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I am simulating a river using Telemac2D.
If the upstream boundary uses flow boundary (Q), and a cross-section is added near the upstream boundary, the cross-section discharge will be basically consistent with the inflow(Q)

However, if I use water source as the upstream discharge (near but not on the boundary), it will be found that the cross-section dischargeis greater than the water source discharge. the larger the discharge, the greater the difference between the two. For example, if the water source discharge is 30m3/s, the cross section flow might be 40m3/s. Why?

both type of source 1, and 2 have this problem.

where does the extra water come from?

I am using v8p5, and the latest version.

The cross-sectional flow rate is 1.3 times that of the water source.

I am using WGS (degree), not Cartesian coordinate system.

Hello,

Can you upload you steering file please?
Do you use WATER DISCHARGE OF SOURCES with or without VELOCITIES OF THE SOURCES ALONG X + VELOCITIES OF THE SOURCES ALONG Y?

If you do not use keywords with names velocities, that means the direction of the flowrate is not prescribed and some water could start to flow opposite to the direction of your section then flows through the section.

This may explain what you see,

Chi-Tuan

Thank you.

I finally found that I should add
COMPATIBLE COMPUTATION OF FLUXES = 1

Good news.
I am not a specialist of control sections feature.

Chi-Tuan