The U.N. estimates that just under 500,000 registered refugees have crossed the border into Lebanon since the Syrian conflict started in March 2011. Individuals and families fleeing Syria are now scattered across the country, but the largest number of refugees is concentrated in the Bekaa Valley. Those who can afford rent live in rooms or houses, while the most impoverished occupy ad hoc settlements that have sprung up in and around northern towns such as Arsal.

According to UNHCR, 78 percent of Syrian refugees in Lebanon are women and children. This gender disparity is at least partially due to the high number of male casualties resulting from the conflict. In addition, many men have elected to continue fighting in Syria instead of fleeing to Lebanon and other neighboring countries. These circumstances ensure that the majority of Syrian refugees are also the most vulnerable. Reports of sexual harassment and assault of women and girls, sometimes by other Syrians, but mostly at the hands of local men, have dogged settlements in Lebanon, Jordan, and Egypt for some time.

Jihane Larous, UNICEF's child protection and gender-based violence specialist, says the threat of sexual violence, combined with extreme poverty, has caused an upswing in the number of child marriages among Syrian refugees.

"With the emergency surrounding the conflict in Syria, the trend of early marriage has increased," says Larous. "At the same time, the reasons for early marriage have changed. In addition to the economic motivation behind this practice...there is also the issue of protection...to protect the honor of the girl and her family. Because of the prevalence of sexual violence, whether in Syria or here in Lebanon, marrying your daughter puts her under the protection of a man, so she'll be less at risk of being assaulted."

In a much smaller, shabbier room at a settlement near a mosque in Arsal, another 12 women sit on mattresses lining the floor. Their clothes are torn and ragged, their faces tired. A few hold babies in their laps. The mother of three of the girls, a middle-aged woman named Rihab, holds court at the center of the room.

"The girls can't leave and go anywhere by themselves," she says. "The men harass them and grope them. Honestly, I have two girls who aren't married yet. If men came along and wanted to marry them, I would agree right away, so I can save them...from the danger and harassment."

A 20-year-old woman named Reem holds a squirming three-year-old girl in her lap as she talks.

"A girl we know was kidnapped by four men," she says. "They kept her for 10 days, then threw her in the street. Imagine how traumatized she must be. 10 days, and God forbid, four men."

One of Rihab's daughters, a pretty 17-year-old named Sarab, chimes in. "Now her father wants to marry her to anyone, even a beggar," she says, shaking her head.