Asad Ali Fadla was sitting down to dinner with his family when a wall of water swept down his street and smashed into his compound in Sennar town on the banks of the Blue Nile in southeastern Sudan.

Minutes after he had rushed out to check the damage, the flash flood started tearing away at the bricks of the outer wall. Just over an hour later, more than half his home had been reduced to a mass of surging mud and rubble.

"If we hadn't got out in time, we could have died when the roof collapsed," said Asad, who has spent the last week filling the biggest holes in his wall.

"I am going to leave most of the repair work until after the rainy season," added the 25-year-old. "It will rain again soon and more floods will come."

Asad, his parents, five brothers and sisters, are among thousands whose homes have been swept away as heavy rains sparked flash floods across Sudan over the past week.

State news agency SUNA on Sunday quoted the council of ministers spokesman Omer Mohammed Salih as saying more than 4,000 homes had been destroyed throughout Sudan.

"Many areas in the country witnessed high levels of rains and that high levels of rains and floods are still expected in the coming weeks," he told SUNA.

The floods caused huge damage and left countless stagnant pools in their wake -- each of them a potential breeding ground for malaria and water-borne diseases.

All the more frustrating, many Sennar residents told Reuters, because the disaster had been totally predictable and preventable.

Critics blame officials for a lack of preparation, central government planning and local government implementation.

"These rains happen every year. They are seasonal," said one Sennar resident who asked not to be named. "But the planning by the authorities has been very bad."

Residents said drains and dykes had been poorly maintained since the last rains. Ditches along the main roads were left to clog up with mud and rubble.

The Sennar resident said the main road was built too high so it trapped the rain water and stopped it flowing into the Blue Nile river. Instead it flowed into residential areas.

Tens of thousands homeless

The Sudanese Red Crescent last week said more than 500 households had suffered the same fate in Rabak, around 100 kilometers (60 miles) from Sennar.

Red Crescent staff had also received reports of similar inundations in Kassala, North Kordofan and Jazeera State.

Flood waters from heavy rains and swollen rivers have spread across these plains for as long as anyone can remember.

Most years, the farmers in Sudan's agricultural heartland welcome and manage the flow to irrigate their fields. Other industries have learned to adapt.

But record rains last year overwhelmed local dykes and left tens of thousands of people homeless.

"Every year there is a potential for disaster," George Were, British aid agency Oxfam's project coordinator for east Sudan, told Reuters.

"You get winds of near gale power and heavy rainfall ... but it is something that can be predicted."

"But at the moment, there is no time to take the appropriate action before the flood comes knocking at the door. Last year it swept away whole villages of migrant workers around Tokar."

That area is still recovering from the effects of a decade-long insurgency which ended last year when Eastern Front rebels signed a peace deal with government forces.

"The dykes are not very well maintained because of the war and other factors," said another aid worker who asked not to be named.

Back in Sennar thunder and lightening struck and the rain started falling again. Most of the dirt roads were still blocked with pools of water, each visibly teeming with mosquito larvae.