After five years of devastating drought, a month of heavy rains holds the promise of salvation for hundreds of thousands of refugees, nomads and isolated villagers here in western Sudan. Land that had turned to desert is green with crops. The ponds have frogs.

But even the earliest harvests are still weeks away. And as floods, mires and washed-out bridges have brought massive international relief efforts to a crawl, many areas have no food.

"If the food doesn't come in now, it's this one month that will kill them all," said Ekber Menemencioglu, who represents the Office of the United Nations High Commissioner for Refugees here. "In those areas that didn't have seeds, or ate them before the planting, they also will die."

The problem is no longer a lack of food in the country. More than 250,000 tons of grain have arrived at Port Sudan on the Red Sea. The problem is getting it here.

A washed-out bridge west of the Nile River town of Kosti cut off Kordofan and Darfur provinces from supply by rail 10 days ago. In Washington, an Agency of International Development official said that traffic had been diverted around the washout and that food again was moving by rail.

Almost 200 railroad cars have been stranded along the line by other, smaller breaks in the track.

The villages in the vicinity of this garrison town are the most direly affected. People there are said to get an average of only 37 percent of the food they need. At one settlement, called Beida, the police chief sent an emergency message last week in which he begged for food and for shrouds to bury as many as 15 bodies a day.

This region "slap-bang in the center of the African continent," as one relief worker described it, is as close to the port of Douala, Cameroon, on the Atlantic as to Port Sudan in the east. Supply convoys have started toward it from both directions, but both are more than 1,000 miles away by road.

Some truck convoys have been able to reach El Fasher and Nyala, the other major towns of Darfur. But the Geneina area seems to be checkmated by disasters.

The wadis, or riverbeds, around the town have turned it into an island. The one road bridge leading north washed out on the night of July 8. The southern road from Zalingei is cut in at least three places by flooded wadis.

Flights of C130s from Khartoum now arrive daily and by later this week, when five American planes are to be added to the five already supplied by the European Community, something like an "air bridge" is supposed to start operating. But the Geneina runway is disintegrating already. The asphalt has peeled away like burned skin, and light planes no longer dare land on its ragged surface.

The Asserni refugee camp nearby, with almost 20,000 Chadians and displaced Sudanese,received no food shipment for 25 days. Many wandered back to the desert to try to survive, grubbing through anthills for the insects' stores of grain, eating berries from the mokhet plant that have to be boiled for days before the poison is out of them.

"The only reason we're not getting as many deaths as predicted is that we are dealing with a nomadic people who know survival techniques -- thank God," said Menemencioglu, the son of a Turkish diplomat and a graduate of American University in Washington. "What we are doing is making a supplement to survival techniques."

Some food was on hand for children in intensive and supplementary feeding programs at Asserni. On Tuesday, food flown in from Khartoum was trucked for an hour and a half across the desert, then rowed across the flooded wadi in a rubber raft and distributed. But on Wednesday, hundreds of children appeared still to be in terrible condition.

At an intensive feeding center they were carried in by their mothers or by siblings barely bigger than they were and almost as thin. Some screamed, no longer able to eat. Others stared in blank fright at everything around them. Some were limp, their eyes rolled back in their heads.

The British voluntary organization Oxfam, which is supervising the nutrition program, estimates that 20 percent of the children in Asserni weigh only 70 percent of what they should and says the likelihood is that without constant attention they will die. As many as half the children weigh only 80 percent of that indicated for their height.

"One plane load feeds this camp for one day," said Ann Dalrymple-Smith, an Oxfam nurse. Outside the camp, she noted, there are a million people in this region who need to be fed and are getting nothing.

In Khartoum, there is already a great deal of talk about what mistakes were made in planning this relief effort. It was known more than a year ago that there would be a crisis here and that if food was not stockpiled before the rains began the crisis would be a disaster.

The U.S. Agency for International Development has been sharply criticized by some relief workers for relying too much on an American-Sudanese trucking firm and on the country's railroads.

But virtually every institution in Sudan is operating on the verge of collapse as a result of the country's insolvency, its long history of corruption and its recent political upheavals. There appears to be increasing recognition that it is no easier to assign blame for failure here than it is to find solutions.

"U.S. AID has come in for a fair amount of criticism," said Chris Eldridge, Darfur field director for Britain's Save the Children Fund in Nyala, "but they're the only organization that's really done anything so far." More than 80 percent of the food assistance to Sudan has come from AID, according to the government.

While the situation in the west has steadily deteriorated, that in the east near the Ethiopian border has improved considerably, according to U.N. officials. Although Wad Kowli and other camps there have been cut off by the rains as well, they were able to stockpile enough food early on to sustain them.

A measure of how difficult the situation is here, however, is just how little is known about it. The region affected by drought is as big as Spain but has only one paved road.

"We just don't know where people have moved to or where they moved from. We don't know how many people are dying out there," said Eldridge. "Facts are as rare as paved roads."

Yet while relief workers say there was a sense of desperation a month ago, frantic scrambling and improvisation by all the agencies concerned are beginning to bring some results.

Two helicopters supplied by AID to the European Community's air bridge are expected shortly to fly food to villages such as Beida and to reconnoiter the region to find where people have congregated.

There are also plans to fly in materiel to repair the bridge and runway. Meanwhile, a fleet of desert trucks is being assembled from around the region to replace the market trucks that were being requisitioned before -- and that soon proved useless on the ruts and mires that pass for roads.

A representative of the San Francisco-based Live Aid foundation, which sponsored a musical appeal for funds last weekend, is reported to have found 140 trucks that may be serviceable.

Local AID director William R. Brown said, "We've got a guy in Italy talking to a German who claims he's got 200 desert trucks in Turkey."

Slowly the rail line is being pieced back together. "Not much else can go wrong," said Eldridge. Then he stopped himself: "I hesitate to say that because something else probably will go wrong."