This paper is based on Scandolara (1990), RADAMBRASIL Project (1978), Nascimento et al (1977), Christofoletti (1980), Soares and Fiori (1976) and Cunha (1995) and analyses the geomorphologic aspects of the Tapagem River, Rondonia.

The identification of the morphological compartments of the basin was based on cartographic material and photo-interpretation using 30 monocromatic aerial photographs (1964) at the approximate scale of 1:70,000 (CPRM-REPO). The information was controlled with fieldwork.

Geomorphological map of the Hidrographic Basin of Igarapé Tapagem, in the district of Candeias do Jamari (RO), between the latitudes 8°55'S and 9°21'S and longitudes 63°30' W and 63°40' W, in which the area is approximately 774,05 square kilometres. It is a system of sixth order, presenting three compartments with diversified characteristics in relation to the slope angle and drainage density. The main topics are identified as well as sources and types of valleys and other phenomena known regionally as "águas emendadas", "parana-mirins" and by field control, waterfalls, "terras caídas", lakes, "furos", island and fluvial lands, which ended up in the referred river. We conclude that the compartments I and III are more similar, while the II is peculiar because it is more fully accidental, needing special care in the planning of its occupation.