system
Given the following post, respond as if you're commenting on Reddit:
human
What are the long term consequences of forcing our rivers to stay on the same path?
gpt
The effects vary wildly depending on the location and river and it is a very complicated topic, but here are some basic impacts.

Ecological impacts are almost always involved. Often man-made barriers that prevent river convulsion or migration are much different than the natural river banks, and so it can easily completely disrupt the local riparian ecosystems (which can then impact other nearby ecosystems). There are low-impact ways to keep rivers on the same path, but they tend to require a lot more money, planning, and maintenance, so they are not always used.

Redistribution of sedimentation is another major impact. Rivers will usually be forced to stay on a single path in places where they are depositional, rather than erosional (since erosional portions of rivers are usually highly channelized naturally). In most cases, rivers naturally build up sediment in one location until the channel becomes unstable, at which point they will convulse to a different location on the flood plain and start building up sediment there, and so on. Forcing a river to one location will force the sedimentation to only occur in one place. This can be problematic for a whole slew of reasons, but one famous example is with New Orleans. Naturally, the sediment from the Mississippi would offset the subsidence of the area. But since the river has been constrained, the sediment is all transported offshore. Because the city was built on this subsiding land it is now below sea level and at a huge risk from flooding. Which is why it is the home of the most expensive natural disaster in the United State's history.

Also, forcing a river to follow a single path usually means you make the river "straighter". Such as taking a meandering river, straightening it out, then using the extra land that creates for development. But this effectively increases the gradient of the river, which can have major impacts on upstream and downstream sedimentation and erosion, which can be problematic and expensive. The process of channelizing a river can also change how it transports and processes pollutants.

Of course, forcing a river to a single permanent channel can also do a lot of good for nearby human communities, and in some cases can help with ecological conservation efforts. So it's complicated.