In order to determine the most appropriate geometrical parameters of regulated watercourses, this paper presents some ways to identify the natural course thereof. In addition to analysing the types of curves approximating the test object, the authors have also described the methods of studying the range of these curves. In order to determine the degree of relationships between the variables of the studied watercourses, the authors have analysed the correlation coefficients. The paper presents the findings pertaining to the best-matched curves approximating the given object.