Assessment and Characterisation of Groundwater Quality Using Weighted Arithmetic Water Quality Index (WAWQI) in Some Selected Villages Near Namchik- Namphuk Coal Field, Changlang District, Arunachal Pradesh, India

Abstract

This study is concerned with the assessment of water quality in 5 villages in and around the Namchik Namphuk Coal field under Kharsang Circle in Changlang District of Arunachal Pradesh. A total of 11 water samples were collected, and standard laboratory assessments were conducted to determine various physicochemical properties, viz. Turbidity, pH, hardness, alkalinity, TDS, Cl, SO42-, F, NO -, Fe, As, Pb, Cr, Zn, Cd, Ni, and Oil and grease. Along with that, a household survey comprising 114 households was undertaken to understand the potential problems and issues related to water. Based on the results and considering the acceptable limits for different parameters in drinking water, as per the Bureau of Indian Standards (BIS) IS 10500: 2012, the WQI has been worked out using the WAWQI Method. It has been found that only 1 sample can be considered as excellent, 2 samples were good, 1 sample each in the poor and very poor categories, while 6 samples were found to be unsuitable for drinking. High turbidity (avg. 5.25 NTU), low pH (avg. 6.37, indicating acidification), and elevated average concentrations of heavy metals such as Pb (0.016 mg/L) and Cd (0.008 mg/L) are key factors degrading the overall water quality. The findings suggest a shortage of quality drinking water, and the proximity and exposure to mining-related waste could be the cause of contamination. Proper disposal of mine waste, restrictions on stockpiling near water sources and overall restrictions on illegal mining operations are the need of the hour to tackle these issues.