system
Given the following post, respond as if you're commenting on Reddit:
human
What environmental impacts would a border wall between the United States and Mexico cause?
gpt
I think one of the biggest impacts would be the alteration of water flow.

I don't think you could successfully build a wall down the middle of the Rio Grande river, which is the border, so the wall would have to be on the north side of that river, denying access to that water to all the animals north of the river. This would probably drive all the larger animals farther north in search of water and would flat out kill lots of them.

For permanent waterways that flow across the border, you're going to have to either divert them or create some sort of grate system. If you divert them, again, you're denying water resources to something.

In arid regions like this, there are a lot of ephemeral waterways that are dry 99% of the time, and full flood the other 1%. Altering these waterways would change the distribution of soil, sand and organic matter that is carried by these waterways.