Geophysical and Geochemical Approach for Seawater Intrusion Assessment in the Godavari Delta Basin, A.P., India

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

Groundwater flow modeling of Kwa Ibo river watershed, Southeastern Nigeria

Groundwater flow modeling of 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, called Benin Formation, is of Quaternary to Recent age. Potential aquifer zones earlier delineated using the geoelectrical resistivity soundings and well inventory in the area formed the basis for groundwater flow modeling. The watershed has been modeled with a grid of 65 rows x 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 varying from 3 to 14.5 m/day. Natural recharge due to rainfall formed the main input to the aquifer system and abstraction from wells, the 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 ten-year study period was recorded in 1996, while the lowest was recorded in 1991. The computed groundwater balance of 55274m3/day was comparable to that estimated from field investigations. Results from the modeling show that abstraction is very less compared to groundwater recharge. Hence there is the possibility for additional groundwater exploitation in the watershed through drilling of bore holes. Keywords: groundwater, modeling, permeability, recharge, Kwa Ibo RiverGlobal Journal of Geological Sciences Vol. 3(2) 2005: 169-17

Low cost waste treatment methods for treating pharmaceutical wastes

Low cost waste treatment methods for treating pharmaceutical waste