THE STREAM-LENGTH GRADIENT INDEX AND THE CORRESPONDING LANDFORM STRUCTURES OVER THE KIULU RIVER, NORTHWEST SABAH

Abstract

In this paper, we explored the relationship between the stream-length gradient index over the Kiulu River upstream and its respective landform. The knickpoints derived from stream-length gradient index detected sudden drop in elevation that may be associated with recent tectonic activity over NW Sabah. To illustrate the changes in the stream profile, two knickpoints, F1 which coincided with historical earthquakes, and F2 which showed peak anomaly are selected. The landform over knickpoint F1 showed river diversions whereas the landform over knickpoint F2 showed deep ponding. Both field sites, however showed consistent alternation between rapids and ponding forming a step-like landform where the inferred normal fault is oriented at N40E. The stretched landform over the Kiulu river sites supports an extension setting that may be associated with gravity-sliding tectonics over NW Sabah.

Keywords

• stream-length gradient index
• knickpoints
• extension tectonics.