The spread of makeshift aluminum shelters erected by Syrians now outpaces new rows of U.N. canvas tents here in chilly northern Jordan, home to one of the world’s fastest-growing refugee camps. A vast black-market bazaar has sprouted from the desert sand, where enterprising refugees hawk bottled water and other basic necessities that most fellow camp residents can’t afford.

As a mass Syrian emigration spills into neighboring countries, relief organizations acknowledge that they can hardly keep up. The exodus is accelerating so quickly that the tally of need will almost certainly hit a grim milestone this week, when the number of Syrian refugees who have registered with the United Nations — or are on months-long waiting lists to do so — is expected to hit 1 million.

One-third of those desperate migrants have fled since January, the United Nations says, most into Jordan, Lebanon and Turkey. Here in northern Jordan, the Zaatari camp has exploded from a modest cluster of 500 tents in August to a refugee metropolis with a population of more than 146,000 — larger than the nearby city of Mafraq and well more than double the camp’s 60,000-person capacity.

Yet aid officials say Syrians fleeing alleged massacres and Damascus’s fresh bombing campaigns are stepping into a growing humanitarian catastrophe, either in overcrowded camps with little to offer or, even more frequently, in urban areas that struggle to support them and where the welcome has worn thin.

The crisis is compounded by a growing funding gap, which U.N. agencies say is forcing cutbacks on basic supplies and shelter.

Although the international community pledged to meet a $1.5 billion U.N. appeal in December for aid to Syrian refugees, the U.N. refu­gee agency says it has yet to receive 20 percent of the promised money. In any case, the requested assistance was set to cover the needs of what was then a regional growth of about 1,500 new refugees per day — a mere quarter of the average number now entering neighboring countries daily.

“We are facing rising needs, dwindling resources and rising numbers at the border each day,” said Andrew Harper, the representative for the U.N. High Commissioner for Refugees in Jordan. “This is nothing short of a perfect storm.”

With just 9 percent of its $57 million budget met, the U.N. children’s agency in Jordan is set to scale back sanitation services and education programs, while the World Food Program has reduced daily food rations in Zaatari nearly by half.

U.N. agencies say they may soon be forced to stop distributing tents, blankets and hygienic supplies. Planned camps in Jordan and other countries are likely to lack essentials such as purified drinking water and gravel to prevent water from seeping through tent floors, officials said.

In Zaatari, the resource crunch has sparked fierce competition among refugees. On a recent day, those awarded bread at the camp’s distribution center had lined up in front of the warehouse as early as 4 a.m.

Meanwhile, men in worn sweatshirts and flowing Bedouin cotton robes embarked on what has become known as the “march of shame” to the camp’s mile-long black-market souk after being turned away empty-handed at the bread line.

Mohammed Al Kayyed, 42, and his son were among those headed to the claustrophobic row of aluminum stands, where several camp residents said they spend an average of $15 a day to feed their families.

As the civil war in Syria continues, refugees are streaming into Turkey. The Post’s Jenna Johnson just returned from the region and describes what she saw. (The Fold/The Washington Post)

“Most days there is no bread, there are never any vegetables, and all we get is a half-bag of lentils and barely any respect,” the former engineer said of official aid handouts. “You have to be rich to live like a refugee.”

‘Sell or starve’

In the market, entrepreneurial Syrians sell everything from mismatched shoes to satellite receivers smuggled in by Jordanian business partners, turning profits as high as $300 per day. Camp officials, knowing residents have little choice, turn a blind eye to the shadowy commerce.

“Here in Zaatari, it is either sell or starve,” said a 45-year-old cigarette vendor who gave only his nickname, Abu Kamal Al Dimashqi.

Overcrowding and a dwindling number of tents have given rise to a predatory real estate market, with established refugees renting plots of land, hand-built shelters and residential trailers to new arrivals for $150 to $300 a month.

“We Syrians should be helping each other, opening our homes to each other,” said 78-year-old Ahmed Al Rifai, who was perched on the edge of a stack of mattresses as he waited for a hired team of Syrians to assemble a tent he purchased for $50 a few hours earlier. “Now even our own people have turned their backs on us.”

Competition over space and food is taking a dark turn, fueling a rise in theft and sometimes violent crime, refugees said. Blankets, food, water tanks and cinder blocks vanish if left unattended. On Sunday, one of several self-appointed refu­gee watch committees apprehended three men who were allegedly planning to set fire to the tent of a business rival, said Abu Omar Al Darawi, a seven-month camp resident who heads a committee.

“I woke up last week to find my entire door was gone,” said Osama al Sour, 30, knocking on the replacement door of his trailer.

Even as it surges, relief officials say the refugee crisis is nowhere near ending. In Jordan, the government says the number of refugees is on pace to swell from the current 400,000 to more than 1 million by the end of the year. Accommodating that population would require the construction of a new camp every 30 days.

“Every time we think we have received the last of the night’s crossings, we get calls that thousands more are on the way,” Jordanian Brig. Gen. Hussein Zayoud said, watching as his soldiers helped hundreds of Syrian women and children over the collapsed wire fence separating the two countries on a recent night when about 6,000 Syrians entered Jordan. “It has become a 24-hour cycle.”

‘A second population’

Jordan has pledged to keep its borders open and establish a string of desert camps, but the government says plans have been frozen because of the same funding woes hitting relief agencies. The direct cost of caring for the refugee community is set to reach $1 billion this year, the government says — the equivalent of half of Jordan’s budget deficit.

Meanwhile, the hundreds of thousands of Syrians living in cities and towns outside the camps are driving up housing prices and sparking water shortages in one of the world’s water-poorest countries. Thirty thousand Syrian students are pushing overcrowded schools onto reduced, two-shift systems.

“Jordan can barely afford to provide water, education and electricity for its own population, and now we have a second population growing by 1 percent each day,” said Samih al-Maaytah, a Jordanian government spokesman. “No country on Earth could balance those challenges.”

But Jordan and other countries will probably have to.

“Even with the thousands that have already crossed” said Davide Terzi, the Jordan chief of mission for the International Organization for Migration, “there are millions more who may be the real crisis to come.”