Application of Water Quality Indices and Dissolved Oxygen as Indicators for River Water Classification and Urban Impact Assessment

Environ Monit Assess (2007) 132:93110 DOI 10.1007/s10661-006-9505-1

Application of Water Quality Indices and Dissolved Oxygen as Indicators for River Water Classification and Urban Impact Assessment

Prakash Raj Kannel & Seockheon Lee &

Young-Soo Lee & Sushil Raj Kanel &

Siddhi Pratap Khan

Received: 7 July 2006 /Accepted: 15 September 2006 / Published online: 6 February 2007 # Springer Science + Business Media B.V. 2007

Abstract The usefulness of water quality indices, as the indicators of water pollution, for assessment of spatialtemporal changes and classification of river water qualities was verified. Four water quality indices were investigated: WQI (considering 18 water quality parameters), WQImin and WQIm (considering

five water quality parameters: temperature, pH, DO,

EC and TSS) and WQIDO (considering a single parameter, DO). The water quality indices WQImin,

WQIm and WQIDO could be of particular interest for the developing countries because of the minimum analytical cost involved. As a case study, water quality indices were used to evaluate spatial and temporal changes of the water quality in the Bagmati river basin (Nepal) for the study period 19992003. The results allowed us to determine the serious negative effects of the city urban activity on the river water quality. In the studied section of the river, the water quality index (WQI) was 71 units (classified as good) at the entry station and 47.6 units (classified as bad) at the outlet station. For the studied period, a significant decrease in water quality (mean WQI decrease=11.6%, p=0.042) was observed in the rural areas. A comparative analysis revealed that the urban water quality was significantly bad as compared with rural. The analysis enabled to classify the water quality stations into three groups: good water quality, medium water quality and bad water quality. WQImin resulted in overestimation of the water quality but with similar trend as with WQI and is useful for the periodic routine monitoring program. The correlation of WQI with WQImin and

DO resulted two new indices WQIm and WQIDO, respectively. The classification of waters based on WQIm and WQIDO coincided in 90% and 93% of the samples, respectively.

Keywords Water quality index . Water quality indicator. Dissolved oxygen . Bagmati river

P. R. Kannel (*) : S. Lee (*)

Water Environment & Remediation Research Center, Korea Institute of...