Aims of the Mansikkaniemi method of river sinuosity analysis: a re-evaluation of concepts

Abstract

The paper is a reply to the criticism directed at Mansikkaniemi's river sinuosity analyses by Matti Seppälä (Fennia 161: 2, pp. 000‑000), and at the same time a re‑evaluation of a number of concepts associated with the topic. Seppälä appeals to certain special cases to justify his rejection of the commonly employed principle of calculating sinuosity in terms of the ratio between the length of the river and the linear distance between the source and the mouth. However, this method has proved to work well for over 95 % of the world's rivers, and appropriate methods are available in the remainder of cases. Seppälä also refers to this general principle erroneously as the 'Mansikkaniemi method'.

At the time when the real 'Mansikkaniemi method' was developed, in 1969, concepts regarding sinuosity varied widely among research workers, e.g. the illogical use of terms to denote either the nature of the sinuosity observed or its extent. The indices in use at that time were also poorly adabtable to the analysis of young river valleys in the area of crystalline bedrock, nor did they provide any indication of the distribution of sinuosity over the course of the river. For these reasons, the Mansikkaniemi method was conceived as a means of determining 'how the degree of sinuosity varies in different parts of a river and what kind are the loops of the river, small or great'. It is shown that the method does indeed serve to reveal these facts.

The crucial problem in sinuosity studies is that of determining the general course of the river valley, and consequently its length. The Man­sikkaniemi method enables the course of the valley to be determined un­ambiguously by reference to the distance between the source and the river mouth and to intervals defined in accordance with this. In this way subjective judgements on the course of the river are avoided. It is also demonstrated that the method is well suited to the construction of regional comparisons, despite Seppälä's claim to the contrary. In addition, new geo­morphological indices are proposed for denoting the properties of given areas of river valleys.