A REPORT ON THE METHOD TO INVESTIGATE THE FLAKING EFFECTS OF ATTACHED ALGAE BY THE FLUSHING DISCHARGE OF HAIZUKA DAM

Abstract

We tried a new method to investigate the flaking effect of attached algae by the flash discharge, in Haizuka dam.

Though there is a method of examining the amount of the change of attached algae before and after discharge as a general search procedure of the flaking effect. However, we tried the method of clarifying the flaking effect of attached algae from the flux of the photosynthetic pigment that flowed in the river for the discharge period in Haizuka dam.

As a result, we were able to clarify the following facts that were not able to be understood by the current methods.

・The gross weight of attached algae that flaked off in the downstream river, (including the amount that originates in withered attached algae that piled up in riverbed) was clarified.

・The section where the flaking effect was large and the section where the subsidence was caused were clarified.

・The relation between the amount of the section flaking off and flowing quantity was able to be understood in the time series. And it was able to be confirmed that flaking off was advanced when flowing quantity was rapidly increased.