Investigation of the natural morphodynamic state of a Tisza river section in Hungary

Our research focused on the river regulation in Hungary in the 19th century, as it resulted in significant morphodynamic changes. The Tisza River was significantly meandering in its contemporary state and the regulations were used to cut through these meanders. The main question is what bank geometry and flow conditions were formed in the natural state of the river, before the regulation works?

In our research, we wanted to study a selected section of the Hungarian Tisza, where a detailed literature search revealed that there was not enough data on the contemporary condition to suitably describe the natural morphology. This led to the need to develop a procedure that would be able to map the pre-regulation condition in a way. To this end, a novel method for estimating the geometry of the riverbed was used. pyRiverbed is a tool that estimates the bankfull bed geometry based on the river's centerline and the average channel depth and width. Using the 'synthetic' geometry produced in this way, we were able to calculate flow characteristics (e.g. typical flow velocity and bed shear stress, reach-averaged bed resistance) for the pre- and post-regulation conditions using 2D flow models and compare these parameters.

Our research also aims to show the importance of studying the sediment budget of a river and its role in the variation of riverbed geometry. We believe that such a method could play a major role in future regulatory work and could also help in the preparation of regulatory plans.