– Young Filmmaker award, Bangkok Critics Assembly – Special Mention Award, Locarno International Film Festival In 2013, after Numbenchapol's debut documentary feature Boundary (ฟ้าต่ำแผ่นดินสูง) that examines the border dispute between Thailand and Cambodia was premiered at 63rd Berlin International Film Festival, it had been banned by Thai ministry of culture as "a treat to national security and international relations"[1] despite the fact that rating system has been enforced under the Motion Pictures and Video Act B.E.
[3] Boundary was later rated 18+ and was self-distributed by the director at limited cinemas in Chiang Mai, Khon Kaen, Udon Thani and Bangkok respectively, from June 27 – July 21, 2013.
[4] Boundary was inspired in part by Numbenchapol's desire to learn the truth behind the 2010 Thai political protests.
Numbenchapol's second documentary feature By the River (สายน้ำติดเชื้อ) premiered at the 66th Locarno International Film Festival and received Special Mention Award in August 2013.
The film deals with another controversial issue in Thailand: the 15-year-suffering of Karen villagers from the lead contaminated river at Lower Klity in Kanchanaburi province.