FATES-HYPERS 宿命 Sediment sinks at depositional terrace in upper reach of the Gaoping Canyon Cheng-Shing Chiang a,* and Ho-Shing Yu b* a Hsiuping Institute.

FATES-HYPERS 宿命FATES-HYPERS 宿命

Sediment sinks at depositional terrace in upper reach of the Gaoping Canyon

Cheng-Shing Chiang a, and Ho-Shing Yub

a Hsiuping Institute of Technology, Taichung, Taiwan, ROC

b Institute of Oceanography, National Taiwan University , Taipei, Taiwan, ROC


Introduction The capability of canyons:

Sediment transfer Erosion Deposition sediments are trapped in terraces temporary or perennial sediment traps types of terrace morphology terrace formation and evolution


Introduction

Sediments are traped within particular morphologies called terraces, with reference to fluvial environment. (Cirac et al.,2001; Gaudin et a.,2006)


What do we need to know about terrace?

morphology featuressinkprocesses

In terms of source to sink


Four types of terrace in Capbreton Canyon

(Gaudin et al., 2006)(Gaudin et al., 2006)

Horseshoe terraces (T1)• that is characterized by a flat, arcuate outer pattern surrounding an elongated and rounded

topographic high.

Hemispherical terraces (T2)• with a flat top and have an arcuate pattern

Rounded elongated terraces (T3)• that is located inside meander loops and with a rounded top

Flat elongated terraces (T4) that is flat and elongated parallel to the thalweg axis.


Evolution of Capbreton Canyon morphology

(Gaudin et al., 2006)(Gaudin et al., 2006)

T1 : Horseshoe terraces

T3 : Rounded elongated terraces

T4 : Flat elongated terraces


Types of terrace in the world


Cross-section morphology


Cross-section 340-1

terrace


Point bar terrace? Slide- or slump-related terraces ?

Seismic profile 340-1

terrace


Cross-section 340-4

Steep wall


Slide- or slump-related terraces


Depositional terraces occurred in meander bend


Horseshoe terracesT1


Chirp sonar profile C3

T1


Elongated terrace

T3

No cut-off presently


Compare with the Compare with the Capbreton canyonCapbreton canyon

arcuate pattern


ConclusionTerraces are well observed in the meandering segment of the canyon and mainly in inner parts of the meander bends, showing distinct depositional features of spill-over sediments to form levees.Four major types of terrace morphology have been established in the study area: Slide- or slump-related terraces, point bar terraces, horseshoe terraces (T1) and elongated terraces (T3).


We reveal the temporary sink of terrace of the Gaoping Canyon under the highstand of sea level as characterized by a direct sediment source from a small mountainous river with high sediment load.


Thanks, and your comments are welcomed

FATES-HYPERS 宿命 Sediment sinks at depositional terrace in upper reach of the Gaoping Canyon Cheng-Shing Chiang a,* and Ho-Shing Yu b* a Hsiuping Institute.

Documents

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