Abstract

This study investigates the hydrodynamic behavior of Lake Sahambavy, located in Fianarantsoa, Madagascar, using the IRIC (International River Interface Cooperative) numerical simulation software. A two-dimensional hydrodynamic model was developed by integrating geo-hydrological, climatic, and land-use data to analyze water level variations, flow dynamics, and morphological processes within the lake.
The model incorporates transient boundary conditions, hydraulic roughness parameters, and stable numerical schemes. Simulation results reveal pronounced spatial variability in velocity, water depth, and free-surface elevation, controlled by bed topography and asymmetric channel geometry. Nonlinear hydrodynamic behavior between upstream and downstream areas highlights zones of flow concentration sensitive to erosion and sedimentation. Overall, the study confirms the relevance of IRIC as a decision-support tool for sustainable water resource management and hydrological risk mitigation in Malagasy lacustrine systems.