EXPERIENCES IN APPLICATION OF HEC-RAS MODEL UNDER CIRCUMSTANCES OF FLOOD WAVES

Abstract

The very varied flow regime of River Tisza is characterized by repeated floods with gradually increasing and sometimes very high peak water levels and by frequent, long-lasting low flows. The main causes of these characteristics are: the shape of drainage basin; the discharge of tributary streams related to the one of the main channel; the high sediment transport; the low slope of the low-land reach and the trained low-flow and high-flow river channel. The present length of R. Tisza is 945.8 km and its drainage basin is 157 200 km². According to discharge measurements of the recent decades, the maximum discharge of Tisza River at section Tivadar (705.7 rkm) exceeds 4 000 m³/s, in the middle reach between Szolnok and Kisköre: 2 600-2 900 m³/s and in the lower reach, at section Szeged (173.6 rkm) above 4 000 m³/s.