Surface modelling: Surface react to second surface?

Hi guys, again I have a small problem which i want to discuss with you before i start wasting hours :D.

So, I have to surfaces -One would be the landscape, the second one a road.

I want now, to achieve, that the landscape adjusts itself to the road when it intersects and comes together. 

I made a small sketch, I think, a pointgrid has to react to the surface, but I`m not really sure.

Feel free to help :D, probably its a total noob question.

cheers 

timsel