OXYFLUX, an innovative wave-driven device for the oxygenation of deep layers in coastal areas: A physical investigation

• Wave-driven device (and its mechanism) to counteract lack of oxygen at the bottom sea, called OXYFLUX, is presented;
• 45 regular wave states are generated in a wave flume in order to analyze the OXYFLUX performance;
• Performance of two mooring systems is investigated;
• Heave and horizontal rigid displacements of the OXYFLUX are measured by means of computer vision technique;
• Estimation of total pumped volume of water and oxygen is proposed for an application along the Northern Adriatic Coasts.

Coastal areas for anthropic zones are vital economic hubs for tourism, fisheries and recreational activities. These are just some of the businesses which develop and grow many parts of the world. In terms of water quality, the growth of economy, along with the acceleration of climate change makes it necessary for sustainable coastal defense plans. No other environmental variable of such ecological importance to estuarine and coastal marine ecosystems around the world has changed so drastically, in such a short period of time, as dissolved oxygen in coastal waters. This paper specifically addresses the use of a new floating device called OXYFLUX, (devoid of electro-mechanical sections), as an innovative approach to altering water quality parameters with the aim of increasing the concentration of dissolved oxygen in the underwater areas near the bottom. This is based on laboratory results. The experiments were carried out on a device in 1:16 scale in wave flume at University of Bologna.OXYFLUX's functionality is based on floater's capacity to collect incoming waves into a reservoir that floats on the sea surface. Collected water yields a higher hydraulic head in the reservoir, which in turn induces a downward water flux inside the device body. The dynamic response of the device, and it’s pumping capacity are assessed under a variety of wave conditions by changing wave steepness. Experiments allow a first outline of design recommendations for these kinds of devices. At the end of the paper such guidelines are applied to Northern Adriatic coast conditions.