Hydrogeochemical assessment of groundwater quality for drinking and irrigation applying groundwater quality index (GWQI) and irrigation water quality index (IWQI)

In recent times, the contamination of groundwater in the extended part of Chota Nagpur Plateau becomes a big concern. The demand of high-quality drinking and irrigation water has been significantly augmented. Consequently, productivity and fertility of soils are being reduced in the recent years due to use of low quality irrigation water. Thus, it is crucial to know the groundwater quality for the appropriate planning and management of groundwater resources to determine its use for drinking and irrigation purposes. Therefore, the principal objectives of this study are (i) to evaluate the magnitude and spatial variations of groundwater quality using the Groundwater Quality Index (GWQI) for drinking and (ii) to examine the irrigation suitability of groundwater using irrigation water quality index (IWQI). Sodium absorption ratio (SAR), Soluble sodium percentage (SSP), Magnesium hazard (MH), Kelly's index (KI), Permeability Index (PI) have been applied for suitability of irrigation water. Result showed that in 2021, GWQI values vary from 51.75 to 171.18 and seven blocks of the Purulia district among twenty blocks have poor drinking water quality while in 2022 it ranges from 70.27 to 178.45 and eight blocks stand poor water quality. In terms of irrigation water quality, Purulia II and Hura blocks come under the ‘doubtful’ or ‘poor ‘categories in pre and post-monsoon seasons for both the years. Hydro-chemical facies through Piper, USSL and Durov's diagram showed medium to high salinity and low to medium sodium hazards in this region. Feldspar and biotite minerals of granite and gneiss accelerate the bicarbonate and chloride ions in groundwater. Non point sources are also responsible for water quality deterioration in this agricultural dominated region. These research findings will help to policy makers and administrators for the management of groundwater resources and agricultural sustainability particularly in the dryland region.