Using empirical equations and SWAT+ modeling to estimate sediment loads in the Iponan River, Misamis Oriental, Philippines

ABSTRACT Sedimentation is a process in river systems whereby sediment is mobilized and transported eroded material is deposited, impacting water resources and the stability of ecosystems. The Iponan River is crucial for sustaining local ecosystems, yet it faces increasing sedimentation due to intensified human activities, population growth, and extreme weather events. The increase in sediment deposition will result in a higher likelihood of severe river floods. Therefore, this study estimated the sediment loads in the Iponan River using empirical equations and the SWAT+ model. The comparative analysis revealed that among the evaluated approaches, the Einstein equation provided the most accurate estimates for bedload transport, showing close agreement with observed data. Although it slightly overestimated sediment loads during low-flow conditions, its accuracy improved as sediment transport increased. The SWAT+ model, a process-based hydrologic model, effectively simulated river discharge and predicted total sediment load, producing strong agreement between predicted and observed values (NSE = 0.968; PBIAS = –4.241 for river flow, and NSE = 0.932; PBIAS = –4.546 for sediment load). These results confirm the Einstein equation as the best method for bedload estimation and the SWAT+ model as a reliable predictive tool for simulating total sediment yield and river discharge.