Use of a 1D hydrodynamic model for assessing phytoplankton dynamics in Tisza River (Hungary)

Our analysis was part of a comprehensive research study that focused on algae dynamics and aimed to estimate the distribution of net growth rate ( details in IsTV ÁNOVICS & HoNTI 2008.). The project was based on the high frequency, on-line measurement of longitudinal phytoplankton pattems carried out on Tisza River. Water parcels measured multiple times provided information about the variation of the algae biomasses associated to them. Growth rates were estimated by using travel times elapsed between the measurements (HoNTI et al. 2008), which required knowing the river's unsteady velocity field. Thus the purpose of this study was to provide hydraulic input, namely velocity data, for the analysis o f field observations. Considering the long and narrow spatial extents of the observed region, the 1D approach was sufficient. The Saint Venant equations were solved numerically to provide velocity pattems and to derive travel times. Results were evaluated on the basis of sediment modeling.