LARKANA: The Sukkur Barrage authorities have advised the government to get the North Western Canal and its off-taking channels desilted on an emergency basis as the canal has silted up so heavily that its bed`s slope has changed, reducing its discharge capacity.

Sources in the irrigation department told Dawn that Sukkur Barrage right banl€s Chief Engineer, Mukhtiar Ahmed Abro, said in a letter to secretary of irrigation dated Dec 30, 2024, that heavy silt deposition on the bed of the N.W. Canal had changed its slope and altered the canal`s velocity and discharge.He referred to a letter he had received from Executive Engineer of Shahdadkot irrigation division on Dec 26, 2024, in this regard and said that N.W. Canal, a perennial channel, irrigated a massive area of 965,000 acres, including 184,000 acres situated in Balochistan province.

It was also a source of drinking water for the settlements located on its banks and they would suffer greatly if de-silting of the parent canal and its offtaking Khirthar Branch was not carried out immediately, he said.

He said that the N.W. Canal was 296RDs (reduced distance) long which came to around 59 miles and Khirthar Branch was 23 miles long. The unlinedcanal and its offtaking branches had higher potential of excessive silt deposition, said the letter.

The canal was originally designed for carrying approximately 9,600 cusecs but various studies and reports conducted from time to time had revealed that heavy silt deposition had seriously reduced its capacity to 6,700 cusecs, said sources in the department.

The canal`s offtal(ing branches were; Khirthar Branch, Ratodero Branch, Shahdadkot Branch, Salar System and over 60 other big and small arteries and tributaries, which were also major sources of drinking water for big populations residing in districts of Shikarpur, Larkana, Jacobabad, Qambar-Shahdadkotand a large area in Balochistan, said the sources.

The department also raised caution from time to time in its observations that the canal`s bed had been badly choked up due to excessive silt accumulation, especially from RD-0 to 83.5, which had largely contributed to water shortage during the last Abl(alani season, admitted Mr Abro.

He stressed that taking into account the obtaining conditions and factual position of the volume of silt on the beds of the canal and its branches, it had become inevitable to carry without further delay the de-silting work from RD-0 to 83.5 to help resolve the chronic problem of water shortage.Towards the conclusion of the letter, the officer sought permission from the Sindh government for carrying out desilting of the N.W. Canal on an emergency basis under Rule No.16 (b) (viii) of SPPRA Rules.

In two earlier letters dated Sept 11 and Oct15, 2024, addressed to the secretary of irrigation, Mr Abro had reiterated his call for carrying out de-silting of N.W. Canal immediately.

He said that despite replacement of Gate No.47 and repair of Gate No.44, the condition of the gates [forced them to] limit the extent of [water discharge] to maintain required pond level upstream Sukkur Barrage.

A detailed survey of the canalshowed heavy silt deposition that had drastically reduced the discharge capacity of the canal and its offtaking branches. Therefore, it was crucial to increase water supply to the canal as raising pond level beyond a certain point might also pose seriousrisks to the safety ofthe barrage, he cautioned.

The officer said that desilting of the N.W Canal and Dadu Canal, that would cost approximately Rs1678.365 million, needed to be carried out on an emergency basis so that the canals could be supplied water at the pond level of 197.5 feet as was evident from the desilting of Rice Canal, which carried the required design discharge at pond levelto198.0in2024.