Reservoir sedimentation model

[Anonymous]

hi,

I have been working on a Reservoir sedimentation model. the reservoir top water level is at 2390mAD with drawdown to 2385.5mAD necessary daily for power production. the volume in between acting as live storage. the model is run for 100 years to model sediment build up in the reservoir. everything works as it should, with sediment building up in the upstream end of the reservoir. the results show that upstream, a large proportion of the live storage area is taken up by sediment after 100 years. the model is pretty basic with 100 river sections, extended over the reservoir area and a dam with sluice gates used to model the drawdown etc. Firstly, i need to know the volume of the live storage, and secondly, the volume of live storage used up by the sediment. from the output data/plots etc that i’ve looked though, i cant figure out how to determine these values. would you have any suggestions?

[Chris G.]

To get the live reservoir storage, you’ll have to set up a spreadsheet. Make a RAS table that includes the cum. volume for a wide range of steady flow profiles (so that you have a wide range of reservoir elevations). Then copy and paste those results to a spreadsheet. There you can remove cross sections that are not part of the reservoir, and volumes that are not part of the live storage.

To get sediment that has accumulated in the reservoir, go to the sediment spatial plot and view the mass bed change (tons) for the final output sediment profile.

Check out this post to learn more about the different sediment output variables:

http://hecrasmodel.blogspot.com/2009/03/sediment-output-variables-what-do-they.html

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