Report on the Environmental Conditions, Joint Shapes and Pipe Gradient of the Asian Clams in Pipelines

Abstract

Clogging of terminal faucets by Asian clams has been reported in the Miyagawa Irrigation Network, Mie prefecture. A previous research reported that the Asian clams inhabited the hollow of the pipe joint in the in-pipe survey of Government-managed No.1 trunk channel of the Miyagawa Irrigation Network. In this study, we conducted an in-pipe survey at Government-managed No.2 trunk channel, which had few clogging reports and different conditions such as flow velocity and pipe diameter, and analyzed the inhabiting condition of Asian clams. The results were compared with the previous research. The differences in the population due to the pipe gradient and joint shape of the pipeline were examined. As a result, regardless of the number of damage reports, it was confirmed that Asian clams were inhabiting in high density of about 6,000 clams/m² at joints. It was found that Asian clams are hard to accumulate at the joint of downstream socket and where the pipe gradient exceeds 10 degrees.