Cambodian-American film-maker Kalyanee Mam has walked away with the 2013 Sundance Film Festival’s Grand Jury Prize for World Cinema for her directorial debut A River Changes Course.

The documentary delves into the environmental and social effects of mass development in the country. It beat 12 other films to win the  prestigious award.

Mam, who left Cambodia in 1979, said she was “completely shocked” to win  and was “jumping up and down on the stage” at the Utah festival on Saturday night.

“I ran up to the podium with no speech prepared... It was a great opportunity to talk about the meaning of the film.”

A River Changes Course was produced by the Documentation Center of Cambodia and vividly documents the lives of three subjects: Sav Samourn, an ethnic Jarai minority from Ratanakkiri; teenage fisherman Sari Math; and Khieu Mok, who left the fields of Svay Rieng for the capital’s garment factory to provide for her family of eight.

Mam says, however, the most meaningful moment for her was the local screening at DC-CAM in Phnom Penh in October last year,.

“There were about 600 people in the audience: the subjects, families and communities were there... it was very special. They were quite shocked, but absorbed and engaged. One Cham woman said for the first time in her life she felt she belonged to Cambodia.”

The lawyer turned film-maker said her dreams were for the film to screen in other countries facing similar issues, but most importantly to have those in far-flung areas in Cambodia see the film.

“They need to see they are citizens who are capable of changing their political, social and environmental landscape. Right now the majority don’t have access to media so they don’t realise what is happening to them is happening all around the country.”

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