水文地质与水文工程学报

Source Sustainability of Fractured Anorthositic Aquifer System in the Rarh Bengal and Socio-Cultural Implications

Debasish Bagchi* and Anadi Gayen

Hydraulic properties of fractured rock aquifers in the Bankura anorthosite were determined by test pumping at the Narrah test site in Rarh Bengal. The study area with a moderately high composite development index is socio-economically backward. Geological log showed occurrence of banded gneiss and Bankura anorthosite. The fractured aquifer occurs in depth range from 135.5 to 138.6 mbgl. The discharge is about 4.0 L/s with an air compressor, which was sustainable after 300 minutes of test pumping. A high well recovery of 93.11% shows the sustainability of the anorthositic aquifer. The field-based hydraulic conductivity matches with published mean hydraulic conductivity of anorthosite. Although transmissivity of the aquifer is low (<10 m² /day), calculations show that the bore well would meet water requirement of 11.61% of the population of Narrah, thus aiding in solving the water scarcity problem of the area. Iron contamination in the area is attributed to colonial growth of iron-oxidizing bacteria and absence of ferruginous minerals in the geological log. Solutions to iron contamination are aeration and oxidation, followed by rapid sand filtration by installing iron removal plants through government funded schemes. Due to hydrogeochemical affinity of iron with platinum group elements, especially palladium as a pathfinder element, the area is strategically important for mineral exploration. A judicious management of the fractured anorthositic aquifer is recommended to address the water scarcity problem, which would improve the existing socio-cultural condition. The success can be replicated in other similar areas of the Rarh region with analogous hydrogeological conditions.