This paper presents a method of directed information transmission for wireless sensors network based on digital terrain model. Using network of irregular triangles and Delaunay's triangulation algorithm a drainage function is constructed that covers all routing paths from nodes to the base station. Drainage function describes a set of points in 3D space and is a composition of several surfaces. There are two basic surfaces, first is fixed and related to the natural network topology features, second is variable and represents energy cost of a communication activity. Additional surfaces, that enable to model different kind of message routing strategies, are proposed for future work. Our proposal allows to shape the drainage function through modification of collision, subordination and tolerance coefficients that upheaval, lower and draw aside the surface respectively, leading to different communication activities.