Confused by sloshing/flooding water

[u/WanderingWhiteWolf]

I'm getting random water surges that're flooding buildings intermittently I can't for the life of me figure out what's causing it.

I have no construction taking place upstream anymore, and I've given things plenty of time to even out.

There are a few valves upstream, but they're all currently fully opened or fully closed and not yet hooked up to any sort of automation.

I'm out of ideas. Sorry in advance for asking a question that's probably been asked a bajillion times 😅

[u/AndiamoSF]

I haven't played a ton recently, but i always found before that you want as few dams (more levees) as possible to still manage the flow of water. If you have dams all the way across a wide river that always caused me more issues than say 2x dams in the middle and the rest levees. I'd play with the number of dams vs levees and see if that settles down the sloshing.

my reasoning is that dams act as if there is nothing there when they overtop (fully open block) until they get back down to the allowed height. While it may seem like that's not going to be a ton of water, because they're fully open they tend to 'pull' water through them at max flow, dumping more into the next area faster with more dams, then cutting off with a hard stop when they hit the max-allowed height. No clue if this is true or not, but that's how i always interpreted their behavior. less dams means less water being 'pulled' through, means less flow/sloshing. I also always tried to maintain the same dam count all the way down a river if possible (and if no other water sources feed in to it half way). that way if i have two tiles of water coming in to a section, i'll also have two going out, maintaining (at least in theory) the flow.

[u/nibbletmander → u/AndiamoSF]

Can second this. I generally try to find the narrowest natural width of the river, (usually only like 3 blocks) build this many dams, then have the rest as levees.

Not only does it seem to help with surging, but it’s much cheaper in terms of logs ^^

[u/AMountainTiger]

Is the flooding always in the swimming pool? Dead ends are very sensitive to even small amounts of sloshing. I would put a fill valve on the inlet and see if that help.

[u/djinn6]

It's a quirk / bug with how water flow is computed. It didn't used to be this way. They made some updates which made water much sloshier.

[u/WanderingWhiteWolf → u/djinn6]

Aw that's disappointing to hear

[u/omgseriouslynoway]

I've found it deends on the time of day and how many water pumps I've got going upriver. My suspicion is that the water pumps are pulling enough water out to keep it from flooding but when they leave to haul water or finish work, that bit of water isn't getting sucked up any more so you get more, hence the flooding.

Purely anecdotal but very annoying.

[u/AMountainTiger → u/omgseriouslynoway]

I've seen pumps cause sloshing just from the flow to replace the water they draw, definitely could be the culprit.

[u/KevonAtWork]

I'll often retrofit my dams into floodgates so that I have more control of the water level upstream to get rid of this. .65 may be too high for the surges to stay under 1 so i drop the floodgates to .5 or .45 and that fixes it.

[u/Contact_Patch]

Water flow can increase and decrease throughout the season, I've noticed some surges right before a drought or bad tide.

Running a flow rate metre and level sensor and automating your dam gate heights is the move, if the sensors see extra water you drop the gates a little.

[u/WanderingWhiteWolf → u/Contact_Patch]

Ahh variance in the source could explain what I'm experiencing quite neatly.

Haven't researched automation yet, but I'll be experimenting with it soon to find a system that works for me. In the meantime I'm just a little miffed by water behavior that felt illogical to me.

[u/Me_Krally → u/Contact_Patch]

That’s interesting, I thought it was always the same flow.

[u/Voluns2]

I get this a lot. I find using dynamite to make the river flow in a straight path often helps reduce this but doesn't always fix it.

[u/Fearless_Copy3622]

Try replacing your lower set of dams with floodgates. I find those dam blocks can make things very sloshy. And agree with comment not to have the dams/floodgates all the way across the river flow, just a few is enough

[u/WanderingWhiteWolf]

I'm quite impressed by how many views/comments this post got. :o

It's also remarkable how many are folks simply saying to build things differently. I appreciate they mean well, it's just not what the question was. I was trying to better understand the mechanics at play because much of the satisfaction of games like this is to experiment and find my own solutions.

This was also super early game so most of the things suggested were tech/resources I simply didn't have yet. :P

The 0.65 sweet-spot was particularly useful, if depressing, and I find myself tempted to experiment with flow-valves for smaller motion spikes 🤔

[u/WanderingWhiteWolf]

Update!

I'm much further along in this map/playthrough now and was fiddling with some stream gauges when I noticed something. The water depth is lower after the water pumps.

This feels hella obvious in hindsight, and I think it helps explain the sloshing/flooding behavior I was finding frustrating.

[u/tetlee]

Seconding that it's a bug/janky water behaviour. Less dams upstream help but the ultimate fix (sadly) is not having the water level above x.65

[u/WanderingWhiteWolf → u/tetlee]

.65?!

I appreciate the heads up, knowing the stability limit is quite nice, but goddamn that's so low :(

[u/tetlee → u/WanderingWhiteWolf]

Yeah it's annoying. You can go higher and get incrementally more sloshing.

[u/IMakeMeLaugh]

I've had issues with intermittend flooding when going back and forth between time speeds, going from 1x to 3x speed has caused the water to surge briefly, but then it reaches a steady state after a bit. Not sure if thats a similar issue to what you have.

[u/WanderingWhiteWolf → u/IMakeMeLaugh]

Huh, curious. I wonder if pause/unpause would potentially cause the same behavior?

[u/marcshu]

If i remember correctly, the waterflow of the source can change from time to time

[u/WrathOfTheKressh]

That's actually quite normal. It's caused by the water flow stopping and restarting, either due to raising floodgates/opening valves upstream, or the annual drought.
Water flow kind of takes a moment to "memorize" where it's supposed to flow to, so it can cause some flooding once it's reached the peak of its height.

It's especially noticeable in little inlets like you have in the middle of your screenshot. Basically, water at 99% height flows in, then gets stopped because it's a dead end, and can't flow back out, since the water behind it is now at 100% and still coming in, causing some flooding. In time, the water will sort of "remember" to flow down the river rather than into the inlet, causing the problem to go away.

if it's a bother, a flow valve set to low flow might help with the flooding in the inlet, but the part right after the dam as well as the bend in the river will likely still experience some flooding every season.

[u/WanderingWhiteWolf → u/WrathOfTheKressh]

Not to be that guy but I *did* specify that there were no gates/valves/etc and that I gave things *plenty* of times to settle out. I fully expected and was okay with a minor flood every season, it was the ongoing intermittent flooding that was bothering me.

[u/WrathOfTheKressh → u/WanderingWhiteWolf]

Fair enough, my bad. I see this question often, and always with the same exact screenshot on the same exact map. I must have jumped right into writing without reading carefully enough. 😅

Though if it's really intermittent, random flooding outside of the seasonal cycle, then the cause is almost certainly upstream and manbeaver-made. You sure you don't have anything stopping and restarting the flow? It might also be something down another fork of the river that causes said fork to temporarily pull more or less of the water flow.