Is there a way I can read values of a height map from a shader graph?

Hey there, first off thanks for taking the time to read. Here's what I am trying to accomplish: I've created an ocean shader using shader graphs, and I would like to be able to adjust the wave amplitude dynamically, based off the depth of the ocean. Waves closer to land would be smaller, while those in deeper waters would be larger. My current conceptual approach is to have a height map of my terrain the shader graph will look at and adjust the wave amplitude based off the height value at that vertex's position. So my question here is, can you think of a way to accomplish this? Also, if you have a better approach please let me know. TIA