Algorithm is described for modeling of flow lines from a gridded elevation model. The algorithm is based on looking for the optimal way for a step-by-step downward moving. Vector (flow) lines are especially relevant in geomorphological studies of polar regions. Joint analysis of subglacial topography and ice flow lines allows revealing the areas of occurrence of glacial erosion. Vector (flow) lines provide an important mathematical tool in the development of evolutionary models of continental denudation. A number of examples arc provided from one of the regions in the East Antarctica.