Weir dependent "weir dam multiplier"

Len Geisler

I've got a project with a lot of weirs. For 95% of the weirs the weir dam multiplier of 3 works perfect. Going bigger would cause some to "block" parallel other waterways.

There are however several weirs in larger / wider waterways. There the multiplier is not enough (screenshot) causing water to pass the weir:

I could change the crest width, which is the proxy for the weir dam multiplier, to make it block the waterway. This however in turn would change the weir overflow through the weir formula. The actual current crest is correct.

Is there a way to have a weir specific dam multiplier? Can be done on the Tygron end. E.g. use the weir direction until it touches the sides of the waterbody, add a small margin and that would be the actual width. Obviously a maximum would make sense to avoid errors due to wrong angles.

I would also be able to calculate this myself but then again don't have an attribute to return it to. Is it possible to create this?

Other workaround solution I can custom make is using a combo overlay or other element to change the entire elevation model to have "dams" at all the weirs. But this would be a pretty severe solution and too complex for a lot of Tygron users as a general approach.

Hedi

Hi Len, your work-around solution is a good option at this moment. I have written down your suggestion as a feature request, which we will consider as an options for the longer term.

Len Geisler

Hi Hedi, thank you for the response. I'm not sure if the work around is going to work on the scale I need it to but good to know that this would be the road to go for at this time. I got over 1200 weirs here.

I think this could be something if more weir attributes become weir specific. Weir dam multiplier would be one. But weir move interval, weir move range and weir move step distance are also more logical as a weir specific project. In my current project I have over 200 weirs of which roughly half is a moveable weir. Some are manual, some automated. Each has their own movement range. Some around 40 cm others have way more range. One single value for all has significant impact.

For the specific weir I was looking at it does seem that it's capable of blocking water upstream even though the width visually is significantly less. Not sure how that works but glad it seems to work.