D&D General Setting a campaign on a river

[Yora]

Would make a nasty surprise for people paddling upriver in their canoes.

 

[Ancalagon]

As others has suggested, Yoon-Suin may have good ideas for you, seeing as one of the main areas/culture is river-based.

I would also suggest that you check out the Deep Carbon Observatory. It's a "river based" adventure that is excellent.

DriveThruRPG

www.drivethrurpg.com

 

[bedir than]

Floods. Especially flash floods.

Since this is fantasy, the idea of flash drought popped into my head

 

[Yora]

Huge landslide blocks a river and diverts all the water into a different valley. I image water levels downriver dropping pretty suddenly.

 

[Stormonu]

Since this is fantasy, the idea of flash drought popped into my head

Oh, yeah - throw in magic and you can get some really crazy things - appeasing/dealing with water elementals, raise/lower water magically, parting water, transforming it (to wine or blood?) redirecting or stopping flow, troll bridges, tortle enclaves, sahaugin raiders, river mounts, kelpie or nymph abductions, fossergrims and their waterfalls, draughs (drowned zombies) and all sorts of other obstacles and encounters.

 

[Yora]

Raise/lower water actually becomes useful.

Ship can't get over an obstacle? Raise water.
Pursued by enemies with a faster ship? Lower water after passing the rapids.
Chest of treasure fell into the river? Lower water.

 

[Eltab]

The city upriver is new. Basically a trading post for all the peoples who live far upstream to collect their trade-able goods and send them down to civilized lands; conversely it is easier to haul all those manufactured goods to the half-way point upstream and meet everybody there, than to go the whole way up. This city is not (yet) part of the civilized culture-province; it shares influence from the several upstream cultures. See very early St Louis as a "sattelite" to New Orleans.
The city might be just below a cataract, where you have to unload and portage cargo around the rough stretch anyways. Smaller boats can (carefully) ride the flow downstream but, betwixt rocks and current, you cannot get upstream. See also Louisville on the Falls of the Ohio.

 

[AdmundfortGeographer]

The city might be just below a cataract, where you have to unload and portage cargo around the rough stretch anyways. Smaller boats can (carefully) ride the flow downstream but, betwixt rocks and current, you cannot get upstream. See also Louisville on the Falls of the Ohio.

Minneapolis and St. Paul exist as two separate cities because St. Paul was the uppermost site on the Mississippi for a river port due to a gap in the bluffs. Between Minneapolis and St. Paul the Mississippi runs through a 100-foot-deep gorge that was once filled with churning rapids that ended at a pair of massive waterfalls. (The rapids were later submerged beneath a dam that powered a now-gone Ford factory, the dam remains).

Minneapolis was founded at the waterfalls because the giant drop in the river here was perfect to power industry. Lumber and then grain milling (it’s why Pillsbury and General Mills were both based in Minneapolis). Minneapolis was industry, St. Paul was the river port, and there were trails linking the two.

There is precedent for a pair of towns, one the river port and another above the falls is industry!

 

[Undrave]

Here's something to think about: If your culture developped with a river as its main mode of transportation, then it will develop idioms and ways of talking that will related back to the river.

For exemple, they might not tell you to "Hold your horses!" but rather to "Moor your skiff!" or "Put down yer oar", the Bartender might call you 'Cap'n' instead of 'Sir', a friendly merchant might invite you to 'come aboard' his charriot instead of climbing in, and maybe they'll even use 'port' and 'starboard' on land instead of 'left' and 'right'. It's subtle but if your PCs are coming in from another country, it might add flavor to your culture.

 

[Yora]

I really like the idea of having a West Marches style public map that shows the known surroundings, to which players can add their own discoveries to share it with other parties. I could simply make a complete hidden map and just uncover all the rivers that a party has explored.
Having players attempt to draw their own maps as they go and the public maps accumulating errors over time sounds really fun to me, but without advanced surveying equipment, what would the characters even be able to scribble down? There's be no way to really track the distance covered over any number of days, and with a winding river it would be really hard to even tell the general direction you're going. Especially through a dense forest.

Any ideas how expanding the existing maps could be made into an activity for players?

One possibility would be to have players who want to map their progress make a navigation check, to determine how accurate their notes of their progress are. WWN makes skill checks with 2d6. You could have the player roll one die and the GM roll the other one, so the player can have an indication of how confident the character is in the accuracy of the notes is.
Then you also could have different maps made by different characters for the same areas, and players might have more trust in the maps of a character known to have a very high Navigation skill level.