Global Mapper v25.0

Increase water level behind artificial dam


I have manipulated a terrain and created an artificial dam. Now I would like to know the maximum amount of water that can fit into the gorge behind it. However, I can't get Global Mapper to start increasing the water level from my self-created dam. The water level is always increased on the basis of the sea level or a water area layer. There is no water yet.

Is there a suggested solution for this?

Thank you! 😁