Why Can't A Dam Go On This Flood Plain?

[jsurpless]

The one two tiles to the east of my settler?

 

[Banazir864]

Dams can be really finicky sometimes. Assuming no one's built a Dam downriver, maybe the flood plain "belongs to" the northern river, but the southern river is considered the parent river, so the northern river only touches one side of the tile instead of the required 2+ (and the three sides after the fork don't count because they're the "wrong" river).

 

[Eagle Pursuit]

Just a guess, but the river it's a floodplain of is the one coming down from the north. And it only has 1 of its 6 sides against that river. You need to have 2 sides against the river it names.

Ed: ninja'd

 

[Troy Bruckner]

We should be able to build a damn on any river tile except mountains of course.

 

[Dearmad]

My guess is someone beat ya to it downriver? or it has to do with the river's bend there.

 

[TheyMadeMeDoThis]

Tile may have a hidden strategic resource on it.

 

[Tech Osen]

I had a situation a while ago where I had two rivers joining. I thought I had room for two damns and could get some nice adjacency for IZ. But the first dam I placed had two sides on one river and one side on the other. I didn't realise that until I wanted to place the second one some time later. I was not amused.
You really have to pay attention when placing those things. Had it happen more than once that I left a spot for a dam only to realise it only had one river side after I build stuff on alternative spots. Or worse: leaving a proper spot and then iron or niter pops up right there.

 

[qadams]

Yeah, that happened to me too recently. I'd found (I thought) the perfect position for a dam, on a flood plain between two IZ's — but when I later tried to build a dam there, none of my three surrounding cities could do so. I think it must have been because of what Eagle Pursuit and Banazir said above, that the tile had only one side on the river which "owned" it.

That's a ridiculous limitation, totally unrealistic and counter-intuitive. Also extremely frustrating for players. There must be some way to fix it.

 

[jsurpless]

Just a guess, but the river it's a floodplain of is the one coming down from the north. And it only has 1 of its 6 sides against that river. You need to have 2 sides against the river it names.

Ed: ninja'd

This is what it is... since a tile can (stupidly) be only assigned to a single river, it's assigned to the Wallaqa Maya river and thus only has one tile on it, whereas it has two tiles on the Putamaya river

 

[Banazir864]

The really frustrating part is that the Dam graphics don't actually seem to care about which river owns the tile, making this restriction pointless: I recently had a game where I placed a Dam on a V-shaped fork (with two edges on the parent river and two on the tributary), and even though the Dam "belonged" to the tributary, the graphics made the Dam appear on the parent river. As a result, it looked like I had two Dams on the parent river and none on the tributary (which was a bit frustrating because I'd rather have placed the second Dam on the tributary, so if it had actually counted the fork Dam as being on the parent river, I could have gotten better IZ adjacencies). I've also seen screenshots with parallel rivers where a Dam appeared on the wrong river.

In that same game, I also found a lovely valley with three rivers and lots of flood plains, but only after settling my three cities did I notice that all of the flood plains belonged to the same river.

 

[Bibor]

I have an idea, can you provide us with the seed numbers and map settings?

(copy the save into the 'multi' folder, create a new mutliplayer game by loading that save)

 

[Eagle Pursuit]

I'm fine with the restriction. In reality these aren't dams, they are a system of levees or a weir. That's what controls flooding on flat land.

In reality Dams aren't built in floodplains, they are built in narrow valleys, canyons, ravines, or some other bottleneck that allows the natural formation of the earth to do most of the work containing the reservoir.

 

[Tech Osen]

I'm fine with the restriction. In reality these aren't dams, they are a system of levees or a weir. That's what controls flooding on flat land.

In reality Dams aren't built in floodplains, they are built in narrow valleys, canyons, ravines, or some other bottleneck that allows the natural formation of the earth to do most of the work containing the reservoir.

For the reason you stated in the second part I'm actually not fine with the placement restrictions. You don't build a hydroelectric dam on a levee. It would make more sense to have to build them between two hills and/or mountains.

 

[jsurpless]

I have an idea, can you provide us with the seed numbers and map settings?

(copy the save into the 'multi' folder, create a new mutliplayer game by loading that save)

458461568/458461569 - Seven Seas, Gathering Storm, Resources Abundant, World Age New all else standard

 

[steveg700]

Dams require at least two sides to have rivers. Sorted.

It's annoying sometimes, but the game needs to present players with tough choices. The requirements for the national park diamond are way more aggravating IMO.

Anyone who's ever played Cities Skylines would know you don't put the dam directly onto a floodplain. Bad things happen.

 

[Bibor]

Okay, I tested it, and it's much simpler than I thought. I.e. they have been lying to us!

One dam per flood basin. River junctions, multiple rivers. Doesn't matter. If it floods together, it's one dam. A river can be 100 hexes long, you can have either one dam or 30.

For a dam to have a valid placement, here's what you need to do.

First, check if the river is floodable. It requires 2 hex-lenghts for the river to flood (4 floodplains).
Separate rivers have separate floods if they don't touch.

Next, check that both sides of the river are a floodplain that can flood. If the answer is yes, you can place a dam on either hex (except if one is a resource).

Next, mark pairs of hexes starting from the right side of the river (looking downstream) that can flood. Any odd number hex -you won't be able to build a dam there.

In the OP's screenshot, there are 6 hexes that can flood, and the 7th does as well, but opposite of it is a plains/volcanic tile, not a floodplain. No dam there.


So, the full requirements for building a dam are:
1. One dam per flood basin.
2. Hex must be touching a river with 2 out of 6 sides. Of these two, one must be a floodplain.
3. Hex must have a teamed up hex that can also flood, counting from start of the floodplain set (from source downstream).
4. Any hex that can't team up with another hex (in case other hexes are alread teamed up), can't build a dam.

 

[jsurpless]

Why is that 'across the river' has to be NE/SE?

 

[jsurpless]

I am not able to build a dam on the tile to the SE of the Qurupuna volcano - is that because I built ToA there? Must be cause I can't build a damn to the NE of the Govt District either

 

[Tech Osen]

Tile SE of the volcano only has one river side, needs two. The other one I can't see properly, popup text covering it.

 

[jsurpless]

Tile SE of the volcano only has one river side, needs two. The other one I can't see properly, popup text covering it.

Ahhh, yes... thanks!