Level account of a condition of groundwaters in drained massifs of polder systems with an allowance for drain

The effective algorithm of numerical level account of a condition of groundwater with allowance for drainage systems is resulted. The complication of realization of the indicated algorithm of a numerical solution is encompassed in a share solution of a bivariate Bassinet's equation and differential equation of carrying of water in drainage ducts (DD), as in a part of creation of stable and costeffective difference schemes, and coordination them on boundary conditions on an outline of interaction between water lines in conducting channels and ground-water levels of a drained massif.