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1st Int. Transborder Conf. of the Timor Island: Timor %u2013 Science without borderDili, 7-8 May 2025177Hybrid DRBEM-FEM Approach for Modeling Water Infiltration in Agricultural Irrigation SystemsM Lobo1*, P. A. S. Wurm2, M. S. M. Nur3, R. D. Guntur1, and E. K. D. Kette11 Department of Mathematics, Nusa Cendana University, Indonesia2 Faculty of Science and Technology Charles Darwin, University Darwin NT 0909, Australia3 Department of Agrotechnology, Nusa Cendana University, Indonesia*Corresponding author: maria_lobo@staf.undana.ac.idAbstractThis study introduces a hybrid numerical framework combining the Dual Reciprocity Boundary Element Method (DRBEM) and the Finite Element Method (FEM) to model water infiltration dynamics in agricultural irrigation systems. Accurate prediction of infiltration behavior is essential for improving irrigation efficiency and minimizing water loss in arid and semi-arid regions. The proposed model couples FEM, used to simulate flow within heterogeneous soil zones, with DRBEM, which efficiently models the influence of semi-infinite or open boundary domains. A circular domain was used to validate the model, with FEM applied to the interior region (radius r=1) and DRBEM to the exterior annular region (radius r=1 to r=2). A known analytical solution, %u03a6=1%u2212r2, was prescribed as the boundary condition. The model achieved a root-mean-square error (RMSE) of 0.0034 and a maximum absolute error of 0.0081 when comparing DRBEMderived flux at the interface with FEM-derived gradients. Doubling the number of interface nodes from 16 to 32 further reduced the RMSE to 0.0016, indicating good convergence properties. These results confirm that the hybrid approach accurately maintains continuity of both potential and flux across the interface. The flexibility of this method makes it suitable for simulating water infiltration in complex field geometries, especially where the domain extends into unbounded soil regions. This integrated DRBEM-FEM model provides a reliable and computationally efficient tool for optimizing irrigation system design and evaluating infiltration rates under variable soil and climatic conditions.Keywords: water infiltration, agricultural irrigation, Hybrid DRBEM-FEM method, Irrigation modeling, Soil moisture simulation.