User Forum of Software BASEMENT

moar.diego

User

Registered: 2015-09-22

Posts: 5

Sediment transport: no sediment inflow

Hi,
I'm working on a 2D simulation with Basement v.2.5.3. I have two questions about it:
1) I have set the model output timestep to 1000 s. I need to know which output value is given between two time steps (i.e. depth): a) the maximum value during this period or b) the values at that particular time step.
2) I'm trying to perform the simulation with sediment transport, using the MORPHOLOGY block. I already performed a simulation that worked fine, but now I have modified the upper part of the mesh to consider a longer river reach. But now the software doesn't take in input the sediment hydrograph: in the console I have for every time step Q_sed(in)=0, and also in the boundary_history file. What could be the problem?

Thanks for helping

Matteo Facchini

Developer

From: Trento

Registered: 2014-09-05

Posts: 284

Re: Sediment transport: no sediment inflow

Hi Diego,

1) the answer is b) the values at that particular time step.
2) have you properly set the new upstream points as upstream boundary? By changing the geometry you will have to set again the upstream boundary in the GEOMETRY block under STRINGDEF and then you should refer to that in the MORPHOLOGY block under BEDLOAD/BOUNDARY/string_name

I hope this helps

regards

Matteo

moar.diego

User

Registered: 2015-09-22

Posts: 5

Re: Sediment transport: no sediment inflow

Thanks Matteo.
Yes I have set for the sediment inflow the same points as the water inflow, both at the upper boundary of the mesh. The software starts to read the sediment inflow only after about 3200s. What could the problem?

Last edited by moar.diego (2016-02-26 14:32:33)

moar.diego

User

Registered: 2015-09-22

Posts: 5

Re: Sediment transport: no sediment inflow

It the GUI the Qsed_in is the same of the sediment hydrograph (used as BC) only for the first time steps. After than it becomes always 0.0. Can anyone plesae help me to understand what's the problem? I have tried settinng the same nodes for water inflow and sediment inflow, and also to set for the sediment only a part of these, but the problem persists.

Diego

moar.diego

User

Registered: 2015-09-22

Posts: 5

Re: Sediment transport: no sediment inflow

I noted that running a simulation with the gravitational transport block the software reads correctly the sediment inflow, without that block it works not fine. But now with this block the simulation leads to a lot of sediment deposition in the channel (up to 7 meters high and 15 meters wide) that does not seem reasonable. What could be the problem of such a big deposition? I used the mpm formula (as reccomended), also if the slopes are quite high and it would be better the Smart-Jaeggi formula.

Regards,

Diego