Hydrological indicators of the riverbed incision along the free-flowing Danube River reach from Budapest to Slankamen relevant for the lateral connectivity between the river channel and floodplains

Abstract

Hydrological regime plays a primary role in the sustainable management of floodplains, as floodplain ecosystem dynamics and balance are largely dependent on the dynamics of the flow regime of rivers. In the 1980’s a drying process of floodplains on the lower Danube reach in Hungary became evident while in the 2000s continuous unimpeded water supply of the main canal network in the Danube-Tisza-Danube water supply and drainage canal system became an alarming problem. In view of these problems, the present analysis aims at: 1) recognising hydrological indicators of the incision and/or aggradation of the riverbed, 2) estimating the extent of these processes and the rate of change of the riverbed in time based on these indicators, as well as 3) estimating possible consequent changes in the frequency of extremities. The study has shown that the lateral connectivity is at risk along the whole reach as the deepening of the riverbed still continues and according to some parameters (e.g. the gradient of decrease of mean water levels) is even increasing.