach. In case one has already performed a siltation modelling case, some links and ideas would be very much appreciated. Thanks.
I feel this is very good example of bed level variation due to afflux , i.e. aggradation.
You need to solve the basic equation for flowing fluid in open channel, i.e. Saint Venants equation , along with sediment continuity equation.
Broadly, if we talk, we should have surveyed cross sections (original) for proposed reservoir, upstream and downstream boundry conditiobs for water and sediment discharge and properties of bed material including a robust sediment transport formula for inclusion in numerical model!!!
Roehl (about 1964) did his study of sediment delivery ratio using dams of various sizes. I am not in the computer that has his studies, but believe available on internet concerning the subject of sediment delivery ratio for several various landtypes in US. If you have the topography of the area before it was a dam and can define the extent of the siltation (bathymetric or sonar or other depth measures to sediment), and its density, etc. you can estimate the amount since dam was installed. Most dams are located in a natural restriction in topography, so there should have been already a valley surface deposit when the dam was installed. If you can find some of the original dam studies, elevation measurements, perhaps those may help you address existing conditions. Large dams are probably going to have more sediment deposited in its headwaters (lake arms, as coarse sediments quickly settle when the velocity falls off. If you have periods of drought, if the exposed bottom firms up enough, you may be able to go in an core to the depths of the sediment and get some good samples on sediment density as it may vary somewhat do to distance from the source tributary.
Sundborg developed a model which was used in this study
Article Measurement and quantification of a sedimentation budget for...
I feel this is very good example of bed level variation due to afflux , i.e. aggradation.
You need to solve the basic equation for flowing fluid in open channel, i.e. Saint Venants equation , along with sediment continuity equation.
Broadly, if we talk, we should have surveyed cross sections (original) for proposed reservoir, upstream and downstream boundry conditiobs for water and sediment discharge and properties of bed material including a robust sediment transport formula for inclusion in numerical model!!!
GSTARS model is a free typical one for dam sedimentation. It is 1D model, assuming flow as set of stream tubes in cross-section. Stream tubes allow to see bed changes in any cross-section. As you talk about small dam, I would think flow is mostly oriented toward the dam, then 1D modelling may be enough.
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