Local flood hazards assessed from channel morphometry along the Tisza River in Hungary

A large-scale flood-control project (the so-called Amended Vásárhelyi Plan) is being implemented along the Hungarian section of the Tisza River. A detailed assessment of the flood hazards along various reaches of the river is needed. In addition to hydrological, sedimentological and geoecological investigations, the contributions from geomorphologists may also be of significance for the estimation of the flood hazard through— the identification of floodplain sections under the strongest human impact;— revealing the extent of modification of channel parameters by channelization;— surveying channel adjustment tendencies;— assisting the allocation of the planned flood reservoirs.Although floods heavily affected the Tisza system even before channelization, a fundamental assumption of the paper is that the restabilization of the low-gradient meandering river channel exerts a beneficial influence on water and sediment transport and reduces the flood hazard. Relationships between flood hazards and channel morphometry (meander belt width and sinuosity) are sought section by section to be employed in flood-control (primarily flood-reservoir) planning. The confinement of the channel, expressed by the distance between dykes is found to be a decisive parameter and has to be taken into account in flood-control strategies, while the interpretation of sinuosity is more complicated. Although no morphometric study in itself is sufficient to comprehensively characterize flood hazards, a morphometric index may significantly contribute to the hydrological assessment of the development and passage of flood waves.