FUNDAMENTAL EXPERIMENTS ON RIVERBED COLONIZATION PROCESS OF Egeria densa

Abstract

 In recent years, the alien aquatic weed Egeria densa has been founded n the river mainstream, Chugoku district. The inhabitation process of Egeria densa has been revealed in several previous studies. On the contray, there is not enough investigation on the riverbed colonization process. We conducted the flume experimnts to understand the relation between the initial growth of the fragment traped on gravel riverbed and three hydraulic conditions: constant low velocity, constant high velocity and fluctuating velocity.

 The result revealed that the sprouts and roots of Egeria densa increase in the conditions of constant high and low velocity, while the fragment of Egeria densa tends to die without the growth of the sprouts and roots in the conditions of fluctuating velocity.