Bharathappuzha, also known as the River Nila, is a river in India in the state of Kerala. With a length of 209 km, it is the second-longest river in Kerala, after the Periyar River. The word "Nila" indicates the culture more than just a river. Nila has groomed the culture and life of south Malabar part of Kerala. We see the name "Peraar" indicating the same river in ancient scripts and documents.
The headwaters of the main tributary of Bharathappuzha originates in the Anaimalai Hills in the Western Ghats, and flows westward through Palakkad Gap, across Palakkad, Thrissur and Malappuram districts of Kerala, with many tributaries joining it, including the Tirur River. For the first 40 km or so, the Bharathappuzha follows an almost northerly course till Pollachi near Coimbatore. At Parli, the Kannadipuzha and Kalpathippuza merge and flow as Bharathappuzha, following a westerly course until it empties into the Arabian Sea at Ponnani. The Thootha River merges with the Nila at Pallippuram. As the Thootha River is rich in water, after its merger, the Nila becomes thicker in flow.