Outdoor area/flood zone to building land? (Lower Saxony)

What possibilities would there be for such a category of land / property?

Everything that is permitted in the outer area. Agriculture, horse breeding, gravel pit, etc.
So not usable for ordinary mortals.

That's true, and I have also read through some of them. But in the end, it often comes down to the exact local conditions, and "floodplain" was usually not included ;-)

And because of this unique penalty point, the other cases—where our predictions for the time horizon range from about twenty years to never ever—will all have relatively even more expectation for transformation than your case.

Everything that is allowed in outdoor areas. Agriculture, horse breeding, gravel pit, etc.

I looked it up now, but found nothing. It is always about building houses/sheds/etc., but not about such alternative scenarios. Is there an official list/enumeration/laws/paragraphs, or a site that describes this well? Horse breeding: As far as I know, no stables may be built. However, horses are already there, and I think some old makeshift stables might possibly have grandfathering protection? Gravel pit: My grandfather did that professionally :-) Leased fields, extracted sand/gravel, returned fields...

Addendum: It is mainly about buildings, right? Would we be allowed to build a huge swimming pool?? :oops::cool::D (Not meant seriously, serves more for understanding)

I have searched now, but found nothing. It’s always about building houses/sheds/etc., but not about such alternative scenarios. Is there an official enumeration/list/laws/paragraphs, or a page that describes this quite well?

See the following paragraph in the Building Code:

Thank you, I already knew that. It is not completely clear to me how "Vorhaben" is defined. It is in the "BAUgesetz". So everything is allowed that is not related to 'building'?

- A proper swimming pool, then, not allowed because it has to be built?
- Horses (without a stable) can be kept on it
- Elsewhere I have seen, for example, that caravans are also not allowed because they are considered permanent buildings and thus fall under building law (unless you move them down every day)
- What about, for example, a terrace made of gravel?
- Vegetable cultivation (the word "bau" is in it too ;) )
- Could I dig a hole for a large pond (someone mentioned gravel extraction above)?

Not that I intend to do these things, but it's just not completely clear to me...