A Multistage Optimization Approach for Cost Effective Drip Irrigation Design Integrating Life Cycle Cost Analysis

Abstract

This study proposes an optimal design methodology for a pressurized drip irrigation system based on a multistage optimization approach, which sequentially optimizes the selection of lateral, manifold, and mainline pipe diameters. The objective is to minimize the total annualized cost, accounting for both fixed capital costs and energy costs, while ensuring hydraulic feasibility and pressure uniformity across the system. The hydraulic analysis for each pipeline segment is performed using the Hazen–Williams equation to compute frictional head loss, enabling accurate evaluation under varying flow and diameter conditions. A key constraint—maintaining required pressure head at the pump while satisfying pressure-uniformity throughout the network—is integrated into the optimization model, which is explicitly driven by life cycle cost analysis. The model evaluates all feasible single-diameter alternatives for each pipeline segment and systematically selects the most cost-effective configuration. To demonstrate the practical applicability of the proposed approach, it is applied to the design of a drip irrigation system for an apple orchard of size 120 m × 54 m using a Central Manifold Layout (CML). The results show that the optimal hydraulically feasible configuration includes 20 mm laterals, 40 mm manifolds, and 63 mm mainlines, yielding a total annual cost of ₹12,215 (including an annual fixed cost of ₹8,270 and energy cost of ₹3,945), and a cost per unit area of ₹1.82/m². This configuration effectively balances both economic and hydraulic performance, making it a robust and scalable solution for precision irrigation in orchard systems.