抄録
To grasp the temporal change of hydraulic phenomena in tidal area of the Uchikawa River during saltwater intrusion into the river, a long-term observation was carried out using the ADCP. As a result, detailed vertical velocity distributions of two-layer flows with salt-wedge type in tidal area of the Uchikawa River were observed. It was found that saline water with weakly-mixed type made intrusions into the Uchikawa River regardless of seasonal and/or tidal effects. Especially, time series of flow velocity had periodicities during salinity intrusion. Furthermore, flows in both upper and lower layers were laminar flow and showed Fd1≈0.4 in the front part of saline wedge, and then turbulent flow zone within Fd1≤0.4, 104≤Re1,2≤105 was observed when fresh and saline two layers had been stable. It can be inferred from previous studies that it is possible to estimate the interfacial resistance coefficient fi using the proposed Iwasaki number φ function for the tidal area of the Uchikawa River.
