Are they Polylines? If you want them to flow in curvy ways instead of having abrupt angles, try PEDIT and either the Fit or Spline option, but watch closely what happens, because it may change things in a way that you don't want -- it will be affected by various things, such as whether there are any intermediate vertices within the straight stretches. You can also round sharp corners using Fillet, which has a Polyline option that will apply the same fillet radius at all corners of a selected Polyline at which it's geometrically possible.
Hi,
Do you really want to smooth that contour lines?, they looks like a dam or dike, and so they represent physic reality beyond the aesthetic.
Gaston Nunez