What is the ruling if the water volume diminishes to an amount insufficient for the crop?

Primary text

If the water diminishes to an extent insufficient for the crop, the lessee has the option to dissolve the contract because this constitutes a defect. If this occurs after the planting has already taken place, the lessee still has the option to dissolve the contract. In such a case, the crop remains on the land until harvest, and the lessee owes the stipulated rent proportional to the period until dissolution, plus the customary rent (*ujrat al-mithl*) for the remainder of the term for land requiring that same water level.