EVALUATION OF GROUNDWATER QUALITY AND PERFORMANCE OF HORMAT-GOLINA DRIP IRRIGATION SYSTEM, KOBO GIRANA VALLEY, NORTHERN ETHIOPIA

Abstract

Groundwater is the primary irrigation resource in the study area. The evaluation focuses on groundwater quality and the performance of the Hormat Golina drip irrigation system. The assessment of drip irrigation scheme performance is essential for understanding irrigation impacts, identifying gaps, and enhancing system efficiency. This study evaluated groundwater quality, pump performance, water delivery from the main line to emitters, and overall system effectiveness. Data collection involved secondary sources and primary methods such as field measurements of water flow rates and pressure, household surveys, key informant interviews, focus group discussions, and laboratory analysis of groundwater samples. Analytical tools used included VANASAN PSP Version 2009.02 for pump performance, CropWAT Version 8.0 for crop water requirements, AutoCAD Civil 3D for design visualization, ArcGIS for spatial analysis, and Microsoft Excel 2016 for data organization and statistical analysis. Groundwater quality was assessed using physicochemical methods, comparing current and previous data against FAO and WHO guidelines for irrigation and water supply. Key parameters analyzed included pH, EC, TDS, Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO₃⁻, CO₃²⁻, SO₄²⁻, Cl⁻, and SAR. The findings indicated that both current and past groundwater conditions are suitable for irrigation and water supply purposes. The groundwater discharge flow results showed that borehole efficiency remained consistent with both current and previous design flow rates. The submersible pump delivered a discharge of 52 L/sec with a total dynamic head (TDH) of 107-111.08 m. The riser velocity was 2.1 m/sec, and the delivery velocity was 1.88 m/sec. The pump required 80.83 kW of power with an efficiency of 70.06%. The motor, with a diameter of 10 inches, operated at 92 kW and 50 Hz, achieving an efficiency of 85%. While the current performance metrics are higher than previous results, they fall within the acceptable tolerance limits outlined in ISO 9906 Annex A. The drip irrigation experiment yielded the following results: DU was 55.64%, Qvar was 72.63%, CV was 0.54 L/hr., UC was 46.10%, EU was 51.47%, and AU was 46.10%. The operating pressure was 0.65 bars. This implies that the drip irrigation system performance of the scheme is poor. Key issues identified during the field study included emitter clogging, uneven water distribution, mechanical problems, and insufficient training for the Irrigation Water Users Association. Therefore, the final recommendations are, replace the submersible pump and lateral lines, address water sharing conflicts, provide an additional power source, offer technical training for beneficiaries, pump operators and valve operators and establish a seasonal evaluation structure for the irrigation scheme