Quite simple really. Water always finds it's own level so we have ensured water to Nature when the line is full. The Line is approximately one kilometer long. !
At this level we are at absolute minimum. Reason. ROOTS. !
We cut this pipe to minimum level - water is still flowing to the village. This pipe feeds Nature beside the Irrigation Line.
Roots removed and, once again, very high level, in fact, FULL.
Another FULL photo. ! When this tank is full we know that the first 750 meters of the Irrigation Line are clean and flowing well.