Hmm, that does not sound like a project in the manner Merlin Project sees it. Meaning you don't put water into the line, and then you are done and do something else... it feels more like: I have stuff (resource water) and need to weekly schedule it not for specific tasks with a start and an end, but for just being there, available and doing what ever needs to be done within specific time periods.
If I were to schedule something like this in Merlin Project, so I know when the watering of drip line A, which fills for example a pool which then allows me to use the water for another work, or start another kind of activity leading to yet another (so not a periodically repeating thing…) I would…
- Create a calendar with the water availability
- I would create a water material resource by an Available (max rate of) 1200litres/hour
- I would map the water resource to the water availability calendar
- assign work with pipes to it.
- on the pipes of different flow rate I would set the resource unit of the assigned resource to match the flow rate; 12 litres/hour, 569 litres/hour, 1000 litres/hour and the given work 50, 1250, 3250 litres
- Modify the Time Phase in Assignments > Work distribution to show Expected Utilization
That would show if my water is over allocated, and how long the pipes would need to provide the needed amount of water.
After that I could link the finish of those pipes to a milestone for the next works to start.
I attach screenshots for you to check and hope I could help a bit.