Calculate stable water level use case (Water Overlay)

For water management purposes it can be relevant to know how water will stabilize throughout the system. This can be in a default situation, where there is a nominal amount of water in- and outflow. This can also be in a situation where the system is under duress, such as with a consistent amount of rainfall. There are multiple possible definitions of a stable water system, but a common characteristic is that the inflow and outflow match up, leading to either a consistent amount of water in the system or a predictable water rise/fall at points of measurement.