1. Introduction
The Subernarekha is a medium basin of the Indian subcontinent. The riverbed of
Subernarekha is believed to contain traces of gold and hence the name. It originates in the
Chhotanagpur hills of Jharkhand and subsequently passes through West Bengal and
Orrisa.Throughout its course, several small rivers meet like Kharkai at Jamshedpur, and Gara
Nallah at Jadugoda etc. Iron ore, bauxite, copper and uranium, minerals are found along its
stretch. The bedrock of the basin is is a preCambrian
hard rock comprising micaschist,
Quartzite, soda granites and dhanjori volcanic. The water quality index is a dimensionless
number with values ranking between 0 and 100. A higher index value represents a good water
quality (Cude, 2001; Pandey and Sundaram, 2002). This numerical index can be used as a
management tool in water quality assessment.