Summoning of Enoch - Irrigation
[EN LX:21 PP] When the water is required from the Reservoir, the angels responsible come and open the sluice and let the water out. And when it has dispersed (as irrigation) over all the fields, it soaks into the ground.
[EN LX:22-23 PP] For these waters are for the benefit of those who live off the land; they are irrigation for the land, sanctioned by the Most High [Anu] who lives in the Heavens. Therefore, there has to be a measure of the rainfall, and the angels are responsible for keeping a record of the rain-gauge. These things I saw around the Garden of Eden.
Enoch was certainly aware that there was a Reservoir available for supplying irrigation to the plantations. A third passage on angel activities in the Garden involved measurement of a different kind.