Geomorphic coupling and sediment connectivity in an alpine catchment - exploring sediment cascades using graph theory Tobias Heckmann a,∗ , Wolfgang Schwanghart b a Physical Geography, Catholic University of Eichstaett-Ingolstadt, Germany b Institute for Earth and Environmental Sciences, University of Potsdam, Germany Abstract Through their relevance for sediment budgets and the sensitivity of geomor- phic systems, geomorphic coupling and (sediment) connectivity represent important topics in geomorphology. Since the introduction of the systems perspective to physical geography by Chorley and Kennedy (1971), a catch- ment has been perceived as consisting of landscape elements (e.g. landforms, subcatchments) that are coupled by geomorphic processes through sediment transport. In this study, we present a novel application of mathematical graph theory to explore the network structure of coarse sediment pathways in a central alpine catchment. Numerical simulation models for rockfall, de- bris flows, and (hillslope and channel) fluvial processes are used to establish a spatially explicit graph model of sediment sources, pathways and sinks. The raster cells of a digital elevation model form the nodes of this graph, and simulated sediment trajectories represent the corresponding edges. Model results are validated by visual comparison with the field situation and aerial * Corresponding Author Email address: tobias.heckmann@ku.de (Tobias Heckmann) Preprint submitted to Geomorphology August 14, 2012