What are the demerits of canals? How to overcome these defects?
(i) Salt effervescence: The cultivators misuse canal water by overflooding the fields. It leads to salt-effervescence which makes the soil infertile. The farmers have to be educated in the careful utilization of canal water.
(ii) Water-logging: It is a serious problem which has rendered extensive area unfit for farming. The canals are generally unlined. Hence water seepage towards the adjoining areas goes on, turning them into swamps. For solving this problem:
(a) Canals should be lined with brick and mortar along the embankments.
(b) Wells may be dug in water-logged areas so that the water may soak down into these wells.
(c) Swamps may be dried up, by draining out the water with the aid of power-driven pumps.
(d) Gypsum can be used which makes the soil fertile again.