Mathias Nzitiri Bwala

Keywords: Non-Point Pollution, Irrigation, River Ngadda, Runoff, Water Quality

Abstract

The study aimed at assessing the effect of irrigational activities on water quality of river Ngadda, Maiduguri, Borno State, Nigeria. Samples for the water quality analysis were collected biweekly for eleven months period from three sampling stations. The water qualities parameters Total Dissolved Solids (TDS), Dissolved Oxygen (DO), potentia Hydrogenii (pH), phosphate, nitrate, zinc, iron and copper concentrations were analyzed using standard method in the laboratory. Temperature was measured in-situ using mercury thermometer. The mean temperature ranges from 21 – 21.2 0 C during irrigational regime and 22.2 – 23 0 C during non – irrigational periods, phosphate concentration ranges from 0.54 – 0.64 mg/L during irrigational regime and 0.40 – 0.45 mg/L during non – irrigational periods, nitrate concentration ranges from 0.87 – 0.90 mg/L during irrigational regime and 0.73 – 0.81 mg/L during non – irrigational periods, TDS ranges from 238.5 – 243.3 NTU during irrigational regime and 224.6 – 244.2 NTU during non – irrigational periods. The DO values for both irrigational and non – irrigational period ranges from 15.2 – 19.4 mg/L. The mean Iron concentration ranges from 0.12 – 0.21 ppm during irrigational regime and 0.31 – 0.41 ppm during non – irrigational periods. The study revealed that the irrigational activities was a seasonal potential threat to river’s water quality although there were other constant non – seasonal potential threats like effluent from Maiduguri Water Treatment Plant, Maiduguri Abattoir house, dyeing industries e.t.c. Temperature, phosphate concentration, TDS, DO, pH, zinc concentration and copper concentrations were all within the national permissible limits set by National Environmental Standards and Regulations Enforcement Agency (NESREA) whereas nitrate and iron concentrations were slightly above the set national limits. The continuous environmental compliance monitoring and enforcement outreaches by NESREA, Borno State Field Office, Maiduguri to polluters (facilities polluting the river) is gradually paying off as the concentration of phosphate, nitrate, TDS and DO reveal a great improvement from the values of previous studies.