CSDMS 2016 annual meeting poster ArvindSingh
Experimental investigation of the effect of climate change and tectonic anisotropy on landscape evolution
Alejandro Tejedor, University of Minnesota Minneapolis Minnesota, United States. alej.tejedor@gmail.com
Grimaud Jean-Louis, University of Minnesota Minneapolis Florida, United States. jeanlouis.grimaud@gmail.com
Efi Foufoula-Georgiou, University of Minnesota Minneapolis Minnesota, United States. efi@umn.edu
Abstract:
Based on a series of controlled laboratory experiments conducted at the St. Anthony Falls laboratory, University of Minnesota, we study the effect of changing external forcing such as the temporal pattern (i.e. increase/decrease) of precipitations as well as spatial distribution of uplift rates on landscape evolution at the short and long-time scales. These experiments were designed to create an evolving and self-organized complete drainage network by the growth and propagation of erosional instabilities (e.g. fluvial knickpoint retreat, hillslope erosion) in response to such external forcing. High resolution digital elevation (DEM) recorded every 5 min allowed following this evolution in both space and time. First, we focus on the investigation of how changes in the frequency and magnitude of large precipitation events affect the geomorphic and topologic re-organization of landscape across a range of scales. Our results show distinct signatures of extreme climatic fluctuations on the statistics and geometry of topographical features which are evident in widening and deepening of channels and valleys, change in drainage patterns within a basin and change in the probabilistic structure of “hot-spots” of change contributing to mass-wasting events, such as, landslides and debris flows. These results suggest a regime shift during the onset of the transient state in the transport processes on the fluvial regime of the landscape, i.e., from supply-limited to transport-limited. Finally, we investigate drainage reorganization in response to an asymmetric relative uplift rate with emphasis on the main drainage divide dynamics. This is achieved through the lowering of base levels at different rates on each side of the experiment. In response to such base level fall, the main drainage divide migrates towards the side of low base level fall rate. Such example provide experimental constraint on the evolution of a landscape under large-scale increase/decrease in drainage area on the sides of an orogen.
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