Course The Penna river has several sources and mouths. 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 river is seasonal, its main source of the water being from rains. Therefore, it appears like small stream during periods of drought. The major tributaries of the Penna are the Jayamangali,
Kunderu and
Sagileru from the north, and
Chitravathi,
Papagni and
Cheyyeru from the south.
Karnataka The Penna river rises at at 11 km southwest of
Chikkaballapur in Chennakesava Range of
Nandi Hills in
Karnataka. It begins flowing to the northwest at its source, near the town of Maralur. It flows for 48 km towards the north through the
Kolar and
Tumkur districts in Karnataka before entering
Andhra Pradesh State at
Hindupur Sri Sathya Sai district.
Ananatapur At 69 km, the Penna meets the Kumudavati river. At 82 km, the Penna meets the Jayamangali river near the town of
Hindupur in
Sri Sathya Sai district. The Jayamangali river rises in
Tumkur district and traverses 77 km in northeast direction before joining the river on the left bank. The Penna flows almost northwards for the next 146 km from the confluence of Jayamangali. After traversing 67 km in Anantapur district, the Penna reenters Karnataka at
Pavagada Taluk in Tumkur district at 115 km from its source. After traversing 13 km in Tumkur district again, it reenters Andhra Pradesh in
Kalyandurg Taluk in Anantapur district at 128 km from its source. The Penna turns east at
Penna Ahobilam and flows through Marutla and Katrimala forest reserves and near towns like
Tadipatri.
Kadapa 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 meets its major tributary Chitravati at Gandalur near the
Gandikota at 336 km from its source. The Chitravati rises near the
Chikballapur town in the Chikballapur district of Karnataka and traverses 218 km in northeast direction in Kolar, Anantapur and Cuddapah districts before joining the Penna on the right bank. 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 rivers Papagni and Kunderu meets the Penna near
Kamalapuram. 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 river continues in southeastern direction and cuts across the Nallamala hills. The river meets sagileru and turns east. The Sagileru rises in
Prakasam district and flows south to meet the Penna. The Penna river meets Cheyyeru at Boyanapalli and Gundlamada near the
Sidhout on the right bank. The Cheyyeru river is formed by the confluence of the rivers Bahuda and Pincha that originate in the
Chittoor district of Andhra Pradesh. The two streams join at
Rayavaram and flows towards north for 87 km before joining the Penna.
Nellore 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 river flows near the towns like
Atmakuru,
Kovur,
Jonnawada,
Sangam and
Nellore. It meets two minor tributaries, the Boggeru and the Biraperu near the
Sangam town. The Boggeru rises in Boggu Venkatapuram and joins other minor streams before meeting the Penna river. The Biraperu is a small stream which carries rainfall of the north east portion of Nellore, Udayagiri and Kavali Mandals to the Penna river. It finally joins the Bay of Bengal at near Utukuru at 597 km from its source.
Basin The
watershed of the Penna and its tributaries covers part of the southern
Deccan plateau, including most of the
Rayalaseema region of
Andhra Pradesh and part of
Karnataka. The
Kolar Plateau forms the divide between the Penna watershed and those of the
Kaveri,
Ponnaiyar, and
Palar rivers to the south. The Penna drains the northern portion of the
plateau, which includes parts of
Kolar and
Tumkur districts in
Karnataka. The
Krishna River and its tributaries drain the Deccan plateau to the west and north of the Penna's watershed, and the low
Erramala hills forms the northern divide of the Penna basin. The upper watershed of the Penna includes
Cuddapah District, central and eastern
Anantapur District, the southern part of
Kurnool District, northwestern
Chittoor District. ;Estuary The
estuary of the Penna river extends 7 km upstream from the Bay of Bengal. Tidal influence and salt water extends further upstream during the November to June dry season. Coastal dunes as high as 7 meters form around the river mouth. Upputeru tidal creek, 15 km in length, and Isakapalli lagoon, separated from the Bay of Bengal by the Isakapalli barrier island, 180 m long and up to 3 m high, form the main coastal
wetlands. The lower basin of the Penna is largely made up of ancient
Archean rocks, principally
granite and
schist. The lower basin is made up of young sediments, including
laterite and recent
alluvium. ==Climate==