Assessment of Groundwater Quality of the Central Gangetic Plain Area of India Using Geospatial and WQI Techniques

Abstract

Suitability of water quality for the drinking and irrigation purposes is indispensable for the endurance of life and sustainability of the ecosystem. The present study is aimed to evaluate the groundwater quality for suitability of drinking and irrigation purposes in the central Gangetic plain area (Bhagarpur district, Bihar), India using the geo-spatial and waterqaulity index (WQI) techniques. Groundwater samples were collected randomly from 45 locations in the pre-monsoon (April -May) and post-monsoon (October-November) season respectively during the period between 2015 and 2016. The different major water quality parameters such as pH, Electrical Conductivity (EC), Total hardness, Calcium (Ca++), Magnesium (Mg++), Sodium(Na+), Potassium (K+), Chloride (Cl-), Carbonate (CO3—), Bicarbonate (HCO3-), and Fluoride (F-) were analyzed using standards methods. Sodium adsorption ratio (SAR) and residual sodium carbonate (RSC) were estimated for suitability of irrigation uses. Pearson’s correlation coefficient was calculated to measure the degree of relation between groundwater variables. The spatial variation maps of these groundwater quality parameters were generated through Inverse distance weightage (IDW) interpolation technique in Arc-GIS software. The pH value of 4.4% of the groundwater samples was found exceeding the acceptable limit established by the WHO (2011)/BIS (2012). Clvalues ranges between 3.24 to 28.74 mg/l-1 in the pre-monsoon season and from 2.50 to 64.98 mg/l-1 in post-monsoon season. Magnesium are cross the limits (<50 mg/l-1) of WHO/BIS in both the pre- and post-monsoon seasons. The F- concentration is higher in both the pre-monsoon and post-monsoon season. The water quality index (WQI) indicates 4.44% of the pre-monsoon samples are good for drinking purposes, whereas the value increases to 31.11% during the post-monsoon in the study area. The higher value of RSC was portrayed in the entire Naugachhia block and the eastern part of the Goradih block for both the season. The higher concentration of sodicity problem is portrayed in the entire Goradih block, north-east of Gopalpur block, and south-west of Naugachhia block for both the pre-monsoon and post-monsoon season. These results will be help planners, decision makers, local peoples, and Government to take necessary measures.