Orient multiple curves

Hi to everyone, i have a problem right now i'm tryng to create a landscape made of concave and convex elements... so i taked the curves in plan, projected on the plane... made a series with scale and a series with move whit the aim of joining togheter the shapes with a loft... the problem is actually that insted of taking the referenced surface on wich i projected the geometry it creates orizontal curves.... as you can see in the image...

is possible to find a solution for this...?

i don't know maybe rotate the curves according to the slope of the terrain...?