Abstract
ASSESSMENT OF GROUNDWATER QUALITY IN OKE-OYI IRRIGATION SCHEME, NIGERIA
Prof. Ojediran J. O., *Dr. Adejumobi M. A. and Orowale T. N.
ABSTRACT
Irrigating with poor quality water affects the quality of soils and crops and often results to a reduction of crop yield and this study assessed the groundwater quality in Oke-Oyi irrigation scheme, Kwara State, Nigeria. Twelve (12) sampling points were randomly selected within the irrigation scheme using Global Positioning System (GPS), coordinates were 08o37?N/04o45?E and 08o37?N/04o46?E at an average elevation of 261meters. Groundwater samples were taken during the peak of dry and wet seasons in March and July, 2016 respectively. The physicochemical properties (temperature, pH, Electrical Conductivity (EC), Total Dissolved Solid (TDS), calcium, bicarbonate, magnesium, potassium, sodium, iron, chloride, boron, nitrate and sulphate) were determined on the groundwater samples collected. Spatial distribution maps for each of the tested parameters at the various sampling locations were plotted using ArcGIS 10.0 software. Physico-chemical properties were obtained using American Public Health Association (APHA) procedures and Food Agricultural Organization (FAO) standard to determine its suitability for irrigation. Results showed that temperature, pH, EC, and TDS varied from 27.00-32.70 oC; 7.91-10.57; 437-729 ?S/cm and 251.67- 1948.30 mg/L.Values for calcium, bicarbonate, magnesium, potassium, sodium, iron, chloride, boron, nitrate and sulphate ranged from 163.30-406.70 mg/L; 0.33-0.86 mg/L; 180-195 mg/L; 31.67-75 mg/L; 1350-2102 mg/L; 0.50-1.30 mg/L; 8.17-36.73 mg/L; 0.33-3.33 mg/L; 2.37-6.63 mg/L and 31.67-95.00 mg/L. The mean water quality indices values during the dry season were RSBC (-13.14 meq/L), PI (0.77 meq/L), TH (1198.29 meq/L), MAR (42.66 meq/L), KR (3.14 meq/L). While wet season values were RSBC (-15.69 meq/L), PI (0.73 meq/L), TH (1378.71 meq/L), MAR (42.98 meq/L), KR (2.67 meq/L) respectively. Aside values of K (44.03 mg/L), Na (1668.50 mg/L), SAR (30.30 meq/L), SSP (75.29%) for dry season and wet season values of K (62.05 mg/L), Na (1641.83 mg/L), SAR (27.47 meq/L), SSP (72.44%).Which were slightly high. All other parameters were within the acceptable standard. As the results obtained were compared with guideline values of FAO to determine the suitability for irrigation purposes aside few locations.
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