Bubble water depth measuring method and system thereof

A water depth measuring method comprises steps of making a bundle of reference water column pressure measuring tubes of a U character form of the number of n>=2 at a same length with a water depth measuring tube in order to compensate for a total error SIGMADELTAx of a water depth measurement; filling an amount of water into the reference water column pressure measuring tubes to form water columns ho1, ho2, . . . hon therein; measuring the water pressure in the reference water column pressure measuring tube by a pressure transducer before measuring a water depth; subtracting previously known water column pressure gammahoi and gammahoj derived from the measured water pressure values Pmi, and Pmj to calculate total errors SIGMADELTAi and SIGMADELTAj; calculating a total error SIGMADELTAx based on the total errors SIGMADELTAi and SIGMADELTAj, in which the total error SIGMADELTAx was generated upon measuring of the bubble generating pressure Pmx in the water column pressure measuring tubes; subtracting the total error SIGMADELTAx from the bubble generating pressure Pmx, dividing the calculated water column pressures by the water column pressure gammahoi(j) in the reference water column pressure measuring tube having most approximate value thereto and multiplying the re-calculated value by the water column pressure hoi(j) thereby to measure a water depth in a higher accuracy, in which the water depth measuring tube has a length corresponding to a water depth, the reference water column pressure measuring tubes has the same inner diameter as that of the water depth measuring tube coupled therewith, in which a diaphragm is connected through an electromagnetic valve to one tube of the reference water column pressure measuring tube to adjust the speed of the compressed gas from a buffer tank to be supplied to the reference water column pressure measuring tubes, a transparent container is connected to the other tube of the reference water column pressure measuring tubes to measure an amount of water therein and check it, periodically, and includes a nipper for supplementing water reduced due to the evaporation, a tube is directly mounted above the transparent container and has the same inner diameter as that of the reference water column pressure measuring tubes and a length portion, on the surface of which scales are formed, a thin film tube is made of rubber and directed to the upper portion of the tube to be expanded by a gas pressure, and a manual valve connecte