Increasing the Efficiency of the Sacramento Model on Event Basis in a Mountainous River Basin

Abstract

An evaluation of the Sacramento Soil Moisture Accounting (SAC-SMA) model was conducted to be used in flood event simulations with datasets at a time step up to one hour. The SAC-SMA model is a complex conceptual model which integrates two soil zones, the upper and lower zone, in order to provide current soil moisture conditions and generated streamflow. However, in flood events, where time intervals are small, the generated flood hydrograph is usually the product of only the upper soil layer runoff generation mechanism while the lower zone and baseflow have little impact. In this context, a modified version of the original SAC-SMA model was introduced, where only the upper zone processes are kept in order to reduce the parameter count and the overall model uncertainty involved, and a comparison was made against the original model output. The two models were calibrated and validated for a series of flood events occurred at the Karitaina basin of the Alfeios river, located in southern Greece. The results show that both model versions were able to reproduce the observed runoff with success. The simplified model showed high consistency with the original model in all cases, which is an obvious improvement to the original model, since it provided results of equal quality, while lowering significantly the total parameter count and the computing time. This contributes against the overall model generated uncertainty which is crucial for real-time data processing applications and flood forecasting systems. • Presentation of the SAC-SMA model concept, variables, parameters and flowchart. • Introduction of a modified – simplified version of the original SAC-SMA model to be used for event-based rainfall runoff applications. • Calibration and validation of the SAC-SMA using fine temporal scale datasets in a mountainous basin in Greece.