help edit new Terrain Improvement -- Dam / Dike

[FWCain]

The ancient Romans were masters of civil engineering. They built a vast networks of roads, stretches of which survive and are usable to this day! They also built bridges, and aqueducts and canals, and planned cities (Towns?) with paved streets and covered sewers. They also built dams.

And in the Netherlands, the Dutch have built dikes over the centuries, allowing them to claim lands that were once seafloor, giving them more farmland.

If a Kingdom (whether in the Kingmaker Adventure Path, or in Ultimate Campaign's kingdom building rules) can build Roads, Highways, and Bridges, with Canals and Aqueducts, that kingdom should also be able to build a Dam/Dike, whether to divert the flow of a river to change its course, or to stop up its flow entirely (resulting in a new lake).

But this kind of Terrain Improvement can (and realistically _should_) result in an actual _change_ to the terrain itself, necessitating the Game Master editing his game's map accordingly.

So, I ask you, how should such an option be codified into the rules? Any ideas or suggestions?

Thanks in advance! ;-)
Franklin

[FWCain]

My initial thoughts are, this option's price should be proportional to that of a Bridge in the Terrain Type in question, but several times higher (maybe three to five times as much as a Bridge, which itself is double the price of a Road).

The exact result of such a project (i.e.: how it will change the map, etc.) would need to be discussed between the GM and the player(s).

Franklin

[Andostre]

What benefit would the PCs' Kingdom receive by building a dam or dike? I think answering that would inform your other questions.

Off the top of my head I can't think of a beneficial reason (in terms of game rules) for altering a river.

[Ben Walklate]

I've had a look at this, and from the perspective of the scale of a kingdom hex, a dam would have zero effect on the kingdom rules mechanically, because you are unlikely to be able to alter the course of a river enough to even be noticeable at that scale, and a lake has no effects that a river doesn't already have. Given that such a change would be purely aesthetic, 1 BP to divert a river, 2 BP to create a new lake wouldn't be unfair.

For dikes the hard part is that coastlines are considered the adjacent terrain type for the purpose of terrain improvements, so you can already build anything you want. You'd need to cost up actually changing a 93 mile squared change of terrain type, and that would be expensive. Not an unreasonable houserule, though, so I've discussed with my players and we crunched a few numbers. We think that it taking 2 turns to complete and using up an edict in both of those turns, with a cost of 12 BP would be a not-unreasonable amount.

For those interested in the crunching, for the purpose of this, the increase in population the kingdom sees has negligible effect, the true benefit is from changing a hex from water to land and the ability to build farms on it. Given that the sea bottom is by definition low-lying, only allowing the hex to become a plains hex makes sense, which then has a cost of 2 BP to build a farm on it. So far, you've spent 1 BP to claim the hex, 12 BP to turn it from water into land, and 2 BP on a farm, so 15 BP. A farm reduces consumption by 2 BP per turn, which effectively means a hex with a farm in it reduces the kingdom's consumption by 1 BP per turn, because the hex costs 1 consumption. So, the farm starts to provide actual benefit to the kingdom 16 months after it's completed. That seems pretty fair to me.

Feel free to play with that 12 BP cost, but that's the theory to help out.

[FWCain]

I forgot to mention the use of levees and embankments. to wall off and drain swampy terrain for other uses (for ex.: New Orleans).

There are a number of hexes in the Hooktongue Slough (AP #34) that could be converted by this means into usable farmland (i.e. converted from Swamp to Plains). Of course, this means that floods would be a logical choice for any detrimental kingdom-level Event in the future.

Thanks for the feedback! ;-)
Franklin