Dynamic saturation area and water balance modelling of karstic basins

Abstract Water balance models are known as major tools for simulation of basin‐wide water cycle components. Considering the complexity of the runoff generation processes in karstic basins, it is crucial to bring the model processes closer to the physical reality of karstic springs and their contribution to runoff formation. One of the challenges in basin‐scale modelling of karstic basins is that the basin response to precipitation is highly influenced by the soil saturation condition and its seasonal variability. One way to address this challenge is to include a dynamic structure for the water balance model. In this research, the structure of SAM‐KARST water balance model for estimation of monthly streamflows in the outlet of karst basins was presented. Moreover, to better simulate the basin response fluctuations in different seasons, the SAM dyn ‐KARST model with a dynamic storage structure was introduced and developed. The results of the SAM dyn ‐KARST model were compared with the saturation area model (SAM) and SAM‐KARST models for the Shapur river basin in southwest of Iran. The results confirmed the importance of considering larger saturation storage in the karst basins. The case study results also showed that SAM dyn ‐KARST outperformed SAM‐KARST model and provided higher accuracy in estimating seasonal variations of surface streamflows at the basin outlet.