Jean-Philippe Avouac photoJean-Philippe Avouac Professor of Geology:Director of the Tectonics Observatory:CaltechCaltech logo


Deciphering climate change impact in geomorphology

The evolution of a landscape results from the combination of tectonic and surface processes (erosion and sedimentation). Geormorphology is therefore a way to decipher past climate changes. In this respect, I am interested in developing  approaches to decipher the geomorphic record of climate changes based on simple physical models. Along those lines I have documented  and modeled shorelines in western Tibet . These shorelines indicate that the present arid conditions settled quite abruptly about 7000 years ago after an early Holocene climatic optimum  [Avouac et al., 1996]. In another study, we suggest that fluvial terraces in the Sub-Himalaya of Nepal, probably constitute some record of wet to dry climate change  [Lavé et Avouac, 2000].  Fluvial terraces might actually be used to quantify past hydrology. For example, the pattern and chronology of river entrenchment in the North Tian Shan piedmont was determined from abandoned river terraces and used to infer paleo-hydrological changes over the Holocene [Poisson and Avouac, 2004]. We deduce that in this very arid area of central Asia , the climate was much more humid, with about three times the present annual rainfall, during the early Holocene period. In the Dead Sea we have shown that alluviation is a very irregular process characterized by long periods of quiescience alternating with periods of fan build-up, reflecting the transient response of the drainage system to climate change [Klinger et al, 2004].

My contributions on the subject :

Avouac, J.P., L. Bourjot and J.F. Dobremez, Palaeoclimatic interpretation of a topographic profile across middle holocene regressive shorelines of Longmu Co (Western Tibet), Palaeo-3, 120, 93-104, 1996.

Klinger, Y., J.P. Avouac, D. Bourles, and N. Tisnerat, Alluvial deposition and lake-level fluctuations forced by Late Quaternary climate change: the Dead Sea case example, Sedimentary Geology, 162, 119-139, 2003. [PDF]

Lavé J., and J.P. Avouac, Active folding of fluvial terraces across the Siwalik Hills Himalaya of central Nepal,  J. Geophys. Res., 105, 5735-5770, 2000. [PDF].

Poisson B., and J.P. Avouac, Holocene hydrological changes inferred from alluvial stream entrenchment in North Tian Shan (Northwestern China), The Journal of Geology, 112, 231-249, 2004. [PDF]

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