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Krishna Rao, G.
- Groundwater Recharge Estimates by Radio-Isotope Method-A Critical Analysis
Authors
1 Department of Geology, Andhra University, Visakhapatnam 530003, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 29, No 1 (1987), Pagination: 180-188Abstract
Isotopes have a wide application in groundwater problems like recharge estimates. Though the results of this method are nearly convincing, the concept behind the method is not. The radio-active tracer movement in the unsaturated zone represents only soil moisture transport which is not available for exploitation as groundwater. The exploitable groundwater corresponds to the 'gravitational water' component of the infiltrating waters.
- Mineralogical Studies on the Bauxites from Shevaroy Hills, Tamilnadu State
Authors
1 Geology Department, Andhra University, Waltair, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 15, No 1 (1974), Pagination: 58-64Abstract
Bauxites of Shevaroy hills were analysed for their mineralogical composition adopting X-ray and differential thermal analyses, heavy mineral and microscopic studies. Gibbsite and goethite are the ubiquitous and major constituents while boehmite, hematite, lepidocrocite, kaolinite, halloysite and quartz are present in minor amounts in certain samples only. There is a variation in the abundance of these minerals with the grain size of the bauxite. Magnetite, ilmenite, zircon, rutile and garnets are the heavy minerals present.- Tectonic History of Parts of Bhima Basin and its Influence on Groundwater Conditions in Gulburga District, Karnataka
Authors
1 Department of Geology, Andhra University, Visakhapatnam 530003, IN
2 Central Ground Water Board, Western Region, Jaipur, IN
3 Colombo, LK
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 25, No 8 (1984), Pagination: 505-513Abstract
The Southern part of Bhima basin was displaced transversly towards west. The net slip of this fault on the northern part is about 35 km. Second order shears are numerous in the area. Gravity and thrust faults are also observed in the region. Folds of plunging, non-plunging and superposed types are identified. The basin seems to be tilted towards north at 5° or, possibly, the central part of the basin is sunken.
There is a distinct variation in groundwater potentiality between the tectonic and non-tectonic regions of both Archaeans and Bhimas. The water table is invariably shallow along the tectonized zones. The unit area specific capacity of wells in the non-tectonic regions falls below 2.01pm/m/m2 while it varies upto 55.01pm/m/m2 in the tectonic zones. Seepages and springs are located at a number of places in the tectonic zones and also along the 'nala' courses. Their recorded discharges during the summer period vary from 50 to 200 m3/hr.
- Intensity of Pollution of Groundwater in Visakhapatnam Area, Andhra Pradesh, India
Authors
1 Department of Geology, Andhra University, Visakhapatnam 530003, IN
2 Department of Geology, Tribhuvana University, Khatmandu, NP
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 36, No 6 (1990), Pagination: 670-673Abstract
Hydrogeochemical study indicates that the intensity of pollution of groundwater was not so alarming up to 1975 in Visakhapatnarn area, but after that it rapidly increased due to sweeping growth of industrial and urban activities and lack of environmental protection.Keywords
Hydrogeology, Pollution, Groundwater, Visakhapatnarn Area, Andhra Pradesh.- Hydrogeochemical Zoning in Crystalline Terrain and its Significance to Water Quality
Authors
1 Hydrogeology Laboratory, Department of Geology, Andhra University, Visakhapatnam - 530003, Andhra Pradesh, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 49, No 6 (1997), Pagination: 715-719Abstract
Geochemical variations observed between shallow aquifer waters (SAW) and deeper aquifer waters (DAW) indicate better quality in DAW.Full Text
- Geochemical Changes Due to Weathering Under Different Environmental Conditions in Parts of Eastern Ghats
Authors
1 Department of Geology, Andhra University, Visakhapatnam - 530 003, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 48, No 4 (1996), Pagination: 427-437Abstract
Geochemical changes in weathering profiles from khondalites, charnockites and leptynites at different altitudes in the Eastern Ghats were studied. Chemical changes of major oxides (SiO2, Al2O3, Fe2O3) and minor oxides (CaO, MgO, K2O, Na2O) in the weathering profiles and the percentage of net loss or gain of each constituent reveal that climate and topography have significant role on their behaviour.Keywords
Geochemistry Weathering, Khondalites, Charnockites, Eastern Ghats, Andhra Pradesh.- Decomposition of Primary Minerals and the Process of Bauxitisation in Shevaroy and Kolli Hills, Salem District, Tamil Nadu
Authors
1 Geology Department, Andhra University, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 17, No 4 (1976), Pagination: 530-538Abstract
The bauxite deposits of Shevaroy and Kolli hills have been investigated to understand the processes involved in decomposition of the primary minerals leading to bauxitisation. The charnockitic suite of rocks underlying the bauxite deposits consists of quartz, plagioclase and potash feldspars, ortho- and cline-pyroxenes, garnet and secondary hornblende. During weathering, feldspars directly give rise to gibbsite and sometimes through kaolinite as an intermediate product. Under similar drainage conditions plagioclase feldspars in particular and mafic rocks in general are found to be more favourable for direct bauxitisation than potash feldspars and felsic rocks. The secondary product from pyroxenes (and hornblendes) is usually goethite but rarely clay minerals of nontronite group. Gibbsite in minor amounts is believed to be another secondary mineral in addition to goethite in the case of garnet alteration. Quartz is subject to dissolution and is replaced by gibbsite and goethite towards the final stages of bauxitisation. Order of mineral stability for weathering is, feldspars=pyroxenes < garnet < quartz.
Secondary enrichment bauxite and/or laterite as a result of migration and reprecipitation of aluminium and iron hydroxides has been observed. Hematite and boehmite are believed to have been formed in the advanced stages of weathering under an acidic environment during these secondary processes.