Groundwater Quality Assessment with Special Reference to Sulphate contamination in Bemetara District of Chhattisgarh State and Ameliorative Measures (PDS NO. NIH-29_2017-70)

Abstract

Groundwater is one of the most important sources for drinking water supply in the state of Chhattisagrh. The groundwater of Bemetara district is affected by sulphate contamination reported by Public Health Engineering Department, Durg. Therefore, Bemetara district is selected for the purpose-driven study of sulphate contamination in groundwater in collaboration of Water Resources Department (WRD), Govt. of Chhattisagarh, Raipur and NCCR, CGWB, Raipur. Based on the suggestion of WRD, Raipur the study is focused on Maniyari shell formation region for tracking the problem in a real sense. Hence, the study area is extended from the district Bemetara to Maniyari shell formation region. The high concentration of sulphate in groundwater is reported due to the dissolution of gypsum veins present within Maniyari shale formation. High concentration of sulphate in groundwater causes gastrointestinal irritation. Seventy-two groundwater samples were collected from different drinking water sources extensively being used in the study area during pre- and post-monsoon seasons of the years 2018-19 and 2019-20 and analyzed for determination of physico-chemical parameters and metal concentrations. Hydro-chemical data for the pre- and post monsoon seasons were processed as per BIS and WHO standards to examine the suitability of groundwater for drinking purposes. TDS, Total hardness, Calcium, Magnesium, Sulphate and Nitrate and metal concentrations viz; Fe, Mn, Pb, Cd and As in the groundwater at few locations in the study area were found exceeded the maximum permissible limit prescribed by BIS (2012) for drinking water. The quality of the groundwater was found to vary from place to place for varying depth of water table. Ionic relationships were developed and water types were also identified. Spatial distribution maps were prepared in the form of contour diagrams to identify degraded water quality zones, and also the possible sources of pollution and specific parameters not conforming to drinking/ & irrigation water quality standards. Suitability of ground water for irrigation purpose was also assessed on the basis of total soluble salts, SAR, and RSC, and found to be fit for irrigation. Classification of water was made using Pipertrilinear diagram, Chadha’s diagram and U.S. Salinity Laboratory Classification. Majority of the samples from the study area was detected to belong to Ca-Mg-Cl-SO4 or Ca-Mg-CO3-HCO3 hydrochemical facies, and fall under water types C3-S1 followed by C2-S1 for both pre- and post-monsoon seasons. The C3-S1 type water (high salinity and low SAR) cannot be used on soils with restricted drainage. Hydro-chemical data was also processed to understand the