Angammedilla National Park is one of the new national parks in Sri Lanka. The region was designated national park on 6 June 2006. Originally Angammedilla was a forest reserve within the Minneriya-Girithale Sanctuary declared on 12 February 1988. The park is declared mainly to protect the drainage basin of Parakrama Samudra. Angammedilla also secures the drainage basins of Minneriya and Girithale irrigation tanks, water sources in Sudu Kanda (Sinhala for "White hill") and habitats and wildlife of the adjacent forests. It is located 225 kilometres (140 mi) away from Colombo in Polonnaruwa District
Amban river which is sourced by Sudu Kanda forms the southern border of the park. A mountain range stretches across the park from Girithale to Minneriya. In the drought period the park is very dry. In the rainy season, mountainous area receives more rainfall than the plains. Since a mix wet and dry climate persists in the park the vegetation is a mix of wet zone and dry zone plants.
In the ancient times water has irrigated from Amban river to Parakrama Samudra in a canal done in stone. The rocky wall of the canal called royal wall by the villagers