Ambon, Ulan, Baha is an original contemporary sarswela - a form of Kambayoka play - that includes singing and dancing. The plot is about the bad effects of continuous cutting of trees in the forest.
Rivera received his AB English-Filipino degree from the University of the Philippines. He lead the movement for the theater when he established the Sining Kambayoka, a folk theater company on the campus of Mindanao State University in the 1970s.
He has won several awards, including the 8th Annual Gawad Ustetika Awards in the Play category, 1997 Patnubay ng Sining at Kalinangan para sa Tanghalan from the City of Manila and the 2002 National Book Award from the Manila Critics' Circle for his book, Mga Dula sa Magkakaibang Midyum.
He started out in Severino Montano's Arena Theatre Guild and Cecile Guidote’s PETA. He represented the Philippines in numerous International Theater Festivals and Conferences in the US, Korea, Thailand, Mexico, Singapore and Australia.