From start to finish

Please walk us through the chain of events thus far.

It all began in end-July with unexpected and unprecedented rains in the north in Khyber-Pakhtunkhwa, resulting in flash floods that caused immense damage in that province [see accompanying piece, 'Left high and wet']. Water from these floods was then discharged into the Kabul, Jhelum and Chenab rivers, through which it travelled downstream, where this extremely heavy flow caused a breach on the left marginal bund of the Tausa barrage on the Indus in Punjab, causing flooding in areas such as Kot Addu and Muzaffargarh.

Entering Sindh further downstream [see accompanying piece, 'A province devastated'], the first barrage that the body of water encountered was the Guddu, which faced the second-highest discharge in its history. This resulted in a breach of the right bank near Torhi [around 70 km from Sukkur]. Water from this breach flowed into Jacobabad and Shikarpur in Sindh, and Jafferabad in Balochistan.

Water is still flowing through this breach and has inundated more areas. It is expected to go downstream in the form of a 'sheet flow' to the Manchar Lake near Sehwan. The problem, however, is that water from the Manchar Lake drains into a river, and if the level in that river is already high due to the monsoons, water from the flood will inundate surrounding areas instead of draining into the river. The flow is expected to reach Manchar Lake in around a week, and the exact situation will become clear only then. Two days after the first one, another breach occurred – this time on the left marginal bund of the Guddu Barrage. This breach bordered Bhung in Punjab, where agricultural land and a very famous and beautiful mosque were inundated.

Discharge from Sukkur, meanwhile, has reduced, and water is now heading towards the Kotri Barrage near Hyderabad district. While the main Hyderabad city has flood protection bunds, if anything happens and there is a breach we might have problems in the main city as well. The peak discharge – around 700,000 to 800,000 cubic feet of water per second [cusecs] – is expected to reach Kotri barrage on 21 or 22 August. At 6 am on 19 August, the discharge in the area was around 454,000 cusecs and rising. From Kotri, water will flow another 100 miles down to the sea. The Kotri barrage itself is expected to be able to handle the flow, however, and pass it on with no problems because it has a design capacity of 875,000 cusecs.

En route to the sea, water will pass through Thatta district, with the famous Thatta city – home to the historical Makli graveyard, the world's largest burial ground – on its right bank. Until water reaches the sea, the urban population on both sides of this flow will be under threat. The floodwaters will take around 10 or maximum 15 days to reach the sea. One problem, however, is that the full moon is expected around the time the water reaches near the sea. The full moon causes high tides and, in that case, the water will have difficulty entering the sea, and will inundate coastal localities instead.

Would building more dams along the upstream route of the flood have saved these downstream areas of Sindh and Punjab from devastation?

Not really. Building more dams would not have had much of an effect as far as the scale of the disaster is concerned. For one, dams have limited capacities; secondly, they would already have been almost full at this time of the year due to monsoons. Take the Tarbela dam, for instance. It could only have absorbed around 24,000 cusecs. However, an average 400,000 cusecs of water have passed through it during the past weeks.

Many commentators in Pakistan have taken this opportunity to come out vociferously in favour of the much-maligned Kalabagh dam project. Do you agree with their position?

Absolutely not. While the Kalabagh dam might have marginally reduced the scale of the disaster downstream, it would actually have made things even worse for Nowshera district in Khyber-Pakhtunkhwa. It would work similar to the Tarbela example. The dam would have been almost full at this time, and the volume of water that would have passed through it would have been much higher, albeit with a margin of absorption.

When can repair work begin on the barrages and bunds that have been breached or damaged by the floods?

These breaches cannot be closed unless the discharge reduces to 200,000 cusecs. On 19 August, the discharge hovered around one million cusecs. Getting it down to 200,000 cusecs will take at least 15 days – only then can repair work be started.

Will this flood ultimately be able to resolve the sea-erosion problem in the coastal districts of Sindh?

Not in the long run, no. The floodwaters will push the sea back temporarily, but by this time next year, seawater will reclaim the land.

Are historical sites in Sindh in danger from the floodwaters?

Neither of these sites is in any immediate danger. Water was touching Sehwan by 19 August, but even if it gets to Aamri, it will not affect it much. The Sindh archaeological department says that Aamri is just a mound, with nothing in it. Mohenjo-Daro, on the other hand, is well-protected by embankments, etc.

What is your assessment of the National Disaster Management Authority?

It is too early to comment on the work of the NDMA. They can start their work – rescue, relief, then rehabilitation – only after the water recedes. There's not much scope for them to work at the moment.