Violent changes in water regime require quicker and quicker information relating to flood
threats. Polish monitoring system is insufficient, in particular in the case of small and average
drainage areas. This creates the necessity of searching for different ways of acquiring data.
This article presents the method of interpolation of topographical and geodesy information on
a section of water-course, basing on the data from maps or from the measurements in the terrain.
The software used for data processing as well as sections creating was the AutoCAD Civil 3D.
The achieved data were used to calculate return periods using the “rainfall formula” method.
