Bubble water depth measuring method and system thereof

A bubble water depth measuring method of finding a water column pressure of a water depth measuring tube with a bubble pressure to measure a water depth comprising steps of:

• disposing reference water column pressure measuring tubes of a U shape of the number of n≧2 at a same length with the water depth measuring tube;
• filling an amount of water into the reference water column pressure measuring tubes h01, h02, . . . h0n to form a water column therein;
• supplying compressed gas to the reference water column pressure measuring tubes for a short time period from one tube thereof and raising up along the other tube thereof to form water column pressures yh01, yh02, . . . γh0n;
• memorizing the water column pressure Pmx that the water column pressures of the water depth measuring tube are measured with the bubble generating pressure;
• measuring gas pressures Pm1, and Pm2, for maintaining the water column pressures yh01 and yh02 at the reference water column pressure measuring tubes corresponding to sections hoi˜hoj positioned under the water column pressure Pmx;
• calculating total errors ΣΔi and ΣΔj in the water column pressures;
• calculating a total error ΣΔx based on the total errors ΣΔi and ΣΔj as follows;
• ΣΔi=Pmi−γhoi, ΣΔj=Pmj−γhoj
• ΣΔx=ΣΔi+((ΣΔj−ΣΔi/Pmj−Pmi)×(Pmx−Pmi))
• and, calculating a water depth hx as follows;
• hx=((Pmx−ΣΔx)/(Pmx(j)−ΣΔi(j))×hoi(j)
• wherein, among Pmi(j) and Hoi(j) mean Pmi or Pmj and hoi or hoj, the water column pressure closest to Pmx is selected.