THE LENGTH OF COASTLINE OF THE ISLAND OF RAB

D. Tutic, M. Lapaine, N. Vucetic

Faculty of Geodesy, Chair of Geoinformation, Zagreb, Croatia

dtutic@geof.hr

The paper gives an overview of the measurements of the length of coastline of the Island of Rab in the Adriatic Sea from maps at scales 1:25 000, 1:50 000, 1:100 000, 1:200 000, 1:300 000, 1:500 000 and 1:1 000 000. All maps were or still are the official topographic maps produced by the same institution. Maps in smaller scale were derived by manual cartographic generalization from maps in larger scale. An elimination of deformations of map projections was performed. An estimation of the accuracy of measurements is given. The results of the approximation of the measured data by methods proposed by Volkov N. M. and Hakanson L. are given in order to predict the length of the coastline at larger and smaller map scales. Since new official datasets are available at larger map scales, predicted lengths by these two methods were compared with lengths obtained from real data. The predicted lengths were too short compared to lengths from real data and thus not satisfactory. A new approximation method by a logarithmic function is proposed which gives significantly better results. The results show that only moderate extrapolation of data is of use.