UNRAVELING SPATIAL AND TEMPORAL DRIVERS OF INCISION IN SOUTHERN TAIWAN: A STORY OF TECTONICS AND TYPHOONS
In addition to recent rapid uplift and related seismic activity, Taiwan has a wet tropical climate which causes rapid erosion rates speeding up the timescale of fluvial adjustment to tectonic forces. Monsoonal rains, tropical storms and infrequent, but large Typhoon events trigger large mass-wasting events that can cause significant aggradation in rivers slowing bedrock incision. In addition to spatial variations, this research will look for temporal changes in incision rates to investigate if past glacial-interglacial and finer climate changes influenced river incision rates due to changes in storm activity and related mass wasting events that would influence bed armoring.
We will use a combination of geomorphic mapping and luminescence dating of strath terraces to investigate temporal and spatial changes in incision rates. Twenty-eight samples have been collected from drainages spanning a 90 km N-S transect of southern Taiwan from the east and west side of the Central Range. Initial results indicate that strath terraces ranging from 4 - 350 m above the modern channel range in age from 1.2-150 ka and incision rates ranging from 0.3-2.5 mm/kyr. Spatial and temporal patterns in incision rates are just starting to emerge and will be presented.