Pakistan's biggest floods in 80 years threaten to inflict widespread suffering in Sindh province after the unpopular government failed millions of people ravaged by the disaster in other parts of the country.
Raging waters have spread from the northwest to the Punjab agricultural heartland and then down to the southern province of Sindh, as Pakistanis watched villages collapse, thousands of people drown, and their president leave for state visits abroad at the height of the disaster. Officials in Sindh, home to Pakistan's biggest city and commercial hub Karachi, are scrambling to prevent heavy loss of life and more destruction to the mainstay agriculture industry.
Meteorologist Hazrat Mir said flood waters were moving swiftly in north Sindh province and would enter the town of Sukkur by Saturday.
So far, the floods have killed more than 1,600 people and officials said the toll was likely to climb. More than 4 million have also lost their livelihoods and homes.
"What we see is a sea of people in need," said Manuel Bessler, head of the Pakistan office of the U.N. Office for the Coordination of Humanitarian Affairs (OCHA).
"It is an evolving emergency. We are afraid it will get worse before it gets better," he added. Pakistan's seasonal monsoon rains normally continue through the month of August.
The government's lacklustre response has reinforced the view among Pakistanis that civilian administrations, perceived as corrupt and weak, are unable to handle big crises, leaving the army to step in. The military has ruled Pakistan for more than half of its turbulent history.
"There is nothing but just water all around us," said a Reuters cameraman who travelled for several miles by boat with army troops just southeast of the town of Sukkur.
Children, their homes swept away, helped parents to set up temporarily shelters of clothes and plastic sheeting on a roadside in Sukkar, bunkering down to wait for rescue, or aid. Elderly villagers puffed on traditional water pipes in an attempt to regain some normalcy.
"I've lost my house, food. We have nothing. Nobody has come to us," said villager Ali Nawaz. About 350,000 people have been evacuated from low-lying areas of the Indus river basin in Sindh.
CASH CROPS AT RISK
President Asif Ali Zardari, already squeezed by a Taliban insurgency, chronic power cuts and many other critical issues, is on the political defensive once again after his decision to travel abroad during the catastrophe drew fierce criticism.
The United States wants Zardari's government to bring political and economic stability to Pakistan, an ally it believes can help ease a Taliban insurgency in Afghanistan, where an American troop pullout starts next summer.
Unable to rely on authorities, Pakistanis must innovate to survive, using makeshift, hand-operated pulleys to move people on wooden planks above rivers where waters brought down bridges.
Others simply don't have the energy.
In Sanawa village in Punjab, a Pakistani soldier carried an elderly man to a helicopter. A big crowd waited around a nearby mosque, some waist-deep in muddy water, hoping for relief.
Authorities in Sindh said treacherous conditions were hampering evacuation efforts, but added that villagers were reluctant to leave their homes.
Determining the overall costs of the floods may not be possible until authorities survey vast areas where raging waters have swallowed up entire villages.
In a country that heavily relies on foreign aid, this disaster is likely to have a crippling effect on the the economy.
At least 1.3 million acres of crops have been destroyed in the Punjab agricultural heartland alone, relief officials said.
Huge agriculture losses would mean Pakistan will have to spend more to import cotton for its crucial textile industry, as well as sugar, and will have less rice to export.
"The body of water going south is affecting a large area that is highly-densely populated. It is the food basket of Pakistan, so it will have long-term effects," said Oscar Butragueno of the United Nation's Children's Fund (UNICEF).