THIS refers to the letter ‘Farmers ask for brick-lining of canal’ (Dec 8). The farmers in Toba Tek Singh complained that water in Trimu-Head Sindlai Link canal is 12,000 cusecs compared to 40,000 cusec capacity.

This is causing water-logging, destroying the rice plantation. There is no fodder for animals and they are dying. The people working in fields have migrated to cities and are doing labour jobs. Not knowing any other option, poor farmers want brick-lining of the canal to control water seepages.

Although brick-lining may reduce seepages, it will not isolate them. PVC geomembrane is the best option to control such leaks. The Hub canal supplying drinking water to Karachi used to leak profusely.

The seepage was 44pc. After lining with PVC geomembrane, the losses came down to less than 3pc which is the evaporation loss.

This job can be done quickly and economically. No bricks, cement mortar or hundreds of masons are required to do the job. The same thing is being planned for the 11-km segment of Rohri canal, near Nawabshah.

S. Nayyar Iqbal Raza

Karachi

Published in Dawn December 18th , 2014