Can I prevent catchments from moving or being edited so I can move other elements without misaligning the catchments?
Can elements be locked from being moved or edited?
No, currently elements can't be locked for editing, however there is an open enhancement for this request 331662. The workaround is to turn off the catchments temporarily in the element symbology while you work with the other elements. This is done by unchecking the box in front the element in the element symbology. See screen shot below.