INVESTIGATING THE EFFECT OF SAMPLING POINT DISTANCE ON IKPOBA RIVER WATER QUALITY USING LEAST SQUARE REGRESSION MODEL

Abstract

In this study, the sampling point distance as it affects Ikpoba River water quality was examined in order to ascertain the quality of the river before and after waste discharge. Water samples were taken from eight (8) different locations (at distance 750 m, at 150 m interval); covering the locations of wastewater release, upstream and downstream points. Samples were taken from the river for analysis twice every month in March, May and July, 2014. Samples were analyzed for pH, Electrical conductivity, Ca, colour, turbidity etc; using WHO standard methods for water quality tests. Results obtained showed that the Water Quality Index of the river water was poor at discharge point but improved as the sampling distance increased. The month of March had the worst Water Quality Index value of  -5429792.89 at STN1, distance 0 m while the best WQI was in May (-457153.58) STN8 at 750 m. The model equations explaining the correlation between the computed WQI and sampling station distance are: Y = -4.112E6 + 1836.272X (March), Y = -1.848E6 + 2184.649X (May) and Y =-2.185E6 + 678.695X (July) respectively. One-way analysis of variance result (ANOVA) at 95% confidence interval revealed that there is a strong relationship between sampling distance and WQI for months of May and July except March. The study revealed that there is a correlation between sampling distance and water quality and hence recommends adequate effluent treatment before disposal. Also, waste disposal into the stream should be done at considerable distance from downstream users.