KARACHI, Pakistan — Floodwaters that have devastated Pakistan for five weeks headed to the Arabian Sea on Tuesday after swallowing two final towns, but the challenges of delivering emergency aid to 8 million people remained.
The floods have moved down from the mountainous northwest, submerging or affecting almost one-fifth of the country at their peak. Waters have begun to recede in the north and in the eastern province of Punjab, but they have been submerging towns in southern Sindh province close to the Indus River over the last 10 days.
The scale of the disaster has raised concerns about the stability of nuclear-armed Pakistan, which is already reeling from al-Qaida and Taliban violence and massive economic woes.
Foreign countries have pledged hundreds of millions of dollars to help Pakistan respond to the floods. Even the country's archenemy, India, has offered assistance and announced Tuesday that it was increasing its aid from $5 million to $25 million.
The last two towns in the path of the floods were hit late Monday, said disaster management official Hadi Bakhsh.
"The floodwaters hit Khahre Jamali and Jati towns last night, and now there is no other village or town in the way of the deluge," he said, adding that people had already fled the towns, parts of which were under 10 feet (3 meters) of water.
"The floodwaters are now heading to the Arabian Sea," he said.
Authorities have struggled to feed, house and arrange medical care for the survivors of the floods. Foreign donors and the United Nations were slow to respond to the disaster, in part because it took a long time for its extent to become clear.
Aid is slowly reaching the worst-affected areas by army helicopter, road and boat, but millions have received little or no help. The U.N. warned that additional funding for emergency food was urgently needed to ensure supplies into next month.
Authorities have also struggled to cope with a growing number of cases of severe diarrhea and malaria caused by dirty water that offers a perfect breeding ground for insects and disease. More than 500,000 cases of acute diarrhea and nearly 95,000 cases of suspected malaria have been treated since the floods first hit, the U.N.'s World Health Organization said Tuesday.
Once all the floodwaters recede, the country will be left with a massive relief and reconstruction effort that will cost billions of dollars and take years. An estimated 1 million homes have been damaged or destroyed, five times as many as were hit by this year's earthquake in Haiti.