The central problem of a combined analysis of digital terrain models (DTMs) and other landscape data is determination of a DTM grid size (w) providing a correct study of relationships between topographic variables and landscape properties. Generally, an ‘adequate’wis determined by an expert estimate, and solutions are largely subjective. We developed an experimental statistical method to determine an adequatewfor DTMs applied to landscape studies. The method includes the following steps: (a) derivation of a DTM set using a series ofwi, (b) performance of a correlation analysis of data on a landscape property and a topographic variable estimated with variouswi, (c) plotting of correlation coefficients obtained versusw, and (d) determination of smoothed plot portions indicating intervals of an adequatew. We applied the method developed to study the ifluence of topography on the spatial distribution of soil moisture (M) at a micro-scale. We investigated the dependence ofMon gradient (G), horizontal (kh), vertical (kv), and mean (H) landsurface curvatures. For DTM derivation, we used 13 values ofwifrom 1 to 7m. An interval of adequatewiforMfalls between 2.25 and 3.25m in the given terrain conditions. In absolute magnitudes, correlation coefficients are largest within this interval; correlation coefficients ofMwithG,kh,kvandHare 0.28, 0.52, 0.50 and 0.60, respectively, forw= 3m. The results obtained demonstrate that the method actually works to identify an adequatewat a micro-scale. The method developed allows estimation of an adequate area of landform which ‘realise’ a topographic control of landscape properties.