Assessment of the Suitability of Groundwater Systems for Irrigation Purposes in Owerri and Environs, Southeastern Nigeria

Abstract

Groundwater quality evaluation for irrigation purposes in Owerri and Environs, Southeastern Nigeria was the sole aim of this research for enhancing effective agricultural production. The study area consists of prolific unconfined aquifer belonging to the continental Benin Formation of Oligocene age. Fourty-two groundwater samples were collected under standard conditions from Owerri and environs and sent to laboratory for analysis. The results of the physical parameters (pH 5.50 – 7.80, electrical conductivity 70.50 – 805.20 and total dissolved solids 42.40 – 580.60) fall within the permissible limit for good irrigation water. The laboratory results of the major ions whose concentrations were milligram per litre are converted to milliequivalent per litre and used to compute the irrigation quality indices. The sodium adsorption ratio (SAR) ranged from 0.10 – 7.85 meq/L with a mean value of 1.40 meq/L while the concentration of soluble sodium percentage (SSP) varied from 3.75 – 26.70 meq/L with an average value of 10.80 meq/L. The concentration of plasticity index (PI) ranged from 15.80 – 60.50 meq/L with a mean value of 35.20 meq/L while the value of residual sodium bicarbonate (RSBC) varied from 0.95 – 2.10 meq/L with an average value of 1.15 meq/L. The value of Kelly ratio (KR) varied from 0.02 – 0.58 meq/L with a mean value of 0.25 meq/L while magnesium adsorption ratio (MAR) ranged from 4.50 – 52.50 meq/L with an average value of 20.10 meq/L. Based on the results of irrigation index parameters analyzed, groundwater systems in the area are suitable for irrigation purposes. The salinity plots, permeability plots and Wilcox diagram further attest that the groundwater systems in the area are suitable for irrigation purposes. It is recommended that groundwater in the area should be harnessed for dry season farming in the area so as to boast food production in the area.