This is the base model of a water pump for the Shared Water Resources module.
The turtles do the drawing of earth, sky, and pump. Then the water in the ground is added with the "create groundwater" procedure using recursion. Next, water gets pulled by the force of gravity and gets drawn up into the pump (and used but this part of the cycle is not shown). Finally, the water is "recycled" as rain.
In this extension, the rate of evaporation is controlled by a slider.