Impact of different rainfall events on overland flow using a 2D hydrodynamical model on a steep-sloped watershed

 

Gergely Ámon¹, and Katalin Bene²

 

^1,2National Laboratory for Water Science and Water Security, Széchenyi István University, Department of Transport Infrastructure and Water Resources Engineering, Egyetem square 1., H-9026 Győr, Hungary

 

Flash floods and low-flow events often severely impact small, steep watersheds. Water resources engineers need to understand and prepare for these events. On small, steep-sloped watersheds, meteorological and watershed characteristics influence the behaviour of the overland flow. In this research, we applied different precipitation events in time and intensity

 on the watershed to determine the impact on outflow characteristics.

The Hidegvíz-valley watershed on the north-western side of Hungary, a well-measured and instrumented experimental watershed, was selected for surface flow modelling. A 2D hydrodynamical model was developed and calibrated on a measured rainfall-runoff time series. Two measured rainfall events and triangular design rainfalls with different return periods were applied to the calibrated model to determine the impact on surface runoff attributes. Peak outflow, runoff ratio and runoff volume were selected to describe outflow characteristics. The results show that the peak flow at one rainfall event is much greater than at the other rainfall events. The volume of a rainfall event increases for longer-duration events. After certain rainfall events, the runoff ratio and runoff volume did not change much.

The research will help to better understand runoff processes due to different rainfall events and durations and help to improve the design approach for flood and drought protection.

Keywords: numerical modelling, hydrodynamics, overland flow, watershed model

 

The research is carried out within the framework of the Széchenyi Plan Plus program with the support of the RRF 2.3.1 21 2022. 00008 project.