According to the parameters from Ruth filtration equation,factors affecting the filtering efficiency of the vertical disc vacuum filter are analyzed and the effect of submerge ratio on filtering efficiency is discussed in detail in the paper.

Study on immersion area of the Liaofang hydranlic engineering project;

Xixiayuan reservoir,a plain reservoir, will bring some immersion to the areas of the lower reaches of the dam, the dam with or without antiseepage measures will create different effects on immersion of lower reaches of the river.

The second variation formula of vertical energy functional for a submersion between Riemannian manifolds is calculated with a simple and direct manner.

As the water level in the reservoir of Chaozhou water supply project is generally higher than ground surfaces on both banks when the reservoir is filled up,the city and the farmland along the riversides may be immersed in groundwater.

The important technical problem of submergence evaluation for the right bank of down stream of the subsidiary dam in Nierji irrigation works was solved.

Aiming at the irresolvable limitation of the infiltration recharge and evaporation from the upper boundaries of the submergence prediction, this paper has established a mathematical model for transient flow based on groundwater simulation software Visual Modflow, which takes account the conditions of recharge and evaporation for the analysis of effect of submergence on the nearby farmland.