How to create this contour form ?

 From:  Kwin
10161.1 
Hi
I am very new for MoI3D.
Anyone can guide me how to create this hill ?

I have tried loft , sweep , revolve rail, but all not work as I would like to do3
Loft can create surface but can follow the rail.
I attached this model file here as well.

Thank you very much









Image Attachments:
Size: 1.8 MB, Downloaded: 9 times, Dimensions: 2017x1870px