Mathematical modelling of flow dynamics of the urban river Nevezis in Kedainiai

Abstract

The dynamics of flow velocities and water level in the Nevėžis River in Kėdainiai was estimated by applying a hydraulic-mathematical model DELTA. It was established that there were no conditions for a non-desirable riverbed siltation. During the dry season flow velocity in the examined section does not exceed 0.5 m/s. When the discharge Q=70 m3/s affects the formation of the riverbed, the flow velocity reaches 1.2–1.3 m/s and accumulated bed sediments are washed away. A twometers high dam near Skongalis does not stimulate bed silting too, because it is not high and it can barely influence bed formation processes or reduce the riverside overgrowth. When the water level is low and the flow velocity is small (0.1 m/s), the water in the river is only slightly turbid (turbidity is 2–6 mg/l). In order to improve the esthetical view of the river, it is advisable to regulate the riverbed by reducing the river width at its wide sections up to 30 m.