Appropriate evaluation of groundwater flow channel is very important in terms of development and maintenance of effective groundwater resources, conducting safe and economical construction work, and environment conservation of soil and groundwater pollution. In this study, by comprehensively analyzing hydrological geological data such as topography, boring, groundwater level and water quality, it was found that a highly permeable sand gravel layer including light brown gravel which is located beneath coastal area may have been formed by a debris flow．And this gravel layer penetrated the bar and reached the sea, it have acted as main groundwater flow channel of the coastal area. It is important to evaluate hydrogeological structure considering geomorphic evolution history and sediment characteristics because groundwater flow channel is formed by single local geolo gical events.