Development of Multiple Regression Model in Predicting the Dissolved Oxygen Deficit of Ntawaogba River

Abstract

This study developed a multiple regression model for predicting the dissolved oxygen deficit for Ntawaogba River in Port Harcourt, Rivers State Nigeria. The instrument used for field sampling includes 1L sample container, Garmin GPS, EXTEC water equipment/Horiba, BOD bottle, Floaters, Measuring Tape, Stop watch, Ice chest and sample log book.  Ten samples were collected along the river stretch at distance of 100 m apart. Water quality analysis on the samples showed that ammonia and total coli form counts were higher than Federal Ministry of Environment recommended limits and the dissolved oxygen value ranges from 3.65-5.6mg/l. The computed deoxygenating rate constant was 0.38 and reaeration rate constant was 0.99. The Fair ratio, “f” for the river was 2.55; the dissolved oxygen (DO) deficit at initial time was 3.85mg/l and at critical time (1.72d-1) the critical deficit was 2.48 mg/l respectively. Multiple regression model was developed for dissolved oxygen deficit of the study river using appropriate excel software; considering  BOD, temperature and river flow with constant b0b1b2b3 to be 2.690293, 0.899899, -0.16754, and 0.042823 for respective sample points down the river at any point. These results indicated that the river is polluted and the fluctuation in DO values was attributed to constant waste discharges into the river from various sources and the hydraulic condition of the river.The study recommended that waste discharge into the river should be discouraged and monitored to mitigate further degradation.