Manchhar lake: a disaster in the making?
By Shaikh Aziz
KARACHI: The water level in the Manchhar Lake, Dadu district, has reached a dangerous high and although a round-the-clock vigil is on, a disaster cannot be ruled out.
The water level has already touched a mark of 113.9 RL, causing seepage at four points. A number of villages lying near the embankment stand waterlogged. And if the embankment gives in to the torrent, it will not only devastate large areas in Bubak, Sehwan and Bhan Syedabad, but also the highly toxic water will advance up to Hyderabad and down to the delta. This is likely to leave a trail of devastation -- both in terms of human life and damage to cattle and crops.
The discharge of lake water began on Dec 10 and at present 390 cusec is being released thrown into the Indus in order to lower the lake level. Before the water discharge began, a meeting of experts decided on Dec 7 to release water at a ratio of 1:50 as the lead content stands at 5,000mgs instead of 500mgs while the magnesium content is 700mg instead of the normal 30mgs.
In 2004, when toxic water of the lake was discharged into the Indus, it brought death to 42 people in Hyderabad, sent hundreds to hospitals and caused a substantial damage to vegetation in lower Sindh. The situation may deteriorate after Dec 25 -- when the canals of the barrages would resort to rotation, stopping the discharge from the two barrages for general consumption.
The issue of throwing toxic water into the Indus goes back to the construction of the Right Bank Outfall Drain (RBOD), which brings saline water from upper parts of the country. The Manchhar lake system is based on a natural fill-and-discharge. The system works in a manner that during the flood season the Indus water fills the lake through Aral canal. And during
the off season -- when Indus gets lesser water from Sukkur Barrage -- Aral releases the lake water back into the Indus to meet the shortage downstream Kotri.
Since the commissioning of a part of the RBOD in 1982, the Manchhar has been taking a much longer time to fill. But in recent years when the lake failed to get the required fresh quantity of water, the ratio of toxic water increased. And when this toxic water was released in 2004, it wreaked havoc in Hyderabad and other towns that get drinking water from the Kotri Barrage and Kotri waterworks.
Many people died and cattle and agriculture below Kotri Barrage suffered. After an intensive study, it was decided that the quantity of Manchhar lake water to be released in Sindh would be determined under the following criteria:
a) the water does not contain more toxics than normally usable, and
b) the proportion of water in Indus and water to be released from the lake be maintained at a ratio of 1:50.
At the Dec 7 meeting of experts, it was said that if the pressure on Manchhar is to be reduced in 15 days, the water intake in Indus from Sukkur Barrage should not exceed 200,000 cusecs – an improbability during the current season.
However, the option of releasing 1,000 cusecs was also discussed but then it needed a discharge from Sukkur Barrage to at least 50,000 cusecs – again a difficult proposition. It was only after experts’ visit to the site and water availability in the Indus that 390 cusecs was released.
At present 15,000 cusecs have been released from the Sukkur Barrage. This includes 30 per cent losses during the 15-day flow to Kotri Barrage.
This year, rains in the Kachho areas have raised the level of lake water. This threatens to inundate adjoining towns and farmlands.
An immediate solution to the exigency is nowhere in sight. In the first instance, the volume of lake effluents released into the Indus cannot exceed the standards recommended by experts. If the lake is allowed to stand the increased pressure, a constant fear of breaches remains. The fate of thousands living in the vicinity is unimaginable.
The only plausible solution is to immediately release 50,000 cusecs of Indus water from the Sukkur Barrage for at least a week and to increase the offtake from Manchhar to 600 cusecs to pre-empt any danger to its banks. In the meantime, the quantum of water to be released from Tarbela for the Indus could be increased to replenish the losses for the current crops.
It is for experts and leaders to fill the shortage caused by the release of water from Tarbela. But to leave things unattended will only invite unforeseen catastrophe.


