Field Observation and Water Budget Analysis of the Coast of Osaka Bay, Japan

A coastal sea is affected by directly material load from the land area. Especially the northeastern part of Osaka Bay which adjoins the urban area, Osaka, Kobe and so on is eutrophic sea, because there are much material loading and a few seawater exchanges due to the reclamation and the breakwater. Omae beach is natural beach and is located in the Shuku River mouth in Nishinomiya City. Groundwater in the seaside part of Nishinomiya City is abundant. Therefore, it is considered that the submarine fresh groundwater is discharged from the sea bottom of the coastal zone of the Omae beach. In this study, we will discuss the physical structure of the area based on the marine observation data. The stratification is developed and the horizontal flow from the southern side dominates in the area. Water exchange by flow dominates in the area. SFG discharge is 53% of the discharge of the Shuku River. But TP discharge from SFG is 7.6 times of the TP discharge from the Shuku Rive. Effect of the SFG to the whole of the area may be small. But it will have the influence to the inter-tidal zone. The bio-chemical distribution is affected by the physical structure.