River network is a typical spatial entity in the real world and its multi-scale transformation is a hot issue in the field of cartography and geographical information science. This paper proposes a multi-scale transformation approach for river network

which is based on morphing technology. This approach involves two cases. One is to make transformation between two corresponding rivers

and the other is for some rivers represented only on the larger-scale map. As for the first case

shape interpolation is utilized for morphing

where the intersections between rivers and the structures of rivers themselves are considered. For the second case

an indicator is defined by the total length of a river and its tributaries

and is employed to measure the importance of the river. By this indicator

some rivers of low importance

which are represented only on the larger-scale map

may be deleted in the process of multi-scale transformation. Through the case study

it is shown that the approach proposed in this paper can improve the results of morphing between rivers as well as the accuracy of river selection in the process of multi-scale transformation.