DHAKA: It was after floods washed away her family's river-front land in Bangladesh's northern Jamalpur district that Brishti Rafiq's widowed father brought her to live in Dhaka.

"We couldn't survive like that. We had no property or anything," she said of her former home.

She was only three or four years old when they came to the city, but her father soon arranged a job for her, as a maid for another family.

As she grew, Brishti hoped to be a doctor. But like many young girls in Bangladesh, she faced a different future: marriage at 13, in a union arranged by her father.

In this South Asian nation, it is illegal for girls under the age of 18 to marry. But despite government campaigns, many parents do not heed the law.

According to data published in 2015 by UNICEF, the UN children's agency, 29 percent ofBangladeshi girls were married by the time they were 15, the world's highest rate. The figure has since dropped, in part because of efforts to end the practice, but remains at a worrying 18 percent.

Experts, however, fear that growing migration to already overcrowded Dhaka, as climate change pressures exacerbate poverty, could result in a new surge in child marriages.

Early marriage not only deprives girls of education and opportunities but increases their risk of death or severe childbirth injuries if they have babies before their bodies are ready, experts say.

When Brishti was told she would marry, she opposed the match - but her father would not listen.

"He got me married in such a hurry. He didn't ask a lot of questions," said the girl, who is today 14.

"Just like you got a chicken from the market and you have to cook it tonight," she said, matter of factly.

The marriage didn't work out - her husband already had another wife, and Brishti's family couldn't pay the dowry her new inlaws demanded. The couple divorced, and Brishti moved in with her half siblings and an aunt - until a neighbour tried to sexually assault her one night.

Now, divorced and alone at 14, she lives as a lodger in the garment factory where she works each day, one of a growing flood of girls first set adrift by extreme weather and migration, and then trapped by poverty and decisions beyond their control.

Among families who have migrated to Bangladesh's capital from rural areas, often as a result of losing their land or crops to harsh weather, her experience is increasingly common, activists say.

"EVE-TEASING"

The flood of rural families moving to Dhaka's slums is growing as people lose their homes, farms and jobs to river-bank erosion and climate change pressures, such as worsening floods and droughts and more intense storms.

Research carried out among adolescent girls in the southern district of Barguna by the charity Plan International found that, after powerful Cyclone Sidr hit in 2007, a "significant proportion" of schoolgirls migrated to towns to work as maids or in the garment industry.

Most never returned to school - and the number of child marriages surged as well, the report said.

Activists say that, once in crowded cities like Dhaka, girls face an even greater risk of earlymarriage and sexual violence than they would have in their villages back home.

In a 2015 survey by charity ActionAid, 84 percent of girls and women interviewed in sevenBangladeshi cities reported being the subject of verbal abuse and sexual remarks, while 56 percent said they had been subject to sexual harassment in a public place, known in the region as "Eve teasing".

"The Dhaka I grew up in and the Dhaka of today are worlds apart. It was far safer then," said Shahana Siddiqui, a gender specialist at the James P. Grant School of Public Health at Dhaka's BRAC University.

Today, "getting harassed on the streets is just part of women's lives", she said.

Parents fear their daughters are more likely to be exposed to the advances of men in the city, which could tarnish their reputation. Early marriage is seen as one way of dealing with that problem.

"An unmarried girl getting sexually assaulted becomes an issue of family honour," Siddiqui explained. "Instead of saying the boys shouldn't be doing it, the idea is, 'Let's get the girlsmarried off.'"

Brishti's friend Razia Akter, a migrant from Polbandha village, also in Jamalpur, is now under pressure to marry too. Her father, Mohammed Azim, has already given away his eldest daughter in marriage, and thinks it is now time for Razia, 14, to wed as well.

"If my daughter is walking down the road talking to a boy and someone sees, they will tell everyone my daughter is seeing him. Then your honour is immediately lost," he said.

"As soon as people start thinking this has happened, everything is finished, you will lose face."

According to Bangladeshi human rights group Ain o Salish Kendra (ASK), 10 Bangladeshi girlscommitted suicide in 2015 after suffering sexual harassment, and five were murdered when they protested about being harassed, based on information gathered from newspaper reports.

MILLIONS TO MIGRATE

The stresses dragging girls into early marriage could deepen if - as expected - worsening extreme weather, sea-level rise and riverbank erosion drive increasing numbers of people into Bangladesh's already packed slums seeking work, experts warn.

Saleemul Huq, director of the Dhaka-based International Centre for Climate Change and Development, said that in the past 200 years, Bangladesh experienced an average of one major flood every 20 years. But in the past two decades, he said, the frequency has increased to one every five years.

As Bangladesh's dry season gets longer and its rainy season wetter, Huq predicted some 10 million more migrants would head to Bangladesh's cities in the next two decades. Most will likely end up in Dhaka, swelling its already cramped population of around 18 million, he added.

"Dhaka is the fastest-growing megacity in the world," Huq said.

Efforts by the government and aid agencies are underway to help people adapt to climate change where they are living - from providing fresh drinking water in areas where water supplies are contaminated by salt to conserving water for irrigation in drought-prone areas, and introducing hardier crop varieties.

"Unfortunately it is a losing battle," said Huq. "Climate change is always a step ahead of what we can do in order to combat it."

People living in the most hazardous areas bear the brunt of climate-linked disasters, and "they tend to be the poorest people of the community", he added.

"HOPELESS SITUATION"

After Razia's family lost their home to river erosion, her father worked locally as a farm labourer but couldn't support his wife and three children. He brought them to Dhaka three years ago, where they could at least earn enough to eat.

Razia's parents no longer have the money to send her to school. Back home she was a good student, but her dreams of becoming a teacher - something her former schoolteacher encouraged - are out of reach for now, she says.

Razia does not want to marry for another two to three years - and when she does, she hopes to go back to her village. Her mother agrees it would be better to wait until she is 18 to wed.

But her father said the family was "in a hopeless situation", leaving them with little choice. "Can't you understand? We are poor people. We also need to pay for (Razia's) upkeep. So we are forced to get her married," he said.

Siddiqui questions that argument, particularly because Razia has a job as a maid and contributes to the family income.

"Your daughter is earning, so why do you see her as a mouth to feed?" she asks. "Most of the daughters are earning more than the sons."

DISASTER PLANNING

Heather Barr, a women's rights researcher with Human Rights Watch, said that some families she's come across now even arrange early marriages for their daughters in anticipation of their properties being swept away by river erosion.

"One of the ways you cope with it is by trying to unload your kids," she said. "After this cataclysm happens, you're probably not going to be able to feed your daughter, let alone get her married to someone."

Barr said Bangladesh should aim to give women a bigger role in devising ways to adapt to climate change and manage natural disasters, to help ensure girls stay in school and are not forced into early marriage.

"You have to understand the impact on women, and plan for it - and there is really no way to do that except by including women in the process," she said.

Given that the South Asian nation has a female prime minister who has championed women's rights and development, "this is an area where Bangladesh would be perfectly positioned to be a leader", she added.