Add support for transient UserDemand return factor

[SouthEndMusic]

@Fati-Mon requested for one of her models that we support transient UserDemand return flow.

This is currently not supported, but it is already possible to put it in the UserDemand \ time table. #1229 is for avoiding confusion about this for time tables in general.

[SnippenE]

from planning session 16-5-2024: check if a flag is implemented in code.

[Fati-Mon]

@Jingru923 how do you define the return flow over time?

I have this now:

# DEMAND (irrigation)
model.user_demand.add(
    Node(6, Point(-1.5, 1.0), name='IrrA'),
    [user_demand.Time(
        demand=[0.0, 0.0, 10, 12, 12, 0.0],
        return_factor=[0.0, 0.0, 0.2, 0.5, 0.5, 0.0],
        min_level=0,
        priority=1,
        time=[starttime, "2022-03-31", "2022-04-01", "2022-07-01", "2022-09-30", "2022-10-01"]
        )
    ]
)

When it irrigates 10 return 20% and when it irrigates 12 return 50%
But return over time remains zero.

[Jingru923]

Hi @Fati-Mon the code looks correct to me. But we will have a look.

[visr]

@Fati-Mon which version are you running with, what is the output of ribasim --version?