Brief Description of the Basin

• The Pennar basin extends over an area of 55,213 sq. km which is nearly 1.7% of the total geographical area of the country.

• Out of the total area of the basin, 6,937 km² lies in Karnataka and 48,276 km² in Andhra Pradesh.

• The basin lies between east longitudes of 77º04' and 80º10' and north latitudes of 13º16' and 15º52'.

• It is bounded on the north by the Erramala range, on the east by the Nallamala and Velikonda ranges of the Eastern Ghats, on the south by the Nandidurg hills and on the west by the narrow ridge separating it from the Vedavati valley of the Krishna basin.

• The basin lies in the States of Andhra Pradesh and Karnataka.

Drainage Area (Km²)

Statewise Drainage Area (Km²)

Name of State

Drainage area

Andhra Pradesh

48,276

Karnataka

6,937

Total Drainage Area (Km²)

55,213

Geology

The geology of the drainage basin is predominantly formed from Archean rocks, principally granitic intrustives into metamorphic schists. The Archeans in this region comprise biotite and hornblende granite-gneisses, granodiorite, diorite, and pegmatite. Of secondary importance are the Dhawar metamorphics comprising of phyllites, slates, schists with chlorite, biotite, garnet, staurolite, kyanite, silllimanite and hornblende. In the central part of the basin, the dominant rocks belong to the Cuddapah and Kurnool groups consisting of conglomerates, sandstones, shales, dolomites, limestones and cherts. These are intruded by doloritic and basaltic igneous materials in many places. In the coastal regions major sediments are laterites and recent alluvium.

Soil of the Basin

The important soil types found in the basin are red soil, black soil, sandy soil and mixed soil. The culturable area of the basin is about 3.54 M-ha which is about 1.8% of the culturable area of the country.

Land use of the Basin

Under major land uses in the Pennar basin, forests account for 21% of the area whereas nearly 12% area falls under barren land. Net sown area is 36% of the total basin area while total culturable area is about 55%. In the basin, double crops are taken over very small, about 1.66 % area.

Climate of Basin

The catchment receives rainfall both during the south-west and north-east monsoons. The rainfall during the non-monsoon period is not significant. The north-east monsoon (October through January) provides a little precipitation but the predominant rain falls when the southwest monsoon (June through September) occurs. Post monsoon cyclonic activity in the Bay of Bengal during September and October produces an increased rainfall in the coastal region. The mean annual rainfall within the drainage basin varies from about 550 mm around Anantapur area to 900 mm around Nellore.

From the temperature records, it is seen that the mean maximum daily temperature varies from 40.3ºC observed at Cuddapah to 34.7°C observed at Arogyavaram and the mean minimum daily temperature varies from 20°C observed at Nellore to 15.3°C observed at Arogyavaram. In general, humidity is high during the monsoon period and moderate during non-monsoon period. The relative humidity in the catchment of Pennar ranges from 21 to 84 percent.

Water Potential of the Basin

Surface Water potential

6.32 km³

Ground Water potential

4.93 km³

Water Utilization

Surface Water Utilization

Drinking purposes

Irrigation purposes

Ground Water Utilization

Drinking purposes

Irrigation purposes

Principal Tributaries

The principal tributaries of the Pennar River are the Jayamangali, the Kunderu, the Sagileru, from the left and the Chitravati, the Papagni and the Cheyyeru from the right.

Major Projects

Somasila Reservoir and Sathanur Reservoir

Water Quality of the Basin

Rivers in semi-arid areas are characterized by wide variations in the annual flows and poor quality of water. Pennar River also has a semi-arid catchment. Water of the Pennar River up to Anantpur and Cuddapah is not of good quality for irrigation and drinking due to large quantities of carbonates and bicarbonates. The fluoride concentration is also high due to the presence of soluble salts and fluorides from the rocks and soils in the catchment. Due to poor quality of water, yield from irrigated crops is very poor. In case of paddy, only special saline resistant varieties could be grown with low yields. While the soils nearer the ridges are generally good, nearer the valleys the soils are saline or alkaline due to water logging and deposition of salts. However, the quality of water of the tributaries of Pennar is good and hence there is good irrigation development in the lower reaches. Kundu River, a major tributary of the Pennar carries water of K.C. Canal which draws good quality water from Tungabhadra. Even though the catchments of Tungabadra and Pennar are close by (the basin of Vedavati lies in between), there is large difference in the quality of water of these rivers.

Problems in the  Basin

The Pennar water possess high silt load during monsoon period resulting acute drinking water problems for people in rural areas who directly depend on it. In Andhra Pradesh, ground water occurs under unconfined and semi confined conditions. Rainfall is the principal source of recharge; the others being percolation of river water during high flow periods and seepage of irrigation water. During summer (low flow) period, ground water contributes to baseflow. Among the cations and anions present in the ground water sodium and chloride are predominant in Andhra Pradesh region. Concentration of cations and anions are in the order: Na > K > Ca > Mg; Cl > SO₄ > F. Non-carbonate hardness is present in the region.

The indices of salt-water contamination like Mg/Ca, Na/Ca indicate that the ground water in the entire area is slightly contaminated with sea water. Based on this fact, some people have hypothesized that this area was probably inundated by seawater in the past. Seawater from the Bay of Bengal is the main contributor to salinity in the coastal areas and this is caused by the reduction in the Pennar water flow. The problem of saline water intrusion in the fresh water zone gets severe during the dry period when the Pennar and its tributaries face a drastic fall in river flow. This situation is worsening and might lead to a terrible environmental hazard in the future unless a suitable remedial action is initiated.

Mythology

The Pennar or the Uttara Pinakini is one of the major rivers of Indian peninsula flowing east and draining into Bay of Bengal. It is the next largest river to Cauvery in the Peninsula. Pennar River is locally known as Penneru; it is also called ‘Henne’ which means Penna in Telugu language. The name Pinakini is associated with ‘Pinaka’ the bow of Siva or Nandeeswara, the presiding deity of Nandi hills, the place of origin of the river