The present paper describes conceptual design of a deep ocean water upwelling structure that is used for enhancement of ocean nutrient aiming at development of fisheries. The conceptual design is based on feasible design studies of a structure that satisfies principal requirements of upwelling flow rate and depth of sea. The feasibility studies leads to propose a structure concept that is composed of a submerged vessel equipped with power supply, pumps and a riser of deep ocean water, and the system is moored on seabed. The design of the system is evaluated from extensive aspects such as engineering reliability, operational and economical points of" view.
Innovative projects for developing new fishing grounds are being promoted by The Marino-Forum 21 (MF2l), an extra-departmental body of The Fisheries Agency of Japan. One of the feasible concepts will be a methodology to enhance ocean nutrient by discharging deep ocean water (DOW) with rich nutrient into photic zone by applying an upwelling device moored in the ocean, that leads to make the seawater of euphotic zone fertile with phytoplankton. This device can be called as the Ocean Nutrient Enhancer (ONE). Aiming at realization of this concept, MF21 has organized a consortium that consists of two groups for investigating the effect of ocean nutrient and developing the equipment. The project has started from feasibility studies including field surveys of the geographical and social conditions at a location of setting up and the structural design of the device from engineering reliability, operational and economical points of view. On the other hand, applying mechanics of density current in stratified water, a concept machine for upwelling a stratified water area was proposed and a design of Density Current Generator was presented (Ouchi et al 1998).
