NIRE Annual Report 1997

NIRE Annual Report

1997

Water Quality Change Processes of Groundwater in an Artificial Seashore

Objectives: In order to clarify the quality of groundwater at the Kasai artificial seashore located at the northern end of Tokyo Bay, the observations were made in September, 1992 and February, 1993. In this research, the quality of the groundwater in sand layers at tidal zones and the quality of shore edge seawater of the artificial coast were measured, and the local change in the quality of groundwater was grasped. According to these results, it was examined what effect the water quality in the front sea area is subjected to the environmental effect of the artificial beach.

Results: The results obtained by the observation of the groundwater quality in Kasai artificial seashore are shown in Fig.1. Besides, the states of the flow of groundwater and the change processes of water quality in the same region are shown schematically in Fig.2.; According to the above, the following matters have become clear. In the backshore of Kasai artificial seashore, the fresh water source having high COD concentration exists, and in its process of flowing down slowly toward sea, it exerts effect to the upper layer of mid-tide zone groundwater quality. This phenomena were able to be guessed from the vertical distribution of groundwater at the center of the tidal zone.; In the mid-tide zones, the clear difference of groundwater quality was observed between the upper layer of sediment (under 10~20 cm) and the lower layer beneath it (under 20~50 cm). It is presumed that the groundwater in the lower layer has low chlorinity from the backshore.

1)	Measurement of the water quality change processes of groundwater in an artificial seashore. Journal of NIRE, 5:339-348, 1996

National Institute for Resources and Environment