Bed sediment dynamics in the Gabčíkovo-Topoľníky channel: The three-decade case study

This paper was focused to find out the impact of silting of Gabčíkovo-Topoľníky channel on the flow conditions at this channel.There were performed the detailed field measurements of bed sediment thicknesses along the Gabčíkovo-Topoľníky since the year 1993 to 2023.Based on the calculation of the values of the average thickness of the bed sediments, there was determined the longitudinal distribution of the bed sediments along the Gabčíkovo-Topoľníky channel, the percentage of silting of the flow area in this channel and the values of the volumes of bed sediments in this channel during the monitored period, which was the main objective and the reasons of this research.This paper relates to evaluation of results from the field measurements at Gabčíkovo-Topoľníky channel during whole monitored period since the year 1993 to 2023, especially compares the results from measurements between the year 1993 and 2023.Gabčíkovo-Topoľníky channel is one from three main channels of Žitný Ostrov (Rye Island) channel network.The area of Žitný Ostrov (ŽO) is flat land and the velocities in all channels of channel network are very slow.The occurrence of small velocities is considered for main reason of sediment`s aggradation at channel bed.The flow profile of channels is reduced by increased thickness of bed sediments.Consequently, the permanent sedimentation process is unfavourably changing not only the cross-section of channel, but also its longitudinal profile.The channel´s capacity is therefore significantly reduced, e. g. the channel conveys much lower flow as a result of obstruction, lowering the efficiency at channel performance.The volume of sediments is also growing.Bed sediments, their thickness and texture have the important impact to interaction between surface water in channels of ŽO network and groundwater in its surroundings.The results of these measurements are summed up in all tables and figures of this paper and their comparison indicates the growing trend of longitudinal silting of this channel and the volume quantity of bed sediments during the observed period -30 years.