ISLAMABAD: Farmers belonging to the command area of Machai Branch Canal of the Upper Swat Canal (USC) System are reporting accumulation of silt/sand in their fields since the operation of canal after the last year’s devastating floods in Swat River, which is not only lowering withdrawal of design discharges in the off-taking distributaries and minors canals but also affecting deterioration of the soil texture and water supply to the fields.
To address the issue, farmers of the affected areas have demanded of the Irrigation Department of Khyber Pakhtunkhwa to thoroughly investigate the problem and immediately embark on the remedial measures to save poor farmers from colossal financial losses by permanently rectifying the defects and operational issues of the canal system.
Khan Faraz, former Secretary, Pakistan Tobacco Board said that that like all planned irrigation canals, the Main canal of USC system has a well-designed Silt Ejector / Vortex tube which is used for silt exclusion from the main canal to allow entry of silt-free water in the irrigation system. To address the issue, farmers of the affected areas are demanding the Irrigation Department to thoroughly investigate the problem and immediately embark on the remedial measures to save poor farmers from colossal financial losses by permanently rectifying the defects and operational issues of the canal system.
Faraz further said that River Swat is the main source of irrigation water supplies for the four major districts of Khyber Pakhtunkhwa i.e. Mardan, Charsadda, Swabi and Nowshera. It originates as Ushu and Gabral rivers in the Kohistan range of northern mountains of Khyber Pakhtunkhwa and takes the name of River Swat at Kalam at the confluence of the two rivers.
Panjkora River from Dir Valley joins the Swat River downstream of Totakan. There are two major offtakes from the River, Upper Swat Canal at Amandara and Lower Swat Canal at Munda. Apart from these two major off takes, hundreds of civil canals are off-taking from the Swat River all along its length, he added.
Commissioned in 1914, the Upper Swat Canal (USC) takes water from the Swat River at the Amandara Headworks. It was originally designed for a discharge of 2,420 cusecs to irrigate an area of 315,000 acres of the Charsadda - Mardan - Swabi Plain.
The canal, after traversing the narrow ridge of Malakand hills through the unlined Benton Tunnel, eventually bifurcates at Dargai into the two branches of Machai and Abazai.
Soon after construction of the Benton Tunnel in 1914, it was noticed that, though constructed to the full design section, its discharge capacity was not more than 1800 cusecs due to its unlined nature and surface roughness.
Due to this constraint, the authorized full supply discharge of the canal was fixed at 1,800 cusecs and the Culturable Command Area (CCA) reduced to 276,000 acres.
The system was remodeled by construction of an additional Auxiliary Tunnel under Mardan & Swabi Salinity Control and Reclamation Projects (SCARPs) in 1998, enhancing its capacity and water allowance to bridge the gap between supply and demand. This increased the design annual cropping intensity from 120 to 185 percent.
About 75 kilometer length of USC (RD 0 to 242) was remodeled under the Swabi SCARP, while the remaining portion of about 50 kilometers was remodeled under the Pehur High Level Canal (PHLC) Project in 2002, Faraz added.
Copyright Business Recorder, 2023
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