Vol. 128, No. 4 * Pages 399–496 * October - December 2024

The study aims to examine the relation between rainfall intensities and times of concentration based on rainfall-runoff modeling using the recently developed features of the Hydrologic Engeneering Center – Hydrologic Modeling System (HEC-HMS) modeling software. The time of concentration is generally considered a constant characteristic of a catchment. However, various publications have shown that response time is a dynamic property and a function of rainfall intensity. Model simulations were performed to gain more insight into the relationship mentioned. The applicability of the dynamic time of concentration was examined with the help of a recent version of the HEC-HMS software that can interpret the dynamic relationship between time of concentration and rainfall intensity. The models were built for characteristic and dynamic cases. In the characteristic case, the time of concentration values of the catchments were calculated using the commonly applied Wisnovszky empirical equation, while in the dynamic case, the applicability of the rainfall intensity, i.e., the time of concentration function, was examined.  The applicability of the new HEC-HMS feature was reviewed, and the relationship between the time of concentration and rainfall intensity was confirmed. The dynamic approach improved the models’ performance, especially where the Wisnovszky equation yields an inadequate estimation of the time of concentration based on the results.