The published studies related to hydrodynamic, hydrologic and pollutant loads especially in the fields of rivers and estuaries were briefly summarized. Salinity in the upper and the bottom layers, and flow rate at the monitoring point near the river mouth of the Ebigawa River, Chiba Prefecture, Japan, were analyzed with tidal level fluctuation at the Chiba Port as a preliminary study for the development of a hydrodynamic and water quality model in the estuary segment of the Ebigawa River. Contour lines and anthropogenic water contribution to water flow were analyzed. Defining contour line patterns could enhance understanding of the flow and salinity patterns in the estuarine zone of the river. It was qualitatively confirmed that the tidal level fluctuation, fresh water inflow, and anthropogenic water influenced the salinity and flow rate at the monitoring point.