Comparison of Genetic Algorithm and WASAM model for Real Time Water Allocation: A Case Study of Song Phi Nong Irrigation Project Bhaktikul, K. Mahidol University Soiprasert, N. Royal Irrigation Department Sombunying, W Chulalongkorn University

Introduction Irrigation System Management Water availability : Wet year Normal year Drought year Water requirement varies by weekly / monthly Optimal water supply : supply = demand

Introduction Saving water to next period or downstream projects Decision on real time Limit of available software Mathematical model for complex system

Objectives To determine optimal water allocation in various water supply situation by optimization technique (GA) Song Phi Nong Irrigation Project which covers area of 300,000 rai and 32 irrigation schemes Study area

Study area Seasonal water requirement is in range 0.0 – 5.65 m3/s Max. canal capacity 0.42 – 82.98 m3/s

Irrigation System model - Inflow node - Demand node - Sink node

Problem Formulation Objective function If nodal balance > 0.001 Where di = irrigation demand for schemes i xi = irrigation supply to schemes i. R1 = coefficient of penalty function (P1) R2 = coefficient of penalty function (P2) If nodal balance > 0.001 If xi > di

Problem Formulation Constraint : 1. Canal flow <= max. canal capacity 2. nodal balance = 0.0 3. supply <= demand

Model development - Written in C Programming - 9 sub routines

Input requirement

Input requirement

Parameters Sensitivity

Parameters Sensitivity

Parameters Sensitivity

Study results Drought period GA model give equity in supply in each canal. The ratio of water supply to demand was nearly equal to 0.6, 0.7, 0.8, and 0.9 in every week. WASAM model can not operate in this period

Study results Normal and flood period GA model give supply in each canal not over demand Both GA and WASAM give the similar results

Study results Q (m3/s) Canal No.

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