The world’s largest refugee camp, a temporary home to more than half a million people that sprawls precariously across barren hills in southeastern Bangladesh, faces a looming disaster as early as April when the first storms of the monsoon season hit, aid workers warn.

“It’s going to be landslides, flash floods, inundation,” said Tommy Thompson, chief of emergency support and response for the World Food Program. “It’s going to be a very, very challenging wet season. That’s if we don’t have a cyclone.”

Nearly 600,000 Rohingya Muslim refugees live in the camp, at Cox’s Bazar, near the southern tip of Bangladesh. Cyclones, which can occur from March to July, would considerably worsen the situation beyond the dangers of flooding and landslides.

The Rohingya camp — known officially as the Kutupalong-Balukhali settlements, and informally as the megacamp — is the most urgent example of the new calamities that come with the global refugee crisis: a huge influx of desperate people fleeing war or persecution, only to face natural disaster in an ecologically fragile area potentially made more precarious by climate change.

“We can definitely see how this is going to be a catastrophe, no matter what,” said Mélody Braun, who studies risk reduction strategies at the International Research Institute for Climate and Society at Columbia University and is visiting the camp this week. “There’s really no space. People are everywhere. Slopes are really high.”

Before the Rohingya started crossing into Bangladesh from Myanmar in large numbers in the summer, fleeing attacks on their villages by the army and allied mobs, the hills were dotted with forest.

But then, in a matter of weeks, as refugees poured in by the tens of thousands, trees were hacked away. Canals were dug. Bamboo-and-tarp shacks went up. More trees were cut as refugees scrambled to find firewood.

The hills, where elephants recently roamed, are now bare. Even the roots have been pulled out, leaving nothing to hold the parched soil together as rainwater washes downhill, potentially taking tents and people with it and quickly inundating low-lying settlements. The United Nations says 100,000 refugees are at acute risk from landslides and floods.

The early rains — known in Bengali as kalboishakhi, which translates loosely as the storms of an “evil summer” — are a precursor to the full-on monsoons. They strike when the soil is still dry and especially susceptible to mudslides. The only warning of their approach is usually hot winds that send the dry earth of summer swirling through the air.

“You have whirlwinds of dust,” said Iffat Nawaz, a spokeswoman for BRAC, an international relief agency that is based in Bangladesh. “Suddenly it gets dark in middle of the day and it pours. We usually welcome that. It’s cooling. This year in the middle of the refugee crisis, it’s not something to look forward to.”

Southeastern Bangladesh is already one of the wettest parts of a wet country, with 12 feet of rain on average every year. A warming atmosphere can hold more moisture and unleash more intense downpours, and make wet places even wetter. That may already be happening in and around Cox’s Bazar. Total pre-monsoon rainfall in the region has increased by about one inch every five years over the past five decades, a 2014 study by researchers from Bangladesh University of Engineering and Technology found.

When the rains come, latrines are likely to overflow, bringing the risk of cholera and other waterborne diseases.

In February, U.N. agencies began dispatching engineering crews to clear blocked sewage canals at risk of overflowing in the rainy season. They distributed compressed rice husk, an alternative to firewood, but that met only a small fraction of the refugees’ needs. The government has yet to allow the U.N. refugee agency to distribute gas stoves that would decrease the demand for firewood.

Bangladesh, one of the poorest, most densely populated countries in the world, opened its borders to the Rohingya in August, when they began arriving with tales of massacres by the Myanmar military. They crossed a swollen river to get to safety, walking through muddy fields and sleeping under the open sky with their children. The Bangladeshi government let them settle around an area where there was already a relatively small Rohingya refugee camp.

A spokeswoman for the International Organization for Migration, which manages the camp, said aid agencies were well aware of the natural disaster risks, but that they struggled in the early months to provide basic services and focused on immediate needs: water, food and shelter.

Bangladeshi and U.N. officials say they are preparing land elsewhere to relocate roughly 100,000 refugees from the megacamp. In one instance, the United Nations is leveling a hilly area allocated by the government to relocate refugees. And officials are distributing more tarps, bamboo and sandbags to refugees to shore up their tents before the rains begin.

Could any of this have been prevented? Thompson said it would have helped to set up a camp on flatter land and to prevent the clear-cutting of the forest.

“We will be looking at decisions that were taken in the first six months of this operation,” he said by phone from Cox’s Bazar. “We always learn from our previous experiences and get better. Having said that, we find ourselves in circumstances we couldn’t have imagined.”

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