Landscape response to progressive tectonic and climatic forcing in NW Borneo: Implications for geological and geomorphic controls on flood hazard
|Author(s)||Menier David1, Mathew Manoj1, Pubellier Manuel2, Sapin Francois3, Delcaillau Bernard4, Siddiqui Numair5, Ramkumar Mu.6, Santosh M.7, 8|
|Affiliation(s)||1 : Univ Bretagne Sud, Lab Geosci Ocean, CNRS, UMR 6538, Rue Yves, F-56017 Mainguy, Vannes, France.
2 : Ecole Normale Super, CNRS, UMR 8538, 24 Rue Lhomond, F-75231 Paris 05, France.
3 : Total E&P MENA Dubai, H Dubai Off Tower,24th Floor,1,Sheikh Zayed Rd, Dubai, U Arab Emirates.
4 : Univ Caen, UMR M2C 6143, Morphodynam Continentale & Cotiere 24, F-14000 Caen, France.
5 : Univ Teknol PETRONAS, Fac Geosci & Petr Engn, Tronoh 31750, Perak, Malaysia.
6 : Periyar Univ, Dept Geol, Salem 636011, India.
7 : Univ Adelaide, Dept Earth Sci, Adelaide, SA 5005, Australia.
8 : China Univ Geosci, Beijing Sch Earth Sci & Resources, 29 Xueyuan Rd, Beijing 100083, Peoples R China.
|Source||Scientific Reports (2045-2322) (Nature Publishing Group), 2017-03 , Vol. 7 , P. 457 (18p.)|
|WOS© Times Cited||45|
Empirical models have simulated the consequences of uplift and orographic-precipitation on the evolution of orogens whereas the effects of these forcings on ridgelines and consequent topography of natural landscapes remain equivocal. Here we demonstrate the feedback of a terrestrial landscape in NW Borneo subject to uplift and precipitation gradient owing to orographic effect, and leading to less-predictable flooding and irreversible damages to life and property. Disequilibrium in a large catchment recording the lowest rainfall rates in Borneo, and adjacent drainage basins as determined through., a proxy for steady-state channel elevation, is shown to result in dynamic migration of water divide from the windward-side of the orogen towards the leeward-side to attain equilibrium. Loss of drainage area in the leeward-side reduces erosion rates with progressive shortening resulting in an unstable landscape with tectonic uplift, gravity faults and debris flows. C-14 dating of exhumed cut-and-fill terraces reveal a Mid-Pleistocene age, suggesting tectonic events in the trend of exhumation rates (> 7 mm a(-1)) estimated by thermochronology, and confirmed by morphotectonic and sedimentological analyses. Our study suggests that divide migration leads to lowered erosion rates, channel narrowing, and sediment accretion in intermontane basins on the leeward-side ultimately resulting in enhanced flooding.