I would guess that things like dams built of substandard materials need more maintenance than if built up to spec. If you then mobilize the lower-level workers who would otherwise have been doing that maintenance do other people step in to do it? I would guess it goes undone - particularly in a 'low trust' society.
Earthen dams (probably 'puddle mud' but if they were going to use earth in place of concrete why would they build the sturdiest kind of earthen dam?) need a lot of looking after.
So... disasters *could* be increasing.