Stream Level Stabilization by Algae of the Genus Cladophora

Abstract

Abstract Investigations in the Pryský brook experimental catchment revealed that the vegetation of the stream channel stabilizes water level depth in the measured profile. The explored brook has been heavily overgrown by algae of the genus Cladophora due to a strong pollution by nitrates. It seems that if the algae average length exceeds the midsize of the stones paving the bed (ca. 30 ± 7 cm in diameter, escribed circle to pentagon or heptagon), the water level stagnates in the flowrate range of 60–180 l s−1. This totally blocks the streamflow daily oscillation (in summer months in a purely stone bed reaching up to 15%, along with tidal phenomena). The article analyzes one of possible explanations of this effect due to the dependence of the algae thickness layer modifying the channel bed cross-section on the speed of flowing water.