Abstract
Turbidity is optical scattering intensity to suspended sediment. In this study, the influence of particle size on turbidity output was examined in laboratory, and the instructions for using turbidity meter in the field was discussed based on observation data. As particle size grow bigger, turbidity decrease for same SS concentration (SSC). The optical scattering intensity can be obtained up to the size of 0.42mm. SSC can be calculated by turbidity and particle size accurately. When turbidity is monitored in actual water area, SSC is converted from only turbidity using correlation curve between SSC and turbidity, because particle size distributions are not change significantly in the same station. It is desired to develop the new type backscatterance nephelometer which can measure not only the turbidity but also the particle size.
