Geoenvironmental appraisal of Vijayawada-Guntur-Tenali area, Andhra Pradesh
Jagannathan, V.; Sharma, R.V.S.; Subba, R.M.V.
Special Publication Series - Geological Survey of India 48(1): 77-80
1997
Document Number: 465517
The government of Andhra Pradesh has taken up urbanisation of Vijayawada-Guntur-Tenali areas of the state and demarcated 1,665 sq km for development by 2001 A.D. It is situated on the banks of Krishna river. The other important rivers are Budameru, Penumaka and Peddavagu. The average rainfall is 930 mm. Clayey, black regur and red ferruginous soils occur in the area. Residual hills, pediments and Krishna delta form the major parts of the area. The Archaean rocks consisting of khondalite, charnockite and granite gneiss are exposed in the western parts. Upper Gondwana rocks, mainly sandstones, with thin clay intercalations occur as small linear patch in southern parts. Quaternary sediments consisting of gravels, sands, sandy clay, black clay occur in eastern part of Krishna delta. Geophysical surveys have indicated sediment thickness ranging from 35 m to 1,000 m, underlain by faulted basement blocks. The area slopes towards east/southeast. Vijayawada town forms the "apex" of Krishna delta. The western part consists of erosional landforms like denudational hills, inselberg, pediment and pediplain. The eastern part consists of depositional landforms like flood basin deposits, levees and palaeochannels. The groundwater quality and yield is very good in palaeochannels whereas the quality of groundwater indicates alkalinity in areas occupied by Gondwana and archaeans. Various polluting radicals in groundwater samples, along with permissible limits of drinking water standards (in brackets) are pH 7.0 to 9.35 (6.5 to 8.4); total hardness as a CaCo (sub 3) 870 to 1,170 ppm (200 ppm); Cl 630 to 990 ppm (250 ppm); F 1.96 ppm (1.7 ppm) and No (sub 3) 350-489 ppm (45 ppm). The occurrence of unconsolidated sediments, buried gullies and channels, active tectonic adjustments and floods, are factors making the eastern parts of the area unsuitable for urbanisation. The buried channel of Krishna river is a vital source of groundwater for both irrigation and potable use. This area should be protected from pollution. The reactivated channel should be avoided for civil constructions. Flash floods are common in valley plains of Budameru, Penumaka and Peddavagu streams making the area unsuitable for urbanisation.