How could the rerouting of a river affect the surrounding lowland?

the land no longer floods, so it has less nutrients

the land floods more, so it has more nutrients

the land becomes a lot dryer, so plants die

the land becomes a lot wetter, so plants die

Question

How could the rerouting of a river affect the surrounding lowland?

		
the land no longer floods, so it has less nutrients
		
the land floods more, so it has more nutrients
		
the land becomes a lot dryer, so plants die
		
the land becomes a lot wetter, so plants die

trancenova · Answer

I think the main effect is "the land becomes a lot dryer, so plants die"