%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Ye, F. Y.
%A Barriot, J. P.
%A Carretier, Sébastien
%T Initiation and recession of the fluvial knickpoints of the Island of Tahiti (French Polynesia)
%D 2013
%L fdi:010060765
%G ENG
%J Geomorphology
%@ 0169-555X
%K Knickpoints ; Retreat rate ; Amphitheater-headed valleys ; Stream power law ; Tahiti
%K TAHITI
%M ISI:000315974400012
%P 162-173
%R 10.1016/j.geomorph.2012.12.031
%U https://www.documentation.ird.fr/hor/fdi:010060765
%> https://www.documentation.ird.fr/intranet/publi/2013/05/010060765.pdf
%V 186
%W Horizon (IRD)
%X In this paper, we study the origin and evolution of the 42 knickpoints spanning the Island of Tahiti, a large extinct shield volcano in the South Pacific Ocean (French Polynesia), by combining DEM analysis and numerical modeling. These knickpoints are located along rivers (107 in total) with a total length exceeding 6 km and with a total drainage of >3 km(2). The knickpoint locations do not correspond to lithology, tributary confluence, or uplift. We argue that these knickpoints have been initiated by a sudden sea level drop of 135 m 20 ky ago, and that the littoral cliffs circling two-thirds of Tahiti are the result of marine erosion that took place 7 ky ago from a stand level that was 5 m higher than now. The head-to-toe height of the knickpoints increases with respect to the knickpoints' distance from the ocean. The major process controlling the knickpoints is plunge-pool incision and the n = 2 stream-power model works well for modeling the profile form. The mean retreat rate of the knickpoints corresponds very well with a drainage-area dependant model with velocities ranging from 0.17 to 1.2 m/y.
%$ 064