WRRCTR No.152 Stream-Water Storage in the Ocean by Using an Impermeable Membrane

Abstract

The conceptual feasibility of storing fresh water in the ocean was investigated using a plastic membrane as the reservoir liner. In the initial phase, two physical hydraulic models were constructed to test the concept. The first was a water-filled, glass-sided box to observe the movement and reaction of the membrane to various simulated effects of currents, waves, and sediment deposition. The second was a 1:400-scale model (6.7 x 6.1 m) of West Loch, Pearl Harbor (a potential field application site), with 1:24 vertical exaggeration for similitude. The curtain method was used because it can enclose a large water body. The effect of wind, waves, tides, and currents on the curtain were simulated and the reactions observed. Although modeling is a useful tool for investigating initial concepts, its direct field application is limited because of scaling. Actual field testing on an initial pilot-stage basis constituted the second phase. Curtains, floating reservoirs, and bags were constructed of polyethylene sheets and deployed. All worked well after modifications were made following initial testing. The bag is the easiest to deploy because it is prefabricated and ready for use. No field attachment of floats and anchors is necessary, as for curtains or floating reservoirs; however, the latter two have certain characteristic advantages which may override this difficulty. Based on this experimental experience, the concept of membrane water-storage appears feasible and further development work leading to operational equipment seems justified. Selection of suitable membrane material is one of the key factors to be explored, along with the effects of weathering and biota. Quiescent waters are essential to the success of this concept.