ISLAMABAD, Sept 11: The provinces have agreed to change the decades-old water distribution mechanism and accepted a new arrangement under which Punjab’s maximum requirement will be met by Mangla Dam and that of three other provinces by Tarbela.
The change is significant since a water apportionment accord signed by the provinces and the federal government in 1991 had fixed provincial water shares on the basis of anticipated annual water availability of 114MAF (million acre feet).
Under the accord, the provinces received their share of water from a combined storage pool and link canals, like Chashma-Jhelum and Taunsa-Punjnad, were utilised for diverting water from the Indus zone to the Jhelum zone.
As a result of the fresh arrangement, the Indus River System Authority (Irsa) has decided to drastically reduce diversion of Indus flows into Jhelum zone through Chashma-Jhelum (CJ) Link Canal and undertaken increased releases from Mangla dam to meet Punjab’s requirements.
An official told Dawn that the CJ Link Canal’s intake from the Indus Zone was being gradually scaled down from 18,000 to 3,000 cusecs and only the quantities reduced would meet the requirement of the Greater Thal Canal.
After initial reservations, Punjab accepted the new arrangement after a three-day visit by a three-member delegation of Irsa to Lahore which convinced the provincial authorities that the revised mechanism would be of benefit to all stakeholders in view of the improved storage capacity of Mangla.
The Punjab and Wapda authorities were initially of the view that Mangla should be filled to its maximum capacity of 7.3MAF, instead of closing down the CJ Link Canal.
Mangla’s conservation level has been increased from 1,212 feet to 1,242 feet this year after raising the dam’s height.
But the Irsa delegation explained that Mangla could not be filled at the cost of depletion of storage at Tarbela given the fact that less than 0.2MAF of storage capacity was now available at Mangla.
In order to increase storage at Mangla, the delegation said, Irsa had to reduce water level at Tarbela by four feet a day which would not be in the interest of any province, including the Punjab.
Diversion of Indus waters into the Jhelum zone requires higher discharges because of higher losses along the CJ Link canal.
It was, therefore, decided that the extent to which Mangla dam had been filled was enough for the current year so that drawdown from Tarbela was contained when flows in Indus and Kabul rivers drastically came down. As a result, the Sindh government has also reduced its indent from the Indus to 130,000 cusecs from 150,000 a day earlier.
The conservation level at Tarbela has come down from a maximum of 1,550 feet early this week to 1547.15 feet on Wednesday, according to sources. The change in water distribution mechanism was made because of upgradation of Mangla as the country’s largest reservoir that has the capacity, if completely filled, to meet full requirement of the Punjab irrigation with lower water losses, except in exceptional cases.
The irrigation requirements of Sindh, Balochistan and Khyber Pakhtunkhwa would be met from Tarbela dam.
The arrangement would be formalised during the forthcoming Water Distribution Plan for Rabi -- beginning on Oct 1.
On Aug 23, Mangla Dam became the country’s largest reservoir overtaking Tarbela’s top position when its storage crossed 6.5MAF.
On Wednesday, Mangla’s water level exceeded 1,239 feet with storage of a little over 7.1MAF — only three feet below its maximum conservation level of 1,242 feet. Mangla Dam raised by 30 feet would now have a maximum storage of 7.3MAF when filled to capacity at 1,242 feet — an addition of about 2.5MAF.
Balochistan’s complaint: Balochistan has again complained to Irsa that Sindh is not releasing its full share at Garang regulator. In a written complaint filed with the water distribution authority, the Balochistan government said the province was being provided 1,600 cusecs against its share of 1,800.
Irsa directed the Sindh government to immediately address Balochistan’s complaint and release its full share. At a time when substantial water was available downstream of Kotri and Sukkur barrages, the authority said, it was not appropriate for Sindh to deprive Balochistan of its due share.