The Karamana rises in the vicinity of the Agasthiarkoodam about 1600 m above the sea level. The peaks of origin of the river are today known as Chemmunji Motta and Aathiramala and its upper tributary rivers are the Kaaviyaar, Attayaar, Vaiyappadyaar and Thodayaar. The river flows for 66 kilometers in a south - southwest direction before flowing into the Arabian Sea. The largest tributary of the Karamana is the Killiyar, which flows for a distance of 24 kilometres. It has five
anicuts on it which regulates the flow of water. Part of the water was diverted into the Kochar channel which in turn fed the Pathrakulam pond (no longer exists) adjacent to current Padmatheerthakulam outside the
Padmanabhaswamy Temple. There are several temples located along the Killiyar's banks, the most famous of which is the Attukal Temple. The Killiyar drains the
Nedumangad forest and its basin is rich in avian fauna.Killiyar merges with Karamana river at Pallathukadavu near Thiruvallam.Karamana river merges with the Arabian Sea through the Pozhikkara
estuary. In its final lap, the river runs parallel to the sea and the river here is known as the Edayar. == Dams ==