HYDERABAD, Aug 27 Having inundated Qambar-Shahdadkot district, the raging floodwaters unleashed by a breach in Torhi embankment are now headed towards Manchhar lake through MNVD, ringing alarm bells in Khairpur Nathan Shah, Johi, Mehar, Dadu and Sehwan towns.

The floodwaters will hit the towns in case of possible breaches in the MNVD (Main Nara Valley Drain) before flowing to the lake.

The drain, which has a designed discharge capacity of 3,500 cusecs, started disposing of 5,100 cusecs including effluent into Hamal lake from Friday.

Dadu DCO Iqbal Memon told a private TV channel on Friday that population of 391 villages in 18 union councils of Khairpur Nathan Shah, Mehar and Johi had been asked to evacuate because floodwaters from Qambar-Shahdadkot would enter Dadu anytime that day in the evening.

But before any harm came to the lake, the MNVD might itself fall prey to gushing floodwaters because of its weak embankments. In that case areas of Dadu district, including Johi, Khairpur Nathan Shah, Dadu and Mehar talukas will be flooded before the floodwaters drop into Manchhar.

No figures are available for quantum of floodwater from Shahdadkot, which has entered Hamal lake from where it will be disposed of into the MNVD. The lake's level as on Friday was 111.8RL and it can withstand pressure of up to 116RL.

The lake water is released into the Indus when its level reaches alarming proportions but irrigation authorities are more worried by continuous rise in Indus at Kotri barrage. Its upstream flow was 964,897 cusecs and downstream 939,442 cusecs by 6pm.

There has been no change in upstream flow, 964,897 cusecs, since 12am but officials hope its level may start receding after Friday midnight.

Manchhar lake's water is disposed of into the Indus through Aral Wah which has 119.35RL head regulator gauge and 119.1RL tail regulator, the point where lake water is released into the river.

Officials believe that flows from Shahdadkot will take six to seven days to reach the lake through Hamal and then MNVD which has a designed capacity of 3,500 cusecs.

“It's normal flow of effluent varies between 1,200 to 2,200 cusecs and 5,100 cusecs is an abnormal flow in the MNVD,” said executive engineer Manchhar Lake, Zahid Shaikh.

Water technologist Dr. Siddiqui said that irrigation officials started feeling worried when the lake's level touched 116RL and he himself was perturbed how the lake would be emptied into the Indus. “The situation is too grim because it poses a serious threat to big populations of Jamshoro and Dadu districts,” he said.

The fishermen community numbering 20,000 to 25,000 will be worst sufferers in case of breaches in Manchhar's bunds. Their abodes dot the lake's fringes and several other villages are located in the adjoining areas.

Besides, entire Sehwan taluka faces a potential threat of floods. Sindh finance minister Murad Ali Shah whose constituency includes the town says the “problem is serious”.

He said that entire machinery had been moved to Manchhar lake to ward off any threat. “We believe that by the time the lake gets filled the Indus will be showing declining trend and it will be easy for us to release lake water,” he said.

A drop in water level at Dadu-Moro bypass is taken as a declining trend for water level at Kotri upstream. Officials say that water level at Dadu-Moro bypass should not be beyond 127RL to enable them to release lake water into the Indus.

Pakistan Fisherfolk Forum's chief Mohammad Ali Shah agreed to the view that the present situation posed a serious risk to the lake. “Our community will be suffering huge economic losses in case of breaches in the lake,” he said. Entire Bubak town would be inundated in case of breaches, he said.

According to an irrigation official if 15,000 cusecs of water enters the lake daily it will increase lake's level by three feet in 12 days. “By that time we hope Indus level will start dropping and we will feel comfortable to release water into Indus. It's a hope against hope. But we must hope for the better,” he said.