A Comparison of Water Quality Indexes for an 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.

Toxicity of Diphenyltin Chloride on viable count of aerobic bacteria from River Benue.

“…Mean Nitrate values of all samples obtained from the various locations was 8.52±3.40 and though within the maximum limits specified by WHO (2011) of 50mg/L, there is an obvious increase in their concentrations when compared to previous research. This research agrees with the findings of Kondum et al, [15] in the same study area, who reported nitrate levels of between 8.34±0.30 and 14.69±1.35 mg/L. The nitrate values here however vary with the earlier findings of Okenyi et al, [16] who reported very low values of 2.0 and 2.7 mg/L.…”