FIELD: drainage and irrigation. SUBSTANCE: method determining critical depth of occurrence of underground waters includes determination of depth of occurrence of underground waters and layer-by-layer sampling of soils, qualitative analysis of aqueous extracts of soil for content of chlorides and readily soluble sulfates by first emergence of these salts in aqueous extracts of soil at moment of sampling. Qualitative analysis to find readily soluble carbonates and quantitative determination of chlorides, readily soluble sulfates and carbonates as result of observations of many years is conducted additionally. Then salt profile of soil with underlining of upper boundary of horizontal many-year capillary rise of maximum content of salts is plotted. Later critical depth is computed by difference of occurrence of underground waters and upper boundary of horizontal many-year capillary rise of maximum content of chlorides, readily soluble sulfates and carbonates. EFFECT: increased accuracy of computation for any types of soils. 2 dwg
