Bed Topography and Discharge Measurements in the Świderskie Islands Nature Reserve, River Vistula, Poland

Abstract

Field tests were carried out at a section of the River Vistula located within the boundaries of the Świderskie Islands nature reserve in order to analyse bathymetric changes at different discharge values during the period of 2012–2014. The paper shows that the dynamics and transport of sand-waves and sandbanks strongly influence the bathymetry of the riverbed at the selected cross-sections. Moreover, the impact of groynes on the bed topography is briefly discussed. Discharge measurements completed with the use of an acoustic Doppler current profiler (ADCP RiverSurveyor S5, SonTek) are also presented. Results support the values given by the Institute of Meteorology and Water Management (IMGW) at the gauging station in Gusin (461 km from the source) solely for the mean water levels. It is shown that the differences between measured values and values given by IMGW of the flow discharge ranged from 3 to 30 % of measuring values depending on the water level and discharge itself. The findings of this study may provide essential tutorial material for education in hydrology, civil engineering and environmental hydraulics as they emphasize large uncertainties inherent in hydrological modelling resulting from high dynamics of the bedload transport process.