EFEECTS OF HYDRAULIC FACTORS ON BIOMASS ALONG BIOFILM FORMATION IN GRAVEL BED RIVER

Abstract

Temporal and spatial variations in the biomass of the biofilm, which were constituted of algae, bacteria and fungi, with benthic algae the dominant components growing on a cobble submerged in running water were investigated every day for a period of 40 days, from January 28, 2004 to February 5, 2005 in the Shirakawa River. Using the logistic model, temporal variations of biomass was analyzed in the periphyton developed in three current regimes different in flow velocity and accumulated height of suspended sediment. The intrinsic growth rate and carrying capacities were estimated by the linear relationship between the algal growth rate and biomass. The results showed that the carrying capacity was maximized in the riffle without accumulated fine sediment and at the top of cobble.