A Manual of Lake Morphometry

In this context morphology means the study of lake forms and form elements, their genesis (from geographical and geological viewpoints) and their role in a broad physical limnological perspective. Lake morphometry deals with the quantification and measurement of these forms and form elements.

This section is meant to give a general working guide on how to plan and perform hydrographic surveys for scientific purposes with echosounding equipment. The ultimate goal of the survey should be a bathymetric map with a specified level of information.

The base for the bathymetric map construction is the echogram. After the field-work is finished the echogram for each track is cut into a separate strip. The depth intervals that are to be used on the bathymetric map should then be determined (see section 4.1. and 4.2.). The general principle is that the contour-line intervals (1_c in meters) should be positive integers. The relationship between contour-line interval (1_c) and number of contour lines (n) is given by: where D_max = the maximum recorded depth (in meters). For most scientific purposes, e.g. when bathymetric maps for whole lakes are concerned, one can conclude that between 4–20 contour lines are required.

Bathymetric maps are the source of most morphometric data used in limnological, hydrological and sedimentological contexts. The reliability of the morphometric data will depend on the accuracy of the bathymetric map, which in turn will depend on the intensity and accuracy of the hydrographic survey.

I am greatly indebted to Nils Sjödin, SMHI, for valuable help and guidance concerning the sections on echosoundings and bathymetric map construction, and for providing the figures to these sections. I would also like to thank Anders and Ramona Källström for their constructive remarks and linguistic revising, Marianne Berglund for typing the manuscript and Kerstin Andersson for drawing the maps and the diagrams. The work has been sponsored by the National Swedish Environment Protection Board.

Background data on Lake Vänern and its drainage area.