PERFORMANCE EVALUATION AND ENERGY OPTIMIZATION OF CENTRIFUGAL PUMPS FOR AGRICULTURAL WATER SYSTEMS IN PAKISTAN UNDER A CHANGING ENERGY AND WATER LANDSCAPE

Efficient water pumping is critical to sustaining agricultural productivity in water-stressed and energy-deficient regions. This study evaluates the hydraulic performance and energy efficiency of locally manufactured centrifugal pumps commonly used for groundwater extraction in Pakistan's agriculture sector. Field and laboratory-based testing was conducted on eight centrifugal pumps with varying impeller and casing sizes to develop performance curves under different operating conditions. Key metrics, including flow rate, head, energy input, and associated hydraulic losses, were measured to compute actual pump efficiency. The results indicate that oversized pumps and mismatched motor--impeller combinations lead to substantial energy wastage—up to 37% over design in some cases. Impeller trimming, a conventional technique used to align pump output with demand, was experimentally tested and found to reduce pump efficiency from 78.5% to 67.1% across trimmed stages. Larger pumps (e.g., 5″- 6″ casings) exhibited higher efficiency (up to 76.5%) than smaller counterparts (e.g., 2.5″-3″ casing at 63.2%). The study also highlights significant head losses due to fittings like bends, reducers, and check valves, emphasizing the need for optimal pump system design. These findings underscore the importance of optimized pump selection, performance monitoring, and energy efficiency retrofits in agricultural water systems, particularly under rising energy costs and declining groundwater tables. In the face of climate variability and water scarcity, such optimizations present scalable solutions for resilient and sustainable irrigation infrastructure in South Asia and beyond.