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Coastal lands around Bay of Bengal in Central Godavari Delta are mainly agriculture fields and two times annually paddy crops putting in the study area. Canals of Godavari River are the main source of water for irrigation. Geophysical and geochemical investigations were carried out in the study area to decipher subsurface geologic formation and assessing seawater intrusion. Electrical resistivity tomographic surveys carried out in the watershed-indicated low resistivity formation in the upstream area due to the presence of thick marine clays up to thickness of 20–25 m from the surface. Secondly, the lowering of resistivity may be due to the encroachment of seawater in to freshwater zones and infiltration during tidal fluctuation through mainly the Pikaleru drain, and to some extent rarely through Kannvaram and Vasalatippa drains in the downstream area. Groundwater quality analyses were made for major ions revealed brackish nature of groundwater water at shallow depth. The in situ salinity of groundwater is around 5,000 mg/l and there is no groundwater withdrawal for irrigation or drinking purpose in this area except Cairn energy pumping wells which is using for inject brackish water into the oil wells for easy exploration of oil. Chemical analyses of groundwater samples have indicated the range of salt concentrations and correlation of geophysical and borehole litholog data in the study area predicting seawater-contaminated zones and influence of in situ salinity in the upstream of study area. The article suggested further studies and research work that can lead to sustainable exploitation/use and management of groundwater resources in coastal areas.

Cite this article as: L. Surinaidu, V.V.S. Gurunadha Rao, N. Srinivasa Rao, S. Srinu, Hydrogeological and groundwater modeling studies to estimate the groundwater inflows into the coal Mines at different mine development stages using MODFLOW, Andhra Pradesh, India, Water Resources and Industry, http://dx.Abstract The Singareni Collieries Company Ltd (SCCL) is exploiting coal in the Godavari valley coal fields spread over 5.33 km 2 in Andhra Pradesh, India. In the area, six workable coal seams have been identified in Barakar formation by the analysis of the geologic logs of 183 bore wells. A finite difference based numerical groundwater flow model is developed with twenty conceptual layers and with a total thickness of 320 m. The flow model was calibrated under steady state conditions and predicted groundwater inflows into the mine pits at different mine development stages. The groundwater budget results revealed that the mining area would receive net groundwater inflows of 5,877 m 3 /day, 12,818 m 3 /day, 12,910 m 3 /day, 20,428 m 3 /day, 22,617 m 3 /day and 14,504 m 3 /day at six mine development stages of +124 m (amsl), +93 m (amsl), +64 m (amsl), +41 m (amsl), +0 m (amsl) and -41 m (amsl) respectively. The results of the study can be used to plan optimal groundwater pumping and the possible locations to dewater the groundwater for safe mining at different mine development stages. 2

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Hussainsagar Lake in the heart of Hyderabad City (India) receives toxic substances through five streams draining from a catchment area of 245 km(2). Of particular interest are heavy metals received from urban runoff as well as municipal sewage and industrial effluents. Heavy metals entering the lake get adsorbed onto the suspended sediments, which eventually settle down in the bottom of the lake. In this study, fractionation of metal ions has been studied on the bed sediments of Hussainsagar Lake in order to determine the ecotoxic potential of metal ions. Comparison of sediments with average shale values indicated anthropogenic enrichment with copper, nickel, lead, cadmium, and zinc. The risk assessment code as applied to the present study reveals that 10-17% of manganese, 10-18% of nickel, 14-24% of chromium, 10-19% of lead, 21-30% of cadmium, and 18-28% of zinc exist in exchangeable fraction and, therefore, comes under medium risk category and may enter into food chain. The association of these metals with the exchangeable fraction may cause deleterious effects to aquatic life. The present database will help in formulating guidelines for carrying out dredging operations under restoration programs in the Hussainsagar Lake.

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Abstract:Groundwater flow modelling of the Kwa Ibo River watershed in Abia State of Nigeria is presented in this paper with the aim of assessing the degree of interaction between the Kwa Ibo River and the groundwater regime of the thick sandy aquifer. The local geology of the area comprises the Quaternary to recent Benin Formation. Potential aquifer zones that were delineated earlier using geoelectrical resistivity soundings and borehole data for the area formed the basis for groundwater flow modelling. The watershed has been modelled with a grid of 65 rows by 43 columns and with two layers. Lateral inflow from the north has been simulated with constant heads at the Government College, Umuahia, and outflow at Usaka Elegu in the south. The Kwa Ibo River traverses the middle of the watershed from north to south. The river-stage data at Umudike, Amawom, Ntalakwu and Usaka Elegu have been used for assigning surface water levels and riverbed elevations in the model. Permeability distribution was found to vary from 3 to 14Ð5 m day 1 . Natural recharge due to rainfall formed the main input to the aquifer system, and abstraction from wells was the main output. A steady-state groundwater flow simulation was carried out and calibrated against the May 1980 water levels using 26 observation wells. The model computations have converged after 123 iterations. Under the transient-state calibration, the highest rainfall (and hence groundwater recharge) over the 10-year study period was recorded in 1996, whereas the lowest was recorded in 1991. The computed groundwater balance of 55 274 m 3 day 1 was comparable to that estimated from field investigations. Results from the modelling show that abstraction is much less than groundwater recharge. Hence there is the possibility for additional groundwater exploitation in the watershed through drilling of boreholes.