A Fundamental Study on the Behaviour of Submarine Groundwater Discharged into Coastal Sea

Abstract

ABSTRACT : It has been considered that most of the terrestrial water and contained materials are supplied into the ocean through the rivers. However, recent studies show that the submarine groundwater discharge (SGD) is also significant as the route of water and materials from the land to the ocean. In order to evaluate the influences of SGD on the coastal water environment, it is important to investigate the amount of SGD flux into the sea as well as the behaviour of discharged water and materials in the coastal water. In the present study, the total SGD flux is estimated by the budget analysis of the target sea area, in which a parameter for water exchange between the coastal zone and the ocean is calculated by means of a numerical simulation of water movement and a dynamic budget model. The behaviour of discharged groundwater is also investigated by means of hydraulic experiments and numerical simulations using non-hydrostatic model. It is found that the early-stage behaviour of the discharged submarine groundwater as buoyant plume could be categorized into three types due to the ratio of discharge velocity to the background horizontal current velocity.