Ideas for building a house in a depression

And what exactly must be done against it?

And what exactly must be done against it?

Sealing, drainage, gutters... there are a variety of measures that again depend on your property and your construction project. You should coordinate this with the construction companies in question. And better a little more drainage and sealing than even a tiny bit too little.

Would something like a slope of about 2-3% downward 1-2 meters away from the house (so 4 to 6 cm over 2 meters) and then rising again (e.g. at Michika then rising 38-40 cm instead of 34 cm) not work? The water would then flow away from the house, right? It might stand at about 2 meters away, but maybe there you would create a slope again to the side!? Just a layman's idea from me.