Comparison of water quality indexes for inland river

ABSTRACT:

The present study assessed water quality parameters and attempts to compare four different Water 

Quality Indexes (WQIs) for consistency, similarity and reliability in assessing the water quality of 

river Benue -an inland river- under wet and dry seasons. The results demonstrate that River Benue 

is continually being polluted in both dry and wet seasons by different sources, particularly domestic 

sewage and storm runoffs from farmlands. The quality of the water generally exceeded 

physiochemical and microbiological infection risk limits recommended in water quality guidelines 

concerning their use for domestic, recreational and irrigational purposes. Proper sewage treatment 

and river quality monitoring are needed to guard against hazards to public health and vulnerable 

river water resources. The WQIs applied were: CCME WQI, BC WQI, Dinius’ WQI and Weighted 

Arithmetic WQI. To evaluate the differences between these indexes, data on ten water quality 

parameters (Temperature, pH, total dissolved solids, electrical conductivity, Nitrates, Phosphates, 

biochemical oxygen demand, dissolved oxygen and faecal coliform count) for two distinct seasons 

from 6 river monitoring sites along the river Benue at Makurdi reach, were used. Significant 

discrepancies were observed in classification results between the Dinius’ WQI and the other three WQIs. Similarly, the WA and BC WQIs showed an over-optimistic rating due to their eclipsing 

limitation. Among others, it was concluded that any of the four indexes except Dinius’ index can be 

adopted but the CCME water quality index would be best suited for assessing water quality in River 

Benue