If the flow rate or discharge of the qanat is sufficient, there is no need to store water, and it is transferred to the land directly. But if the discharge is not sufficient, it is then necessary to build a pool near the exit of the qanat in order to store the qanat water. The water in the pool is then transferred to the farmers' lands for a shorter time, but at a higher flow rate than from the qanat. If there is no pool, there is no possibility for people to use the water to irrigate their lands. Otherwise, the water cannot be transferred to the land efficiently and completely because of a high loss along the way to the cultivated lands.
