The Penna river basin lies in the rain shadow region of Eastern Ghats and receives 500 mm average rainfall annually.
The name Pinakini refers to Pinaka, the bow of Nandhiswara, the presiding deity of the Nandi hills at the origin of the river.
The main stream starts in Nandi Hills in of Karnataka, flowing for 597 km to the north and east through several mountains and plains, draining into the Bay of Bengal in Nellore district of Andhra Pradesh.
The major tributaries of the Penna are the Jayamangali, Kunderu and Sagileru from the north, and Chitravathi, Papagni and Cheyyeru from the south.
The Penna gains the volume but loses stream by the time it crosses Palakondalu and enters Kadapa district of Andhra Pradesh.
It regains the stream in district after meeting many tributaries including Chitravati, Bahuda, Papagni, Kunderu, Sagileru and Cheyyeru and flows near the towns like Kodur, Jammalamadugu, Proddatur, Kamalapuram and Siddhavattam.
The Penna river forces through Gandikota gorge and flows east through a gap in the Eastern Ghats to go to the plains of Coastal Andhra.
The Papagni river rises near Sidlaghatta town in Kolar district of Karnataka and traverses 205 km before joining the Penna on the right bank.
The Kunderu river rises in Kurnool district of Andhra Pradesh and travels 205 km before joining the Penna on the left bank.
The Penna emerges from Velikonda Range in Eastern Ghats at 467 km from its source and enters the plains under Somasila Dam in the Nellore district.
The Biraperu is a small stream which carries rainfall of the north east portion of Nellore, Udayagiri and Kavali Mandals to the Penna river.
The Penna basin lies in the rain shadow of the high Western Ghats ranges, which prevents much moisture from reaching the region.
The Penna basin suffered from a prolonged drought in the 1990s, which caused much misery among the regions farmers and generated political demands to build an aqueduct to bring water from the Krishna River to Rayalaseema.
The remnant forests of the Deccan are largely deciduous, dropping their leaves in the dry winter and spring months.
Buckingham Canal, a navigable man-made waterway that runs just behind the coast, allows small boats from the Penna to get to Chennai in the south and the Krishna River delta to the north.
[5][6] Telugu literature has flourished in the Penna basin which produced several well-known authors and poets like Kavibrahma Tikkana Somayajulu, Tallapaka Annamacharya, Pothuluri Veerabrahmendra Swamy, Yogi Vemana, Molla, Rallapalli Anantha Krishna Sharma, Vidvan Vishvam, and C. Ramakrishna Reddy.
Vidhwan Viswam's penneti paata which means "a song of River Penna" is very popular in Andhra Pradesh and in Raayala Seema in particular, it is a topic of study in graduation course Telugu language paper .
Ramakrishna Reddy's "penneti kathalu" represented the tragic and cultural life of the people of Penna valley.
The outcome of ongoing Krishna Water Disputes Tribunal – II is very crucial for the future of Penna river basin.